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Old Nov 26, 2003, 10:39 PM   #1
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Default What is the maximum resolution the eye can discern in prints

In other threads in this forum, there seems to be general agreement that the maximum usable resolution (by eye) in a print is about 300 DPI.

However, many yeara ago, I remember seeing some old photographs (probably taken in the 40's and 50's) that were BY FAR the most stunning examples of resolution I have seen before or since. In fact, I don't remember seeing any prints in the last 20 years or so that compare favorably with them.

The photos I am talking about were about 8 x 10 in size and were taken by an 8 x 10 view camera using Panatomic X black and white film with exposures on the order of 30 seconds or so under studio lighting. The prints were really something to behold.

I have no way of knowing the DPI density of those prints, but something tells me they were much higher than 300 DPI. And if they were, then 300 DPI is not the upper limit of the discernment of the eye. Something considerably higher must be. Can anyone shed some light on this resolution issue and perhaps offer a guess about what level of resolution these prints might have been?
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Old Nov 27, 2003, 12:50 AM   #2
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Default Re: What is the maximum resolution the eye can discern in pr

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Originally Posted by exagorazo
In other threads in this forum, there seems to be general agreement that the maximum usable resolution (by eye) in a print is about 300 DPI.

However, many yeara ago, I remember seeing some old photographs (probably taken in the 40's and 50's) that were BY FAR the most stunning examples of resolution I have seen before or since. In fact, I don't remember seeing any prints in the last 20 years or so that compare favorably with them.
Your eyes were just better then.

I've seen studies quoted on the ability for the human eye to discern detail. I don't remember the results exactly, and I'd have to search around for 'em. However, if memory serves, at typical viewing distances (probably around 12 inches, but I don't remember the exact distances used in the studies), the human eye cannot even distinquish the difference between 200 and 300 dpi.

Don't confuse detail captured with dpi or ppi either, and see my response here for the difference:

http://www.stevesforums.com/phpBB2/v...?p=80412#80412

There are other factors that enter into the equation (optical quality of the lens, etc.).

Also, you are limited as to the number of colors (or shades of black/grey) that are accurately represented in digital format, as compared to film (which of course, would go off into a different debate -- shades of color that the eye can distinquish).

Although, I have seen several articles comparing 35mm (and even medium format) film favorably to digital.

Also, film grain begins to enter the equation at larger print sizes. So, there are many convincing arguments (with examples), showing that higher resolution Digital Sensors and Processing, can actually outperform film at very large print sizes (35mm, Medium Format -- not larger formats, yet -- at least with sensors that ordinary humans can afford).

In addition to film grain, quality of the camera's lens, and processing type used; you also need to get into the quality of the optics used to produce the enlarged prints from film. There are many variables when making film versus digital comparisons.

Of course, things like dynamic range of film versus digital enter into the equation, too.

You'll find some interesting articles on the subject at Luminous Landscape. See the links at the bottom of this page (Canon D30 vs. Film; Canon D60 vs. Medium Format):

http://www.luminous-landscape.com/tutorials/dq.shtml

I'm not saying that I concur with all of the conclusions (there is much more to it). After all, the technology used to make the comparisons (scanners, limited in bit depth and dynamic range, format used to store images in, etc.) come into play.

But, it's after 2:00AM here, and it's WAY past my bedtime. I'm sure that more users will "jump into" this subject (it comes up a from time to time in photography forums).
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Old Nov 27, 2003, 4:23 AM   #3
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Default Re: What is the maximum resolution the eye can discern in pr

Quote:
Originally Posted by exagorazo
In other threads in this forum, there seems to be general agreement that the maximum usable resolution (by eye) in a print is about 300 DPI.
It's not just the eye that gives the 300dpi limit, it's the printing paper. If you start with a negative or a high resolution scanned image, print it on photographic paper at various different sizes, then scan these prints and reprint at different sizes, whatever you do you won't see any substantial change in detail betwen a scan from a print at 300-400 dpi, and one at twice that scanner resolution.

It may well be that the 300dpi limitation in everyday printing paper is chosen so that it approximates to the resolution of the typical eye at a typical viewing distance for a small print. Does anyone round here know if this is the case?

Perhaps your old B&W prints were on very fine-grained paper, but visual sharpness is very difficult to assess. Try switching between maximum and minimum sharpening on your digicam. The images will all have the same number of pixels, but the sharpness is an optical illusion created by accentuating edges.

