The Falacy of FF Cameras having Flatter DOF

[george013]

AND



I concur with both responses.

I also note that there have been several previous threads at CiC where there has been a request for a definition of the term “Perspective”.

Sometimes, subsequent to the correct technical definition having being given (as per in this thread by Philip and Dave) there is disagreement or argument about that correct technical definition.

I don’t see a lot of point in continually debating a definition which is established in respected Texts and Curricula.

WW

One remark. This "perspective" is something else as the suggestion of a third dimension. It's the "point of view". It's the state of your position and viewing direction.
http://www.oxforddictionaries.com/de...sh/perspective
http://www.oxforddictionaries.com/de...us/perspective

When accepting this, "one can change the point of view to play with perspective", the illusion of a third dimension. It's sounds funny to say "one can change perspective to play with perspective".

Why I asked this is that I do think perspective as the illusion of a third dimension does change when cropping an image, or using a telelens. There have been many discussions on the net and here, and nobody could explain that 2 different things where meant. I know now.

George

This article was when I saw the light
http://www.lightstalking.com/point-of-view/

In this article I’d like to consider the POINT OF VIEW. You might also know it as the photographer’s perspective, vantage point or, simply, where you are standing at the time of taking the photo.

[William W]

Hi George,

That's good that you have an explanation and you are happy with that explanation.

I don't understand the confusion, because the article that you cite clearly mentions (my paraphrasing) "the photographer's perspective is a place where he is standing and if we change that place, then we change the perspective".

The Photographer's (or the camera's) "point of view" means the same thing: it is where he is standing. Where the camera is standing defines the "perspective" of the shot. It is really that simple.

*

I have no idea where you are getting this phrase "the illusion of a third dimension".

If you want a definition of "Perspective", as it applies to Photography, then it is probably best to consult well regarded technical texts or manuals, rather than on line dictionaries.

Again my paraphrasing, this time simply because I don't have my library at hand - I am moving and my reference books are in storage, but I am sure that I have quoted verbatim this definition before and I think it was as an answer to you previously questioning the definition of "Perspective" . . .

From Manual of Photography (Formerly The Ilford Manual of Photography) Various Editions:

"The Perspective of the Shot is determined by the Camera's Viewpoint relative to the Subject(s).

"The Camera's Viewpoint is defined as: (1) the Subject Distance and (2) Camera Elevation relative to the Subject.

*

There are numerous other well respected texts and authors, (Hedgecoe; Adams; Langford, et al) and also numerous Technical Curricula around the world which adhere to the same definition (City and Guilds; Leica; NYC, et al)

And importantly: "Perspective", does NOT change by cropping or using a different Focal Length of Lens.

WW

[george013]

Hi George,

That's good that you have an explanation and you are happy with that explanation.

I don't understand the confusion, because the article that you cite clearly mentions (my paraphrasing) "the photographer's perspective is a place where he is standing and if we change that place, then we change the perspective".

The Photographer's (or the camera's) "point of view" means the same thing: it is where he is standing. Where the camera is standing defines the "perspective" of the shot. It is really that simple.

*

I have no idea where you are getting this phrase "the illusion of a third dimension".

If you want a definition of "Perspective", as it applies to Photography, then it is probably best to consult well regarded technical texts or manuals, rather than on line dictionaries.

Again my paraphrasing, this time simply because I don't have my library at hand - I am moving and my reference books are in storage, but I am sure that I have quoted verbatim this definition before and I think it was as an answer to you previously questioning the definition of "Perspective" . . .

From Manual of Photography (Formerly The Ilford Manual of Photography) Various Editions:

"The Perspective of the Shot is determined by the Camera's Viewpoint relative to the Subject(s).

"The Camera's Viewpoint is defined as: (1) the Subject Distance and (2) Camera Elevation relative to the Subject.

*

There are numerous other well respected texts and authors, (Hedgecoe; Adams; Langford, et al) and also numerous Technical Curricula around the world which adhere to the same definition (City and Guilds; Leica; NYC, et al)

And importantly: "Perspective", does NOT change by cropping or using a different Focal Length of Lens.

