View source for Talk:Depth of field

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=== Hyperfocal in the "Same Picture" section ===
Assuming a lens with focal length and f-stop both modified by the same sensor format conversion ("crop factor"), I get the part where the equivalence breaks down as macro magnification becomes a big deal. But I don't understand the part about the equivalence breaking down at "as distance approaches the hyperfocal distance for the smaller format (the DOF of the smaller format approaches infinity)". As I calculate it, assuming also-scaled CoC, the hyperfocal distance should be the same for both formats. What am I missing? Thanks!
[[User:Mattdm|Matthew Miller]] ([[User talk:Mattdm|talk]]) 02:45, 25 March 2011 (UTC)

:What you're missing is that that comment is being applied to the condition stated as "With the same f-number."  Afterward, the f-number ratio that makes the DOFs equal is computed, and that works fine at distance, as you note.  But the DOF ratio itself doesn't work so well when one of the DOFs can approach infinity while the other doesn't.  There might be a better way to put all this to avoid the problem, so feel free to propose a rewrite (be bold, and we'll jump in and fix it we don't like it).  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 03:32, 25 March 2011 (UTC)

::Our DoF comparisons (like everyone else’s) make use of approximations at near and far distances; unlike most other sources, even Stroebel, we clearly describe what the simplifying approximations are at the beginning of the subsection. One is that the distance is much less than hyperfocal, so that as the hyperfocal distance is approached, the comparisons are no longer valid. We assume that focal length and CoC both scale with format; however, because the hyperfocal distance is given by

:::<math>H = \frac {f^2} {Nc} + f \,,</math>

::it is ''not'' the same for both formats, but rather scales approximately with format. I guess both Dick and I concede that the current wording may require a second read; however, at least we state what most other sources (except perhaps Bob Atkins) simply ignore. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 07:49, 25 March 2011 (UTC)

::Perhaps what’s not as obvious as it seems to me: the comparison becomes invalid when the magnification in ''either'' format approaches unity or when the distance approaches hyperfocal in ''either'' format. Because we assume magnification is proportional to format size, magnification approaches unity in the larger format first; because the hyperfocal distance is approximately proportional to format size, the distance approaches hyperfocal in the smaller format first. Perhaps we could state this, although to me, what we currently say in the article is more digestible than how I’ve just described it. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 22:30, 25 March 2011 (UTC)

== DOF - Increases vs Decreases ==

Two of my previous edits were reverted on the basis that they are incorrect, namely changing "increases" to "decreases" in the '''Effect on Lens Aperture''' section. The way the facts are presented contradict information elsewhere in the article.
::'''''Opening Paragraph''' (bold added by me for emphasis)''<br>"In some cases, it may be desirable to have the entire image sharp, and a '''large''' DOF is appropriate. In other cases, a '''small''' DOF may be more effective, emphasizing the subject while de-emphasizing the foreground and background."

::'''''Effect on Lens Aperture''' Section (bold added by me for emphasis)''<br>"Reducing the aperture diameter (increasing the f-number) '''increases''' the DOF; however, it also reduces the amount of light transmitted, and increases diffraction, placing a practical limit on the extent to which DOF can be '''increased''' by reducing the aperture diameter."
This contradicts the first paragraph.  From what I understand of DOF (and the first paragraph) is that put simply, a larger (deeper) DOF means more of the scene is in focus.  A smaller (shallower) DOF means only a specific range of objects will be in focus.  So by reducing the aperture diameter, it brings more things into focus which would mean it INCREASES the DOF. But the Effect on Lens Aperture paragraph states otherwise.  Please correct me if I am misunderstanding DOF or am missing something here with aperture sizes. 

Also, I was told my edits were unsourced.  I did not state any specific facts or impart any new information to the article, I was merely making it consistent.  How would one suggest I have sourced that better?
[[User:Hergio|Hergio]] ([[User talk:Hergio|talk]]) 18:19, 28 December 2010 (UTC)

:I don't see any such article edit under your contribs.  Can you link the diff and quote what you changed it to.  The text you bolded above seems to be correct and consistent with what you're saying when you state "reducing the aperture diameter, it brings more things into focus which would mean it INCREASES the DOF", so it's not clear what you would have changed.  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 19:28, 28 December 2010 (UTC)

::Edits were apparently made without logging in (using IP address 69.205.119.161). [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 02:23, 29 December 2010 (UTC)

:There is no contradiction between the two paragraphs quoted above. The first mentions situations for which large or small DoF may be appropriate but does not discuss how to control DoF; the second describes the effect of aperture on DoF without discussing whether large or small DoF is appropriate. The edits contradicted the well-established inverse relationship between aperture diameter and DoF, were challenged as incorrect, and thus required support from a reliable source. But the main objection was that the change was incorrect, which is why I (and I presume Kleopatra as well) reverted immediately, and asked for an explanation before making the edits again. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 02:23, 29 December 2010 (UTC)

