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# Thread: Viewing distance and perspective -- what's the basis?

1. ## Viewing distance and perspective -- what's the basis?

I've occasionally read, including in Ansel Adams' writings, that viewing a print from the same distance as the lens' focal length (multiplied by enlargement factor if applicable) provides the most appropriate perspective.

What is the basis for this idea? I'm just asking out of curiosity. Why does the focal length of a lens determine how far away we should stand from a print?

And I also don't understand why this rationale is used in support of LF and ULF contact prints, whereas the same image / final print size should demand the same viewing distance irrespective of format (i.e. a format that requires 2x as much enlargement will require 1/2 the focal length -- so the viewing distance will be identical in the end).

2. Dear Paul,

The logic is that the angle subtended by each element in the picture should be the same as the angle subtended at the camera by the same element in the original scene.

Often, this gives a unique three-dimensionality to the image, the 'magic' perspective. The eye/brain can accommodate quite wide variations, so the 'magic' is seen across a few inches either side of the 'magic' distance, but outside that range, it is normally lost.

Small pictures are normally examined from closer than big ones, so (for example) a 127mm/5 inch lens on quarter plate implies a viewing distance of 5 inches while a 300mm/12 inch lens on 8x10 implies a viewing distance of 12 inches.

This also explains why small formats often use 'long standard' lenses, e.g. 6 inch on quarter plate and 50mm on 35mm: viewing distances for 'magic' perspective would be inconveniently short otherwise. Thus a 5x enlargement off 35mm shot with a 50mm lens should be viewed from 250mm or 10 inches.

Cheers,

Roger

3. Makes sense, Roger. I wonder if most people intuitively look from this 'magic' distance as they move in and out from a gallery photo.

The strange thing is it implies very close viewing distances for wide angle shots and strangely far viewing distances for telephoto shots. I mean if you use a 47mm lens on 4x5 and enlarge to 8x10, that means you're looking at an 8x10 print from 3 1/2 inches away. Or if you use a 600mm lens on 35mm, a 4x6 print would be viewed from 8 feet away.

Seems to be a bit impractical except for normal lenses

There must be a similar phenomenon for drawings and paintings, assuming any perspective is consistent across the picture. I mean the print doesn't know if it's passed through a lens or not.

4. Originally Posted by DrPablo
There must be a similar phenomenon for drawings and paintings, assuming any perspective is consistent across the picture. I mean the print doesn't know if it's passed through a lens or not.
I have long admired "Flaming June" in the Ponce Museum of Art, and have always believed that, given it's square format, it must have been painted from a photo taken by a Hasselblad with about a 150mm lens.

The fact that it was painted in 1895 is but a small flaw in my reasoning.

5. It must always include enlargement factor. After all, a 4x5 contact print should be viewed at the same 'size' as an 8x10 enlargement.

The proper viewing distance is always important in prints and always includes the size of the final image.

PE

6. All these formulae and stuff are wonderful things to know. but we all know that the appropriate distance for a photographer looking at another photographer's photograph is to have your nose right on the glass.
If you are of an appropriate vintage, you will either take your glasses off or push them up on your forehead before you stick your nose on the glass.
Come on, you know this is true.

7. I don't have the text in front of me, but if I recall correctly, Adams is talking about the viewing distance at which the perspective would look natural, which is not necessarily the best or expected viewing distance. For instance, if you look at an image made with an ultrawide lens from a very close viewing distance, the perspective will look natural, but if you look at it from a more typical viewing distance, it will appear exaggerated (i.e., things will appear to be farther apart from each other than they are), as the photographer probably intends.

8. I prefer to view a print at about double the distance of the diagonal or so. It isn't a rule or anything that I know of, just seems about right.

When my 8x10 contacts are hung, it is fun to overhear print sniffers, with their nose on my print- "Wow, that's incredible detail. I wonder what kind of printer he uses?"

9. Originally Posted by Joe Lipka
All these formulae and stuff are wonderful things to know. but we all know that the appropriate distance for a photographer looking at another photographer's photograph is to have your nose right on the glass.
If you are of an appropriate vintage, you will either take your glasses off or push them up on your forehead before you stick your nose on the glass.
Come on, you know this is true.
I found myself viewing some original, very large, Brad Washburn ariel photos of mountains from just a few inches away (5 or 6). It was the only way to appreciate the fine detail (w/glasses off).

P.S. I have a close cousin who helped design one of Mr. Washburns ariel camera film advance mechanisms - not such an easy task with LF roll film.

10. [QUOTE=panastasia;569941]I found myself viewing some original, very large, Brad Washburn aerial photos of mountains from just a few inches away (5 or 6). It was the only way to appreciate the fine detail (w/glasses off).

P.S. I have a close cousin who helped design one of Mr. Washburn's aerial camera film advance mechanisms - not such an easy task with LF roll film

That's aerial photos and camera, not a ariel (jupiter moon, I think), excuse my poor spelling.

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