WW

Google on perspective and view the images.
http://www.oxforddictionaries.com/de...sh/perspective

I can say I choice a point of view to add perspective to an image..

And importantly: "Perspective", does NOT change by cropping or using a different Focal Length of Lens.

This one counts when you're meaning point of view with pespective. But not when you mean the suggestion of a third dimension.
We've discussed this before. I'm now aware of different definitions of perspective.

https://archive.org/stream/Manual_of...raphy_djvu.txt

Perspective

The term perspective is applied to the apparent
relationship between the position and size of objects
when seen from a specific viewpoint, in a scene
examined visually. The same principle applies when a
scene is captured by an imaging system, the only
difference being that the camera lens takes the place
of the eye. Control of perspective in photography is
therefore achieved by control of viewpoint.

Painters or digital photographers are not limited in
this way; objects can be placed anywhere in the
picture, and their relative sizes adjusted at will. If, for
example, in depicting a building, they are forced by
the presence of other buildings to work close up to it,
they can nevertheless produce a picture which, as far

With size is meant the size on the image. Or the magnification. Big differences in magnification suggests more depth, the third dimension.

George

[ajohnw]

I like that post Dan but I think one DOF aspect needs expanding on.

One of the problems with this area is comparing like with like. My impression is that it gets bogged down with what's on the sensor. The only meaningful like with like is the final result when it's viewed. In that case in order to produce a more or less identical image as a FF camera the crop camera must have a greater dof because it will need more enlargement to reach what ever size the final image is.

So in my case with M 4/3 I need blur levels that are approximately 1/2 what a FF camera can produce for the same framing. I played with the settings of the calculator again because it can show that I can't match a FF camera precisely. This time the blur for the same size final image gets greater than FF at some particular distance. Prior to that it's very similar. The previous one was a touch less and and then very similar. Difference under 1/2 stop. In this case the focal lengths are very similar but as Grahame mentioned for the same framing the camera would have to be further away - so what. It might or might not be a problem.

http://howmuchblur.com/#compare-1x-8...m-wide-subject

Here is what happens if the M 4/3 lens is changed to 45mm so similar to the 85mm FF lens. Bearing in mind that for the same final image size the blur does need to be less and is roughly 1/2 that of the FF.

http://howmuchblur.com/#compare-1x-8...m-wide-subject

Actually if I could put 42.5mm in the calculator the blur would be 1/2. Not surprising really as that's how the sums work.

On perspective I had a number of lectures from Royal Society people years ago on the nuts and bolts of cameras and the effects lens focal lengths and and apertures etc. I can't really be expected to accept any other definition other than the one I gave but if others want to call that something else or see perspective as something different that's fine by me. I don't see that the term has any bearing on the other factor which is framing - it just has an effect on the apparent depth that will be seen in the final image. Distortions relating to an eye view too in some cases.

John
-

I'll quote myself Bill.
So bearing that post in mind when you posted a shot with a blurred background and stated that it would need such and such an aperture on crop just how did you enlarge the crop shot so that it was the same size when viewed as the full frame shot without increasing the apparent blur in the crop shot?

Perspective for me still remains as I stated. If others want to see it as framing that is fine by me. It leaves a bit of a problem though. Just what term is available for broadly talking about focal length effects on images in terms of apparent 3D depth.

John
-

[Dave Humphries]

It leaves a bit of a problem though. Just what term is available for broadly talking about focal length effects on images in terms of apparent 3D depth.

Depth perception?


Now you're talking about the compression of depth seen when using a telephoto versus the expansion of depth when using a wide to ultra wide angle lens. Fundamentally, it still equates the relative sizes of two objects at different distances from the camera when the shot was taken.

Although I would proffer that like Darlene, you are rolling the focal length and camera position together - and overlooking that it is the shooting position alone that is actually determining the perspective. Just that in order to see the object of the image, one uses a telephoto to achieve the shot in some circumstances, or a UWA lens in others.