== Hyperfocal distance depth of field using EasyTimeline ==

The chart is an interesting illustration, but it has several issues:
* There seems to be a confusion of aperture and numerical aperture; as [[Numerical aperture]] clearly indicates, at infinity,
::<math>N \approx \frac {1} {2\mathrm{NA}} \,,</math>
:and even then, the small-angle approximation breaks down for short-focus lenses.
* The symbol ''N'' is used to indicate aperture (''f''/''N''), whereas in this article and similar treatments, it’s used to indicate the denominator of that fraction (e.g., {{nowrap|“''N''<sub>1</sub>: ''f''/8”}} should be {{nowrap|“''N''<sub>1</sub>: 8”}}).
* I doubt that it’s obvious to most readers that the near limit of DoF for infinity focus is {{nowrap|''H'' − ''f''}} (I had to think for a minute), though perhaps this simply suggests that we should mention it in this article.
* The WLs to [[Exposure (photography)]] and [[Distance]] seem a bit off the wall for this context.
* The chart seems to imply the definition of hyperfocal distance used in this article, e.g.,
::<math>H = \frac {f^2} {NC} + f \,,</math>
:yet illustrates [[Hyperfocal distance#Mathematical phenomenon]] using the same symbol ''H''. The phenomenon holds only for the approximate hyperfocal distance
::<math>H \approx \frac {f^2} {NC}\,.</math>
* Because a larger version of the chart is not available, the text is quite small and hard to read, especially with the bunching up of the text of the headers in the stub columns (e.g., the first would be much easier to read if it were {{nowrap|“''f''<sub>1</sub>: 50 mm, ''N''<sub>1</sub>: ''f''/8”}} rather than {{nowrap|“''f''<sub>1</sub>:50mm ''N''<sub>1</sub>:''f''/8”}}). Slightly larger text would also help, but I recognize that this could make the chart unacceptably wide.
* A minor issue: quantity symbols ''H'', ''f'', and ''N'' should be in italics, as I’ve shown them.
I also wonder if the chart is as appropriate here as it is in [[Hyperfocal distance]]. The bulk of the illustration is the effect of successive values of ''H''/''x''; though it’s interesting, it usually isn’t useful in practical photography.

Some of the comments are largely personal preference, but at the very least, the outright errors should be corrected if this chart is to remain here or in [[Hyperfocal distance]]. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 00:34, 2 June 2011 (UTC)

I’ve addressed most of the easy-to-fix issues. The WLs to [[Exposure (photography)]] and [[Distance]] remain. I think the first should be changed to [[Aperture]] or perhaps removed. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 07:44, 25 June 2011 (UTC)

== Number, type, and quality of images ==

We’ve occasionally discussed a possible excess of images, especially ones illustrating shallow DOF. We’ve also done some housecleaning from time to time, though it’s been a pretty haphazard process. This article is now protected as a result of a silly edit war (or at least the beginning of one) over replacing one image of a cat with another. I don’t think we really need two images of a cat, and it’s not obvious that the proposed replacement is superior to the existing image.

I hope we never imply that a new image cannot be added, or that an existing image cannot be replaced with one that better illustrates a point. But we need a process for managing the image collection–a process that has at least some reasonable basis. Though it might be reasonable for an editor to propose an addition, and especially a replacement, before making the change, this approach will probably be very much the exception rather than the rule, and we have no basis for demanding it. But edit warring isn’t the solution, either, and I would think after a couple of reverts to a change or addition, it would be reasonable for the editor to discuss the issue here.

For any discussion to be productive, we need to have some criteria for what we want in images. Though I feel as if I’m stating the obvious, it seems to me that
* Any image should serve to illustrate a point in this article, and we should probably have no more images than necessary to illustrate any given point—[[WP:NOTREPOSITORY|Wikipedia is not an image repository]]. In some cases, we may have more images of one type than are needed, but we may also be missing images that would improve the article by illustrating a concept that may not be completely clear from the text alone.
* The better an image illustrates a point, the more it should be a candidate to replace an existing image or supplement what we have.
* All else being equal, of course, a good image should be preferable to an inferior one. But I would think there should normally be a certain threshold of improvement to justify replacement of an existing image. We have several very high quality images, including that of the Nikkor lens and the Tachinid fly; I think we also have a few that are less good.

We should also have a process for objecting to an addition or replacement with which we disagree. One approach is to mention the objective here before doing anything else, but that seems overly restrictive. I would think that, at the very least, a revert would offer a brief reason why the change or replacement was not thought helpful, with a request to discuss the proposed change here. In some cases, making comment here as well as in the edit summary may be a good idea. But as obvious as this may seem, the comments in the recent mini-war weren’t very descriptive.

Perhaps it would help if we created a simple road map of images that we think we should have, and compare that with what we do have, to arrive at additional images we want, current images for which we might want a better replacement, and perhaps some current images that really don’t further this article’s purpose. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 08:38, 25 June 2011 (UTC)


I am not sure how clued up you are with photography, but the one of the boy is an awful photo, as stated previously (I will do the same here) it is poorly lit, of poor quality, and has no points of reference, something which the cat picture does, it is also the only picture to do so. Personally, I find the other picture hurts my eyes, it is far too harsh. I am also cheesed off I was followed by the Gang of 4, who undid a load of my edits. 
[[User:Jamesington|Jamesington]] ([[User talk:Jamesington|talk]]) 10:33, 25 June 2011 (UTC)jamesington

:If you look at my previous edits here, I think you’ll see that I understand photography, and DOF in particular, quite well. I agree that the photo of the boy is unlikely to win Photo of the Year. But it does illustrate one point quite well—that out-of-focus highlights have the shape of the lens aperture stop, and that alone may justify its inclusion until we find a better image to illustrate this point. The caption should probably be updated to reflect what I just said.
:I assume that by “cat picture”, you mean the one you added; it’s less clear what you mean by “other picture” (the current cat picture?). In any event, I’m not sure that a “point of reference” is essential, and that a picture “hurts your eyes” is hardly justification for replacing it.
:A confrontational approach (e.g., references to the “Gang of 4”) usually isn’t the most effective one. I agree with Ron Ritzman’s comment at [[AN/I]]: after a couple of reverts, you should have gone to the Talk pages, and those who reverted you should have provided better and less-confrontational edit summaries. I can’t exactly cast the first stone, because I’ve occasionally been a bit short with people in edit summaries, and I restored one of your edits that I would have supported reverting had I paid closer attention to the history. So to some extent, we’re all guilty as charged.
:Getting back to the task at hand: as I’ve indicated, I prefer the existing cat image to yours (and would keep the image of the boy for other reasons, at least for now). But if replacement finds consensus, that is how it should be.
:I suggested developing a list of desired image types so that deciding which images to add, keep, or replace might seem a bit less capricious. It might also eventually lead to making this article better.
:Incidentally, there’s no need to add your name in signing a post—the four tildes include it automatically. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 23:47, 25 June 2011 (UTC)

No one has made any suggestions, so I offer a few.