It is possible to get this sort of sharpening in wet photographic chemistry, with clever developers that emphasise the boundaries between dark & light areas. 'High acutance' - is that the term?
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Old Nov 27, 2003, 4:36 PM   #4
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I've heard it said by chemical photographers, that if you shoot big negs (and I guess they're talking 1/4 to 1/2 plate), that a CONTACT print is out of this world and like looking at High def TV. What do you think? VOX
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Old Nov 27, 2003, 4:55 PM   #5
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That's exactly what I'm talking about. Those prints were much clearer and sharper than you could see with your eye if you were standing in the same place!

Modern day prints, even from medium format cameras, are simply not in the same league.

HDTV is a great analogy. The first time anyone sees HDTV, when the picture starts to sink in, they stop and stare in amazement.

Whatever the explanation for those old B&W prints, they obviously had higher resolution than anything I see today.
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Old Nov 27, 2003, 5:19 PM   #6
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When you are as fortunate as I am to see high quality HD pics on a monitor or pro plasma, you wonder what people mean when they talk about their expensive SD TV they just bought with cinema surround sound! Once you've seen it you never forget there's another level. Same with photography, we get used to snappy print quality of film compacts, often not seeing better and being fooled by inkjet dpi specs which rarely deliver to the paper.

It's quite an eye opener to see 3-5 Mpix stills on the best XGA plasma screens, I imagine contact prints if you could make them big enough, would be even better. I guess real edge sharpness is the issue. VOX
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Old Nov 28, 2003, 9:38 AM   #7
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A contact print from an 8 X 10 B&W negative can have a higher resolution than 300 PPI. Iíve done only B&W contact sheets for sorting so I know only what I read about that. That exagorazo can see the difference might be empirical evidence that you can see more than 300 PPI.

But as Alan T points out there can be other factors. You can see the difference in shots taken with large format film compared to 35mm even in a magazine, which is lower in effective DPI than a print. You are obviously seeing something other than DPI.

Iíve read in many places that the 300 PPI is a practical limitation of the photographic process. I would guess though that if the difference were dramatic they would have found a way to improve the process.

There is always the confusion with DPI. Wayne Fulton says it is perfectly correct to use DPI when you are referring to PPI even though it is confusing. The maximum of 300 DPI referred to on a print is 300 pixels per inch.
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Old Nov 28, 2003, 2:24 PM   #8
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............I've read in many places that the 300 PPI is a practical limitation of the photographic process. I would guess though that if the difference were dramatic they would have found a way to improve the process........


But I thought halide crystals and the grain structure of film emulsion was many thousand times per inch and the resolution limitation was modulation index of lenses?

So shouldn't a large 8 X 10 negative exposed to a still life subject in a pinhole camera and contact printed be the Bees Knees in sharpness, to which all Mega Pix should aspire? VOX
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Old Nov 28, 2003, 2:47 PM   #9
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I think there is also the issue of algorithms (not logarithms). Even if the printer/paper combo is able to achieve a resolution equal to film, the printing particles will have to be laid out in an almost random pattern. In terms of recognition, the human eye favours the following in that order: Random patterns, light values (dark/light) and chromatic values (colour). I have seen exhibitions of digital and film photography at the same place, and even though form close-up the detail is similar, I can still pick up the difference between the totally random film, and the structured digital. Hmmmm...
Also, theoretically, the lens/large format of 50 years ago, should not give as sharp a result as an apo lens/6X6 med format film of today. Yet Exagorazo is right: when you look at the two, the large format seems better. Again, hmmmmmmmmmm....there is more to it than numbers me thinks.
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Old Nov 28, 2003, 5:10 PM   #10
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Quote:
Originally Posted by voxmagna
So shouldn't a large 8 X 10 negative exposed to a still life subject in a pinhole camera and contact printed be the Bees Knees in sharpness, to which all Mega Pix should aspire? VOX
Only if the paper on to which you print it has a very fine grain size as well, comparable with the film.

As we all seem to have found out by experiment that modern colour photographic papers can only resolve about 300ppi, I think you'd need to print it on to film to get a trannie, and then view it on a light box.

Of course we're expecting a lot of colour paper, as it has at least three emulsion layers.
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