[ajohnw]

Well all I can say is that some web pages are aware of the whole area. All I have really said is that the focal length of the lens used will have a bearing on the apparent perspective of the shot. Framing on it's own is far more limited.

USA Navy - Illustrates it but no mention of lenses. Maybe that is in there advanced stuff. This is basic.

http://photoinf.com/General/NAVY/Perspective.htm

And this one which does have clear indications of lens focal length effects on the page.

http://www.school-of-digital-photogr...otographs.html

No Dave I am not. The other aspect mentioned is framing which may also have an effect on perspective such as very low down very wide angle scenes with features in the foreground - done because at normal camera position the perspective generally isn't pleasing to the eye. It's effect can also be bad such as converging verticals unless that is wanted or shooting up some ones nose as the navy booklet mentions - usually not a good idea.

John
-

[William W]

. . . when you posted a shot with a blurred background and stated that it would need such and such an aperture on crop just how did you enlarge the crop shot so that it was the same size when viewed as the full frame shot without increasing the apparent blur in the crop shot?

I didn't "enlarge" anything.

I have stated several times that I am referencing the SAME FRAMING.

Please see previous posts for a definition of “FRAMING” – it is what you achieve in the camera viewfinder – nothing to do with “cropping” or “enlarging”

*

Perspective for me still remains as I stated. If others want to see it as framing that is fine by me. It leaves a bit of a problem though. Just what term is available for broadly talking about “focal length effects on images in terms of apparent 3D depth”.

Firstly I have no idea where you get the idea that PERSPECTIVE is dependent upon FRAMING,

Specifically and for clarity of meaning: I did never write that.

Secondly you mentioned previously that you were lectured on the topic of “Perspective” by members of the “Royal Society” – I assume that is members of the Royal Society of Photography. If those members gave you any instruction on the definition of Perspective other than what I have outlined, then I can only conclude that they are ignorant of the technical definition of the term “Perspective” and I would refer them to the statutory courses as were or perhaps are still are available as courses of study via London “City and Guilds”.

Thirdly, the most common technical terms used to describe “focal length effects on images in terms of apparent 3D depth” are:

- compression
- foreshortening
- elongation

WW

[pnodrog]

The following two shots have identical perspectives (same photograph cropped). However the great unwashed public and many novice photographers could be excused for concluding they had different perspectives.....

I think the problem is the difference in how people use language to express themselves. Exact or general usage of a word.

[ajohnw]

The only thing that is relevant is the final image Bill and if framing is the same and the final size isn't the same the results are meaningless.

The only real advantage full frame has in this area is the degree of enlargement that could be applied to the image. It might be thought that this applies to M 4/3 and APS too but that aspect isn't as simple as it might first appear to be.

Plus I can't help adding that the 3 terms you mention in relationship to lens focal length are perspective effects. No comment on your view of my tutors.

John
-

[William W]

. . . I think the problem is the difference in how people use language to express themselves. Exact rather than general usage of a word. . .

Yes. I agree.

I am reasonable certain that have enunciated several times during this conversation, that I refer to the technical definition of the word "Perspective" - as it applies to Photography.

*

We can roll of several examples of images similar to yours (Paul) an also to Philip's - to show this point about how CROPPING does NOT change "Perspective".

viz:


Same "Camera Viewpoint" was used to make images with Lenses of Focal Length: 16, 20, 35, 70, 100, 135, 200, 300, 400

*

then:


Each image was cropped to mimic the FRAMING of the shot made with the 400mm Lens

WW
All Images © AJ Group Pty Ltd Aust 1996~2016 WMW 1965~1996

[ajohnw]

I think the problem is the difference in how people use language to express themselves. Exact or general usage of a word.

I wouldn't disagree with that at all Paul. Clarity is an important aspect of language which is why I will stick to my view of the use of the word as it's very clear to me. Purely 3D effects. As I see it framing is mostly where I choose to position myself. Perspective is largely what focal length I use from that position - that can't be done with the feet. Composition is something else that is likely to relate to framing. Perspective will shift according to lens angle but usually in an undesirable manner. Camera height is another that will shift perspective in a different fashion and may be either good or bad. Focal length - purely 3D irrespective of the others and also a pure depth effect.