'''Current images'''
* Move the image of the camera and butterfly back to the lead where it started out, because it’s most effective as an simple, informal illustration of the concept.
* Move the image of the boy to the section ''Acceptable sharpness'', and change the caption on to mention the out-of-focus highlights in the shape of the aperture.  If a better image showing this can be found, replace this image.
* Consider removing the two digitally processed images from the lead. It’s not clear how they relate to this article; consequently, they seem gratuitous, especially the second one.
* Consider replacing the four images in the section ''Effect of lens aperture'' with ones in which the effect is more obvious at the size displayed.  Two images might suffice, and would better match the figure at the right; the images of the jonquil flower would fill the bill quite well, they also well illustrate isolation of the background, and I'm not sure we want to include them twice.  Going to two images rather than four might oversimplify, but the effects of aperture would be more readily apparent.
* Revise the caption for the image of the circuit board to note the softening in the plane of focus at ''f''/32.

'''New image'''
<ul>
<li>Four images of a scene from the same camera position but with different focus settings:
<p style="margin-left: 1em; margin-top: 0; margin-bottom: 0">–&ensp;One at the nearest object to be sharp, with a large aperture
<p style="margin-left: 1em; margin-top: 0; margin-bottom: 0">–&ensp;One at the farthest object to be sharp, with the same aperture
<p style="margin-left: 1em; margin-top: 0; margin-bottom: 0">–&ensp;One at the harmonic mean, with the same aperture
<p style="margin-left: 1em; margin-top: 0; margin-bottom: 0">–&ensp;One at the harmonic mean, with an aperture that has the DOF extend from the near object to the far object
<p>
I’m not sure where this would go (perhaps the lead), and some additional text might be needed to explain it. The purpose would be to illustrate what’s going on for a reader unfamiliar with photography. We’re currently loaded for bear on some of the more complex aspects, but may fall a bit short on the simpler ones (as do many other treatments). The current macro image could serve as a contrast showing a small DOF.
</li>
<li>Images to possibly replace the four in the section ''Effect of lens aperture'', discussed above.</li>
<li>Better quality image to replace the one of the boy but still show the aperture shape in the OOF highlights.</li>
</ul>
[[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 02:42, 28 June 2011 (UTC)

[[File:Olhos de um gato-3.jpg|right|thumb|And here's a better cat image.]]
[[Image:Kittyplya03042006.JPG|right|thumb|At {{f/}}2.8, the cat is isolated from the background.]]
:Jeff, I think those are all great suggestions, but I'd like to keep one CG image, like Glass ochem dof2.png, to show that the effect of DOF can be simulated by ray tracing.  And I found a better cat image from the [[Cat]] article. It works both at thumbnail size and zoomed in. [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 14:37, 28 June 2011 (UTC)
::All but the new images (arguably the most important, unfortunately) are easily done, subject to having things lay out reasonably. Unless someone objects, I’ll give it a shot.
::I see the two cat images as about equal, though I don’t have strong feelings about them. I’ve put the other one here for easy comparison. Given the recent fracas, I think we should give others a chance to weigh in. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 19:19, 28 June 2011 (UTC)

::Easy part done—see how it looks. I’ve left the cat image alone for now. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 22:12, 28 June 2011 (UTC)

:::I think [[:File:Kittyplya03042006.JPG]] is the better cat picture because it has an out-of-focus foreground (the paw) illustrating DOF better. '''[[User:cmglee|cm&#610;&#671;ee]]&#9786;[[User_Talk:cmglee|&#964;a&#671;&#954;]]'''  17:27, 29 June 2011 (UTC)
::::I had the same reaction, though as I’ve said, I don’t have strong feelings about the choice. If we decide to keep this image, perhaps we should revise the caption accordingly (we already describe isolation from the background in the images of the jonquil flower). [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 00:53, 30 June 2011 (UTC)
::::Yes, that one's OK, too.  We could mention that the paw is closer than the near edge of the DOF and the body is farther than the far edge.  And that the DOF depends on how big you make the picture.  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 03:59, 30 June 2011 (UTC)

== cat == 
[[File:Depth of field Cat.jpg|thumb|Jamie's shoe cat]]
[[File:Shallow Depth of Field with Bokeh.jpg|thumb|Boy with hedge]]
If you have seen my name before you know why I am here... The picture of the boy I have replaced with a cat, as it has been edited in photoshop. as it is chopped I dont think it should be highlighting depth of field when it could be an entirley fake image and some guy is just puhing his kid, just like people claim I am doing with the cat. Wikipedia is something anyone can edit right? So then instead of reverting my edits and suggesting similar pics of what I have already added why not just let me edit for gods sake.  <small><span class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Jamesington|Jamesington]] ([[User talk:Jamesington|talk]] • [[Special:Contributions/Jamesington|contribs]]) 23:14, 28 July 2011 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

:Could be, but so what?  Is there any reason to dislike or suspect the image of the boy?  I think it's good; and I don't see anyone pushing it who is relating to it, do you?  Chokity, who took it, placed it about a year ago, and nobody objected to it, so no pushing was needed to get it to stay.  What image hasn't been adjusted in Photoshop or some such?  A reason to not just let you edit is that you seem to have a [[WP:COI]] in really wanting your own cat's photo to appear in various articles, when other editors think it's not the best choice.  Why not just contribute where no such appearance of COI is possible?  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 01:25, 29 July 2011 (UTC)