John
-

[William W]

. . . The only thing that is relevant is the final image Bill and if framing is the same and the final size isn't the same the results are meaningless.

I really have no idea what you mean by this.

My point is and has always been that APS-C Format and 135 Format cameras are capable of producing different results.

The example exercise I provided stipulates that framing of the two images is the same. I have no idea what "final size" means but the final image sizes ARE THE SAME.

Simply put - you CANNOT get the same shallow DoF using and APS-C Camera as you can using a 135 Format camera. . . an that is why the results are DIFFERENT.

Have you tried the exercise that I outlined?

*

The only real advantage full frame has in this area is the degree of enlargement that could be applied to the image. It might be thought that this applies to M 4/3 and APS too but that aspect isn't as simple as it might first appear to be.

If you want to believe that, then please do so: I shall not try any more to prove that is incorrect.

*

Plus I can't help adding that the 3 terms you mention in relationship to lens focal length are perspective effects.

They are not.

But, if you want to think of it that way the that’s fine by me.

Again we seem to be at the limit of discussion and you seem refuse to accept (or investigate) technical definitions as per standard texts and world-wide recognized courses of technical instruction on Photography, so that’s where you are and that’s fine: and thus we must agree to disagree on this point too.

Have you researched the definition of "Perspective" in accepted Standard Photography Text books or as per the courses offered by London "City and Guilds"?

*

No comment on your view of my tutors.

On this point, and for the reasons outlined above, it seems we also must agree to disagree.

WW

[William W]

. . . Clarity is an important aspect of language which is why I will stick to my view of the use of the word as it's very clear to me. Purely 3D effects.[/B][/U] As I see it framing is mostly where I choose to position myself. Perspective is largely what focal length I use from that position - that can't be done with the feet. Composition is something else that is likely to relate to framing. Perspective will shift according to lens angle but usually in an undesirable manner. Camera height is another that will shift perspective in a different fashion and may be either good or bad. Focal length - purely 3D irrespective of the others and also a pure depth effect.

These definitions are certainly way out of kilter with the technical terms that have been used and taught by educated and experienced Photographers, for many decades.

WW

[William W]

. . . Now you're talking about the compression of depth seen when using a telephoto versus the expansion of depth when using a wide to ultra wide angle lens. Fundamentally, it still equates the relative sizes of two objects at different distances from the camera when the shot was taken.

Yes.

WW

[William W]

I am neither being rude nor disrespectful, but unless a previously untapped nuance is introduced, then I am at my limit of ability to contribute to this conversation.

Good-night.

WW

[ajohnw]

The problem with most information on blur in particular Bill that it infers that people who use various sizes of crop camera can not produce the same results as a full frame camera can. That is not a good idea as beginners will just assume that they can't. Blur to be really effective has to be related to the final size of the image that is finally viewed. That will even effect what degree of it can be seen in the viewfinder. In the extreme it's likely to not even be clearly visible in the view finder so tape measures and calculator are needed. Those ignorant people I mentioned could also cope with that. I often wish I could remember the sums and the suggestions about degree of blur to obtain a specific effect. Especially the suggestions.

So in a nutshell yes more blur will be seen through viewfinders but when ever that is mentioned the scaling aspects for the final print or web shot should also be mentioned as these are what people will actually see at some point.

John
-

[george013]

...
I am reasonable certain that have enunciated several times during this conversation, that I refer to the technical definition of the word "Perspective" - as it applies to Photography.
...

You mentioned the Ilford Manual of Photography as an example. I gave the link to it. Doing a search for perspective within that document shows me that that manual perspective solely relates to the suggestion of a third dimension. I do advise to all to do that search.

From that same manual, I quoted before

The term perspective is applied to the apparent
relationship between the position and size of objects
when seen from a specific viewpoint, in a scene
examined visually.

The scene examined visually is the image or the framing. Therefore the pictures of Paul in post 68 do have a different perspective.

George

[William W]

The problem with most information on blur in particular Bill that it infers that people who use various sizes of crop camera can not produce the same results as a full frame camera can. That is not a good idea as beginners will just assume that they can't.

Well I have never mentioned "blur".

I did mention DoF, several times.

With reference to DoF it is indeed a FACT that: "people who use various sizes of crop camera can NOT produce the same results as a full frame camera can."

*

This fact is demonstrated in Post #55.

This fact is referenced in "Equivalence in Photography", James Joseph (op cit).

This fact can be demonstrated by using any reputable DoF calculator and that has also been mentioned in Post #55.

This fact can be proved by Mathematics, beginning at First Principles of the Calculation for DoF.

*

It is entirely your choice to refuse to acknowledge these facts - and that's fine.

Accordingly I do suggest that we call it quits in this conversation and I also suggest that maybe you might do the exercise that I outlined and also research the definition of "Perspective" from a few reputable sources, as I also suggested.


WW

[William W]

You mentioned the Ilford Manual of Photography as an example. I gave the link to it. Doing a search for perspective within that document shows me that that manual perspective solely relates to the suggestion of a third dimension. I do advise to all to do that search.

From that same manual, I quoted before:

The term perspective is applied to the apparent
relationship between the position and size of objects
when seen from a specific viewpoint, in a scene
examined visually.

The scene examined visually is the image or the framing. Therefore the pictures of Paul in post 68 do have a different perspective.

George

No.

Paul’s images do NOT have a different perspective

Best if you quote the whole passage.

What you quoted in Post#63, I do not think is the whole passage anyway: but it is enough to prove your statement above as incorrect. .

Here is what you originally quoted in Post #63. Note now my bold for emphasis and the proof that by this definition your statement above is incorrect:

Perspective

The term perspective is applied to the apparent
relationship between the position and size of objects
when seen from a specific viewpoint, in a scene
examined visually. The same principle applies when a
scene is captured by an imaging system, the only
difference being that the camera lens takes the place
of the eye. Control of perspective in photography is
therefore achieved by control of viewpoint.

Painters or digital photographers are not limited in
this way; objects can be placed anywhere in the
picture, and their relative sizes adjusted at will. If, for
example, in depicting a building, they are forced by
the presence of other buildings to work close up to it,
they can nevertheless produce a picture which, as far

Also from memory that quote is in a general chapter: a chapter titled something like “Lens and Optics” has the definition similar to my paraphrase.

WW

[george013]

William,

I like your link so much. I'll buy that book, it's still printed.
Pity the link I found doesn't show pictures.

Perspective

The term perspective is applied to the apparent
relationship between the position and size of objects
when seen from a specific viewpoint, in a scene
examined visually.

What is meant with the size of an object? My finger has a certain size,. Doesn't change when holding it before my eyes. But it does change "in a scene examined visually". A different experience holding my finger close or far. The relative size is changing. But relative to what?? To other subjects in that view. One can also say that the magnification is changing. And than we can say relative to the view we have.

The same principle applies when a
scene is captured by an imaging system, the only
difference being that the camera lens takes the place
of the eye. Control of perspective in photography is
therefore achieved by control of viewpoint.

An important one. It mentions "a scene (is) captured by an imaging system".
The result is a photo in our case. That physical product, that print, is made from a certain position, a certain direction and a certain angle of view. All objects have a magnification relative to that borders, the size of the picture, or film/sensor.
That a certain perspective is gained by a certain viewpoint is logic. It doesn't mean they are the same. The choice of your viewpoint is a tool to archive a certain perspective.
Since cropping is changing the angle of view, we can say that the perspective is changing.

Painters or digital photographers are not limited in
this way; objects can be placed anywhere in the
picture, and their relative sizes adjusted at will. If, for
example, in depicting a building, they are forced by
the presence of other buildings to work close up to it,
they can nevertheless produce a picture which, as far

It doesn't go further.

I still advis all of you to do a search on "perspective" in that link. https://archive.org/stream/Manual_of...raphy_djvu.txt

George