:Be assured that Dick and I have nothing against your cat (or perhaps just your cat picture)—as we seem to have agreed above, the primary objective of images here is to illustrate what we discuss in the article—it’s not an image gallery. The photo of the boy well illustrates a concept in the article—that blur spots have roughly the shape of the aperture stop. This information has now been lost for the moment as a result of the games here. [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 08:52, 29 July 2011 (UTC)

:My point is it is a horrible image. The background is harshly blotted. And the face is in a harsh light. It is not a nice picture. also shows some ambiguous hedges, as opposed to the cats obvious shoe.  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/90.206.178.99|90.206.178.99]] ([[User talk:90.206.178.99|talk]]) 22:51, 29 July 2011 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

::Your point is taken.  But your judgement is biased.  If someone is to decide that your photo is better, that someone shouldn't be you.  I think the image of the boy is good, and effective. [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 23:01, 29 July 2011 (UTC)

:::I can't believe we are still debating which picture(s) to include. Trying to be as neutral as possible, the boy image illustrates bokeh better while the cat image has better light. But why a shoe?

:::Why don't we instead list the phenomena we want to illustrate (e.g. bokeh and out-of-focus foreground *and* background), then someone go out and take a photo fitting the criteria, instead of picking some random photo satisfying just some of them. (Also preferably use a neutral subject to avoid allegations of pushing one's cat or kid!) '''[[User:cmglee|cm&#610;&#671;ee]]&#9786;[[User_Talk:cmglee|&#964;a&#671;&#954;]]'''  01:12, 30 July 2011 (UTC)
::::The boy picture is used for one thing; its caption reads "Out-of-focus highlights have the shape of the lens aperture."  It's possible someone could find or make a better image for this concept, but this one is OK.  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 01:20, 30 July 2011 (UTC)

::::I actually have listed, in great detail, what might be good to see in images, and this seemed to find general agreement. If there are other ideas, by all means mention them. I don’t think the image of the boy is great, and honestly questioned its addition. But it well illustrates one of the  points on which we seemed to agree, and I finally changed the caption to reflect the value that the image provides here. I don’t think Jamesington’s image is all that good, either—the cat’s face seems pretty dark to me (and the white patch on the cat’s throat distracts. The composition isn’t all that good, either—with the shoe at the left and the cat almost centered, the balance is off. So I think the current cat picture is better; if it were a tie, it would prevail anyway in the interest of article stability. And the picture of the boy is preferable to Jamesington’s cat picture for reasons already stated.
::::I suppose a “neutral” image couldn’t hurt, but if we were to insist on it, if might be tough to find many candidates. Because the problem here seems to be with one editor, I’m not sure we need to be too concerned. All other things being equal avoiding pictures of family members or pets is probably preferable—but I don’t think it should dictate.
::::Finally, Jamesington—would you please sign your posts with four tildes? [[User:JeffConrad|JeffConrad]] ([[User talk:JeffConrad|talk]]) 06:13, 30 July 2011 (UTC)

== Near:far -- telecentric case? ==

At the risk of adding complexity to a long and nuanced article, this line caught my attention: "The DOF beyond the subject is always greater than the DOF in front of the subject." While that is certainly usually true, isn't it not the case for an object-[[telecentric]] system? My sense is that the typical near:far asymmetry is due to the combination of both NA and magnification decreasing with distance. For a telecentric system, I'm thinking: (1) the [[entrance pupil]] is at infinity so the angle subtended by the EP doesn't depend on distance, and (2) the magnification is uniform with distance. 

On graph paper, this looks right. I have a nominal point at ''x''=&minus;2, a paraxial converging lens at ''x''=0, a 2-unit-diameter stop at ''x''=2, and an image plane at ''x''=4. 
* If I put another point at ''x''=&minus;1, its marginal rays are parallel to those of the first point (by the fact that the EP is at infinity), so the marginal rays go up to ''y''=1 and then are columnated, making an image spot with diameter 2.
* If I put a third point at ''x''=&minus;3, its marginal rays are again parallel, hitting the lens at ''y''=3, kissing the stop at (2,1), coming into focus at ''x''=3, and hitting the image plane at ''y''=&minus;1, again making a spot with diameter 2.
If that's correct, then the near:far distinction breaks down for a telecentric lens, No? [[User:BenFrantzDale|—Ben FrantzDale]] ([[User talk:BenFrantzDale|talk]]) 14:36, 11 August 2011 (UTC)

== Depths of field plot ==

The plot is confusing (well, to me, anyway) and needs at least a clearer explanation, and part of the caption reads "the depth of field is increased by using a shorter focal length or smaller aperture." Shouldn't it be *longer* focal length or smaller aperture? [[User:Sergivs-en|Sergivs-en]] ([[User talk:Sergivs-en|talk]]) 09:02, 14 December 2011 (UTC)


== Same focal length for both formats ==
in this section you can find following statement (take a closer look regarding info about perspective):

... the DOF ratio is the same as that given above, but the images differ because of the different perspectives and angles of view....

a few lines below one can find something different regarding the very same perspective:


... so the DOF ratio is in direct proportion to the format size. The perspective is the same for both formats, but because of the different angles of view, the pictures are not the same.


in my opinion this is of course mistake. the perspective IS THE SAME. angles of view are different because of sensor sizes, but perspective is absolutely the same. we SEE different portion of the picture but from the same perspective. 

my explanation: imagine two cameras sharing the same perspective (like in 3D stereoscopic rig) with 50% transparent mirror. ignore inverting the picture, color balance and image flipping which is caused by mirror.  both cameras are matched to each other, so both cameras are seeing the same picture. ZERO PARALAX, SAME OPTICAL AXIS. SAME PERSPECTIVE, SAME LENS, SAME FOCAL LENGHT, SAME F STOP, SAME SENSOR SIZE. and obviously - everything is the same. ok. 

NOW - we are CHANGING one of the two cameras. this new camera has SMALLER sensor size. everythig else is as before: ZERO PARALAX, SAME OPTICAL AXIS. SAME PERSPECTIVE, SAME LENS, SAME FOCAL LENGHT, SAME F STOP.
what is different now? perspective? no. just the portion of the image sensor is seeing!  perspective for sure is the same, because we didn't change that.

when trying to explaing this in a different way  i am often using a POSTCARD as an explanation. if we see certain landscape with the, say house in the midle of this postcard  (this is our camera with bigger sensor size) we cannot change PERSPECTIVE by cutting out outer part of this very postcard, so only house in the middle is now visible (smaller sensor camera). we will see just different INFORMATION on this postcard but from the very same perspective.

that's it.

thank you,

[[User:Filip kovcin|Filip kovcin]] ([[User talk:Filip kovcin|talk]]) 22:19, 29 December 2011 (UTC) filip kovcin,  warsaw, poland

:It's contrasting two different ways of comparing same focal length.  One case has same subject distance and hence same perspective; the other different distance and perspective, but same field width at the subject distance.  Maybe you can fix it to make the cases more clear.  The current wording "Another approach..." perhaps doesn't make it clear enough that it's introducing a different situation.  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 00:00, 30 December 2011 (UTC)

== [[:File:Glass ochem dof2.png]] to appear as POTD soon ==
Hello! This is a note to let the editors of this article know that [[:File:Glass ochem dof2.png]] will be appearing as [[Wikipedia:picture of the day|picture of the day]] on July 22, 2012. You can view and edit the POTD blurb at [[Template:POTD/2012-07-22]]. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the [[Main Page]] so Wikipedia doesn't look bad. :) Thanks! <span style="font-family:Verdana; ">—'''[[User:Howcheng|<span style="color:#33C;">howcheng</span>]]'''  <small>{[[User talk:Howcheng|chat]]}</small></span> 23:02, 21 July 2012 (UTC) <!-- substituted from [[Template:UpcomingPOTD]] -->
{{POTD/2012-07-22}}

== The formulas for D_F and D_N are wrong.  ==

The final step, using the found equations for V_N and V_F in the thin lens formula gives a different result than shown in the wiki page. Solved by hand and using wolfram alpha give this result:

http://www.wolframalpha.com/input/?i=1%2Fx+%3D+%281%2Ff%29+%2B+%281%2F%28%28f*v%29%2F%28f%2BN*c%29%29%29+solve+for+x

idk how wikipedia editing/math works but someone who does should fix this

[[Special:Contributions/80.246.200.217|80.246.200.217]] ([[User talk:80.246.200.217|talk]]) 14:35, 27 November 2015 (UTC)

:Wolframalpha uses  Mathematica.   I  use equally powerful  Maple  to solve the six equations as a set,  and obtain result easily,  see rearranged section 11, and the Maple code in the Maple link. --[[User:Gisling|Gisling]] ([[User talk:Gisling|talk]]) 07:10, 20 February 2016 (UTC).

::And one would not normally express it as IP did, with lens-to-film distance as an independent variable.  It's not clear what he thinks is wrong, but his version is certainly odd.  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 07:40, 20 February 2016 (UTC)

== Changing Away from 'lens can only focus on one point' concept in Circle of Confusion ==

As mentioned in the change summary, a lens focuses on a plane rather than a point. It's important for an understanding of DOF to recognize that the DOF is with respect to the plane of focus rather than the sensor (film is a sensor) plane; although for the special case of a system with limited adjustments where the lens axis is always perpindicular to the sensor plane, the DOF distances can easily be converted to be with respect to the sensor plane.  This conversion has been done for decades by camera and lens makers to achieve convenient and practical use of cameras that don't have lens swing or tilt capability.  That this is common practice may lead many of us to stop thinking generally and tend to think in terms of these limited-capability imaging systems that have been in widespread use for over 50 years. Editors please beware of this trap.
[[Special:Contributions/4.7.25.146|4.7.25.146]] ([[User talk:4.7.25.146|talk]]) 21:00, 4 April 2018 (UTC)

Removed misleading synonyms for DOF. With my limited resources, I couldn't find a reliable reference that equates "focus range" or "effective focus range" with DOF. It wouldn't be a big surprise if it is contained somewhere in the context of limited adjustment cameras; or in operator's instructions written with marketing or public relations in mind;  however, it would add to the misconception that DOF may generally be obtained by simply measuring from the imaging system to objects imaged with acceptable clarity, and subtracting the nearest from the farthest. This will only work when the lens axis is perpendicular to the sensor plane of a flat sensor.
[[Special:Contributions/4.7.25.146|4.7.25.146]] ([[User talk:4.7.25.146|talk]]) 19:16, 7 April 2018 (UTC)

== Article is massive ==

Right now, the article is extremely long! Over two-thirds of the article is taken up by the sections "DOF Formulae" and "Derivation of the DOF Formulae". These seems unnecessary and possibly be split into their own articles or removed outright. Not even the physics or mathematics articles have such lengthy derivation sections. [[User:MarkH21|MarkH21]] ([[User talk:MarkH21|talk]]) 10:41, 8 January 2019 (UTC)

:Removed the formulae sections because Wikipedia is not a textbook ([[WP:NOTTEXTBOOK]]). [[User:MarkH21|MarkH21]] ([[User talk:MarkH21|talk]]) 06:15, 14 January 2019 (UTC)

::I agree it's massive and bloated, but it would probably be better to cut it by about half than to throw out all that work of many editors over many years.  If you think a split to another article on DOF math is a solution, let's consider that, too.  But just chucking it all out seems like not the best solution. [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 06:23, 14 January 2019 (UTC)

:::A massive trimming or split of the formula section are possible solutions that I would probably be fine with. With regards to the derivations, I believe that it should be entirely removed. Its inclusion does not really make sense, Wikipedia is [[WP:NOTTEXTBOOK|not a textbook]] nor is it a place to give the mathematical derivation of known scientific & engineering phenomena. Anyone who wants to learn about how to derive the formulae would just refer to the referenced textbooks / sources, as one would do for any other subject with mathematical formulae.

::: Just to note, whether editors have spent significant time writing material should ''not'' be a consideration for whether written material should be kept. That's not to say that the work isn't appreciated or potentially valuable though! [[User:MarkH21|MarkH21]] ([[User talk:MarkH21|talk]]) 08:15, 14 January 2019 (UTC)

::::Following [[WP:NOTTEXTBOOK]] / [[WP:NOTHOWTO]], I have trimmed the "DOF Formulae" section down while retaining most of the formulae, but I'm still not convinced that the section belongs. The derivations section is gone because that really does not belong.

::::There are still some overly-detailed sections and material more fitting of a textbook/how-to, so I am adding the "how-to" tag. [[User:MarkH21|MarkH21]] ([[User talk:MarkH21|talk]]) 13:57, 20 January 2019 (UTC)
:The derivations aside -there's quite a lot of repeated content in the article and it's at quite a high level. I think there is a fair amount of rewriting that could be done and I'm happy to make a start on that if people are happy to look over my shoulder a bit? [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 17:26, 24 January 2019 (UTC)
::I took an initial swing. Will come back with more books shortly[[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 19:37, 24 January 2019 (UTC)
:::So far, the revisions look quite good and are much appreciated! Thanks! [[User:MarkH21|MarkH21]] ([[User talk:MarkH21|talk]]) 04:43, 29 January 2019 (UTC)
::::Thank you - it makes it much easier to keep going when there's a vote of confidence. :) [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 09:54, 29 January 2019 (UTC)
Maybe we should make an article [[Depth of field formulae and derivations]] or [[Depth of field calculations]] or something like that to preserve the bulk of the removed material? [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 05:18, 29 January 2019 (UTC)
:::::I think that's a sensible suggestion and I'd be for it.  My personal preference is to leave the formulas (and derivations) until the structure of the rest of the article has played itself out (because some formulas might end up inline, and I feel like some aren't relevent to DoF anyway...) but I'm without strong opinion on it. [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 09:54, 29 January 2019 (UTC)
:::::: I've now looked over the derivations that were removed properly.  I think we should have formula (because it provides the exactness that we can't deliver with a general introduction text), and I think that the derivations help with that; however I don't think these are particularly clear derivations even to someone with a fairly solid maths background - I think that we'd do much better with geometric deviations some text and a bunch of diagrams. I'm still on the fence, but I'm now at "I think we should probably have derivations, but I don't think those derivations are half as good as you'd find on YouTube" [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 10:13, 29 January 2019 (UTC)
:::::Please, let's place the redacted derivations into the suggested [[Depth of field formulae and derivations]] or [[Depth of field calculations]] article (or the like). There are plenty of links at photography forums such as photo.net, dpreview.com, photography.stackexchange.com, etc., that have linked to this article for years, and now (apparently) suddenly, the information is gone. [[User:Sbb|sbb]] ([[User talk:Sbb|talk]]) 01:30, 24 March 2019 (UTC) '''Edit'': While the information might better belong at Wikibooks, the simple fact is that so much of Wikibooks' content is just poor. It has no life, community, or upkeep, from most of my readings there. So what was well-written, and pretty well diagrammed, is now just lost to the ether.

== Todo list ==

Some bits I'd like to do in the future - I thought I'd put them here so a) I don't forgot and b) people have a chance to object. 

* I'd like to improve the explanation of what depth of field and circle of confusion actually *are* so it's obvious to the non-technical reader
* I'd like to add in some diagrams  (hopefully animated) and proper text for how the depth of field changes with focal length, subject distance, and aperture.
* I'd like there to be a decent section on [[Bokeh]], there should be some nice illustrations of things like fancy heart shaped Bokeh ([https://www.flickr.com/photos/igoussev/3958709848/in/photolist-72Pqw5-aodDXr-qD4jYf-8XXP8v-5993t7-Vj54aS-72Pmaf-72Pm1S-cX1C5u-CDZEyo-cX1BKC-qAZugS-BUP33q-MC1pz2-MC1Qen-MHRxKp-rNitgw-4bqGi6-5EoCsE-FAzSiR-72Ksx8-72KkXM-6xLGH5-72KoZB-9iwSNw-JnWyyj-72Kubn-72Ktpp-FzyFyh-7vmopu-a4J91h-eUNyQx-72Psih-eipbaA-72Kth6-VDqt9s-boLvxX-TTcy7d-cgm4mA-aS42vt-8ZMsu9-stAyD-5JLW9Q-73yir3-9TimVZ-jMiHyM-anFDsp-9bpSSi-dre3yK-7syXcF] has the right licence) 
* I'd like to have some notes on the extremes of depth of field (lots of examples in [https://drive.google.com/file/d/0B6w2XfPHEcZYVTZ5YzFzdXc3b0U/view] 
* From the above - would be nice to add in some content on [[Group_f/64]] for a bit of colour
* The 'object field methods' section needs work - Merklinger's work appears to be self-published (interesting to read thought tho - [http://c-langkjaer.dk/prog/TIAOOFe.pdf] and cited a few times in Google Scholar (but hardly mentioned in Google Books) - and it's been presented as the main opinion with [[Ansel_Adams]] being relegated to the 'other people think' section. :s [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 09:57, 29 January 2019 (UTC)
:The examples of extreme depth of field weren't actually that good, but group 64 should be excellent. I've also added the heart shaped bokeh.  I've done some more rewriting today, but I'm also noticing that a lot of the content isn't about depth of field and really belongs in [[aperture]] or one of the other photography/optics articles.[[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 21:37, 27 January 2019 (UTC)

I'd keep the [[Bokeh]] stuff in its own article.  I like Merklinger's work, and it's respectable enough, being cited, though self-published.  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 18:13, 29 January 2019 (UTC)
: For sure, I mistakenly wrote bokeh above when I meant 'illustrate that points turn into the shape of the aperture by way of the cool heart shaped ones' - I do think that we should link up a little better with Bokeh as well. [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 16:09, 30 January 2019 (UTC)

== Object Field section ==

I'm looking at [[Depth_of_field#Object_field_methods]] and having read the main source I've got a few issues....

# The key part of the Object field method Merklinger proposed seems to be about making it easy to calculate depth of field - but that's not in the section
#  The section draws a false contrast. Adam's appears to be saying: "Photos look better when close things are as sharp or sharper than far things" (I don't have that source, but I understand that matches up with his body of work), whereas Merklinger is saying "if you want to read text on a boat that's far away, then you have to make sure it's very sharp - you don't have to work as hard if it's close." - I don't think those two views are particularly in conflict and I feel like they should be presented as such. 
# It feels like it's in the wrong bit of the article - at this point the reader doens't know what influences DoP, or even that the focus point isn't in the middle - I feel like those bits go first. 

I'm unsure how to rewrite (or restructure) to get this right - does anyone have any ideas (or the Adam's source)? [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 19:20, 30 January 2019 (UTC)

:I think the object field method is sensible as a scheme in which both Adams's and Merklinger's contradictory opinions can be illustrated and contrasted.  It's also used in a neutral way by von Rohr, as described in the Thomas Dallmeyer 1899 book (and see my [http://www.dicklyon.com/tech/Photography/DepthOfField-Lyon.pdf unpublished survey about this stuff]).  There's more in [https://books.google.com/books?id=AJRBAQAAMAAJ&pg=PA98#v=onepage&q&f=false Dallmeyer's book] than I realized at the time (before I had Google Book Search to help me).  You can't count on my unpublished synthesis, but you might find it a useful guide to the history and approaches. [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 18:14, 31 January 2019 (UTC)

:The closest thing I see in the cited Adams 1980 book is [https://books.google.com/books?id=4ZZDDwAAQBAJ&pg=PA115&dq=%22advise+caution%22+%22using+depth+of+field%22&hl=en&sa=X&ved=0ahUKEwiW0KrH05jgAhVTLX0KHYmjCvgQ6AEIKjAA#v=onepage&q=%22advise%20caution%22%20%22using%20depth%20of%20field%22&f=false this bit].  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 18:31, 31 January 2019 (UTC)
:No, it's on page 51 more explicitly: [https://books.google.com/books?id=4ZZDDwAAQBAJ&pg=PA51&dq=%22near+objects+should+be+given+preference%22&hl=en&sa=X&ved=0ahUKEwj2vcD21ZjgAhUkCTQIHciwBxsQ6AEIKjAA#v=onepage&q=%22near%20objects%20should%20be%20given%20preference%22&f=false], as our ref 5 says. [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 18:42, 31 January 2019 (UTC)
::Thank you muchly on all counts! The sources and the review a both going to be brilliant - I'm semi-learning this as I edit (I *thought* I knew about it) and it's great to have someone with real expertise looking over my shoulder :) [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 09:55, 1 February 2019 (UTC)
:::Now I've read your PDF (abeit lightly) I've a much better idea of the structure I think we should have, and in the process I suspect it solves some of our formula problems above. Today I've added a bit of content to introduct object field to the passer by, and I've also moved it - because I think we should have an introduction to the 'standard' approach before presenting an alternative - to make this work I might see how the 'effects' section looks with a similar DoP formula using focal length.[[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 15:27, 2 February 2019 (UTC)
::::Jeff Conrad had a ton of expertise, too, but tended to be more wordy than me over the last 13 years, as you can see by [https://xtools.wmflabs.org/articleinfo/en.wikipedia.org/Depth_of_field how much text he added].  I've mostly just tweaked things, trying to keep the errors out.  If you can come up with a cleaner and leaner article, that will be great. [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 03:58, 3 February 2019 (UTC)
::::: On that topic - how would you feel about (once we've done a bit more cleaning up) putting the article forward for GA? I'm mostly thinking of it because it would be nice to have the article looked at by someone who actually isn't familiar with the topic and it's a nice thing to go for :) [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 13:58, 3 February 2019 (UTC)
::::::I've never engaged in such processes, but yes it could be useful.  [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 17:17, 3 February 2019 (UTC)
:::::::After more cleaning up, I would also support such an endeavor! [[User:MarkH21|MarkH21]] ([[User talk:MarkH21|talk]]) 22:31, 4 February 2019 (UTC)

== Recent changes.  ==

Did a couple of fairly violent changes just now - thought I'd stop to let other people check them over.  

* I added a basic depth of field formula to the top of the article because I think it helps and because otherwise we kind of ambush people at the end. 
* I folded together the overview and 'factors affecting' sections largely to see how it looked - I think it works quite well and I'm inclined to keep it. 
* I removed a couple of images (we have a lot - and we've lost a lot of wordyiness so there's some traffic) and moved others around. 

Comments welcome - going to edit somewhere else for a bit. [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 19:54, 8 February 2019 (UTC)
:Nice! It does look better. Quick comment, do you think there's any way to cut the Table of Contents down a bit, i.e. section/subsection/subsubsections to remove? Seems like a very long TOC relative to the article length now... — [[User:MarkH21|MarkH21]] ([[User talk:MarkH21|talk]]) 11:31, 10 February 2019 (UTC)
:: Thank you!   Re:TOC - it's shorter than it was a couple of minutes ago - I did a few relatively small changes recently. I think that [[Depth_of_field#Other_applications]] is going to get rewritten into a paragraphy, so that will reduce the TOC - I also think that some of the formula are starting to feel like they want to be in the apropreit sections - so that will reduce down quickly.  [[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 20:07, 10 February 2019 (UTC)

== Contining Violence ==

I've been continuing my near-violent changes. I think we are nearly there thought. 

The three things that I think need to be done before submitting for GA review are: 

# Consistent referencing 
# Sort out formula section 
# Thorought proofread. 

I got most of the way thought the referencing a while ago - it only needs a bit more work - particular on the difraction section that came back.  I did a fair amount of work on the formula section today - getting steadily more unhappy with it as I went.  I think we need to get a single consistant mainstream textbook or source and start it from scratch.  At the very least we should be using the same symbols thoroughout the section.  Will investigate the library and come back in a few days to see were we are.[[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 17:17, 17 February 2019 (UTC)
: Oh yeah,  rewrite the lead - the article has changed a lot so it will probably need an overhaul.[[User:Joereddington|Joe]] ([[User talk:Joereddington|talk]]) 17:18, 17 February 2019 (UTC)
::It's looking good.  But an awful lot was lost; did you collect it some place? [[User:Dicklyon|Dicklyon]] ([[User talk:Dicklyon|talk]]) 03:15, 24 March 2019 (UTC)

== Lead, 1st caption, section title and content, POV ==

LEAD<br>
The lead still seems too POVish; but, now the POV is not hidden from the casual reader. Salvaggio et al clearly stated their assumption. The reference and link to "focus stacking" was removed because that article seems to have no reliable basis. Also the 'can't be done by traditional methods' comment was removed as being unsupportable.<br>

1st CAPTION<br>
Reworded the caption<br>

SECTION TITLE AND CONTENT<br>
Changed section title to "Overcomming DOF limitations" to more accurately reflect the intent. Made a few improvements to the wording. Left "focus stacking" in but maybe "image stacking" is a more widely used term (Adobe uses "image stacking") and there doesn't seem to be a reliable reference for "focus stacking".<br>

POV<br>
The article is written from the POV that cameras have a lens axis perpindicular to the sensor plane; that can be very misleading. May want to consider using Conrad, Merklinger, Ray, Wheeler, and others that show what DOF is more generally. The general still applies to the current POV.<br>

[[Special:Contributions/208.54.86.201|208.54.86.201]] ([[User talk:208.54.86.201|talk]]) 02:00, 8 June 2019 (UTC)

{{Talk:Depth of field/GA1}}

== Blurry hearts picture ==

The blurry hearts illustration has more to do with the fact that aperture shape affects the shape of blurry spots; but within the DoF, the blurriness is not noticeable. This is looking like a "how-to" photography-art guide. Seems appropriate for an article that discusses aperture shape and artistic blur; which, might not belong in WP (textbook stuff?). - [[User:NewageEd|NewageEd]] ([[User talk:NewageEd|talk]]) 10:24, 23 January 2020 (UTC)

== Estimate dof in image dimension ==

This is a new logic I have been working on, no publication so far but I will appreciate if somebody is interested in writing an article on this topic. ''Feel free to contact me, thanks.''

he key point is that when we work in the '''image dimension''' instead of the scene the equations become very simple. The size of the focus blur varies linearily along a plane in the image

The relation is;

<math display="block">s = \frac{a}{h} \times d</math>
where:

* a is the numerical aperture
* h is the &quot;altitude&quot; above the plane. This value can be adjusted if the camera is tilted with the cosine of the angle with the plane.
* d is the distance of the point from an origin in the focus plane (where s=0)

The demonstration is [https://github.com/chrisfisheye/dof/wiki/Linearity-of-the-focus-blur-in-the-image here]

A first conclusion is that the focus is at exactly at the middle distance between the near and far dof limit. Again this is true '''in the image''' and along a plane.

Then we have a relation to set the f# for having everything in focus between the focus plane and the near/far limit

<math display="block">f_\# = f \times \frac{k}{h} \times  r</math>
* f is the focal length, h the altitude.
* k is a constant representing the minimum resolution, k =800 is consistent with the results given with common circle of confusions with classic dof calculators
* r is the ratio of the image height between the focus and the near or far limit (for instance 1/3 of the height).

There is also a relation taking into account diffraction:

<math display="block">n = 134 \sqrt{\frac{rf}{h}}</math>
The links are here:

* [https://github.com/chrisfisheye/dof/wiki The theory]
* [https://dof-calculator-55d54.web.app/ DOF calculator]]
* [https://www.youtube.com/watch?v=DTQ2pxel6qA= A video on youtube to use the calculator]  <!-- Template:Unsigned --><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Chrisinparis|Chrisinparis]] ([[User talk:Chrisinparis#top|talk]] • [[Special:Contributions/Chrisinparis|contribs]]) 16:48, 28 January 2024 (UTC)</small> <!--Autosigned by SineBot-->
:: Do not hesitate to give me your feedback, '''I want to do it the clean way. The equations are disclosed''', it is quite simple in fact,it simply uses  a different logic Everything is explained in the links. Feel free to contact me !! 
<BR>