Exposure and sharpness

pierods · Monday at 6:16 AM

After examining photos from 200+ rolls I shot, first with Nikon and after the obligatory pilgrimage to the Church of our Lady of the Red Dot, I developed a hyphothesis for which I would like an opinion from photographers that have many, many more rolls than I do under their belts.

It's common knowledge that (negative) film is very forgiving of bad exposure. I would like to change this to "Negative film, black and white or color is very forgiving of bad exposure, AT THE PRICE OF SHARPNESS/CRITICAL SHARPNESS".

When going through my photos, I noticed that the sharpest ones also had impeccable exposure, while the rest suffered from either imperfect exposure and/or shutter speeds too low for the focal length used.

The photos that were critically sharp showed no difference with the (correctly exposed) photos taken with the Holy Red Dot Cameras (Red dot owners - they are fantastic cameras and I praise them),

Care to comment?

Thanks.

koraks · Monday at 7:12 AM

'Sharpness is a bourgeois concept'.

Now we have that out of the way.

What is 'sharpness'? Is it resolving power? Or is it something else, for instance something close to 'acutance' in the final image, that relies only in part on an objective parameter like resolving power? Either way, I think you could make a case for the relationship between film exposure and apparent sharpness (I'd say, acutance) in the final image, in the knowledge that (1) the relation is kind of subtle (or the correlation is closer to 0 than to 1) and (2) the effect probably relies quite heavily on how grain/dye clouds act to build image structure, resulting in rendering of fine detail.

Btw, props to you for opening so many cans of worms in one reasonably concise post.

Chan Tran · Monday at 7:19 AM

koraks said:
'Sharpness is a bourgeois concept'.

Now we have that out of the way.

What is 'sharpness'? Is it resolving power? Or is it something else, for instance something close to 'acutance' in the final image, that relies only in part on an objective parameter like resolving power? Either way, I think you could make a case for the relationship between film exposure and apparent sharpness (I'd say, acutance) in the final image, in the knowledge that (1) the relation is kind of subtle (or the correlation is closer to 0 than to 1) and (2) the effect probably relies quite heavily on how grain/dye clouds act to build image structure, resulting in rendering of fine detail.

Btw, props to you for opening so many cans of worms in one reasonably concise post.

Acutance depends a lot on contrast and bad exposure would give poor contrast. Poor exposure also suffers from resolution lost because some part of the image is too dark o too bright and out of the curve.

brbo · Monday at 7:24 AM

pierods said:
The photos that were critically sharp showed no difference with the (correctly exposed) photos taken with the Holy Red Dot Cameras (Red dot owners - they are fantastic cameras and I praise them),

I have trouble understanding this sentence. Do you mean that photos taken with Nikon camera that were properly exposed show same sharpness as Leica and that Nikon photos that were not exposed properly are less sharp than Leica* ones?

* I'm assuming that you take Leica shots as a benchmark and don't necessarily want another Leica flame war

koraks · Monday at 7:26 AM

brbo said:
Do you mean that photos taken with Nikon camera that were properly exposed show same sharpness than Leica and that Nikon photos that were not exposed properly are less sharp than Leica ones?

I read that sentence as "correctly exposed frames looked sharp and incorrectly ones not so much, regardless of camera/lens brand." Perhaps I'm cutting things short too drastically by contending that the whole complication about camera brand could be eliminated from the question so we end up with something that's much more focused and every bit as relevant.

Dali · Monday at 7:28 AM

Were the perfectly exposed pictures more interesting than the others?

Yes > Continue your investigation.
No > Move on.

pierods · Monday at 7:48 AM

koraks said:
I read that sentence as "correctly exposed frames looked sharp and incorrectly ones not so much, regardless of camera/lens brand." Perhaps I'm cutting things short too drastically by contending that the whole complication about camera brand could be eliminated from the question so we end up with something that's much more focused and every bit as relevant.

Exactly so

pierods · Monday at 7:59 AM

So what I meant is that when trying to find some more or less objective way to tell why I had a low yield of sharp/very sharp photos, I used the crude measure of camera price, so I bought a Leica, shot some photos and realized that the problem was not the camera, I should have been more explicit about that.

At that point I formed the opinion that the main factor preventing high/very high sharpness was the fact of not nailing exposure.

But this conflicts with the popular idea that “negative film is very forgiving of exposure”, so at this point my opinion is the one stated above, that is, if you don’t nail exposure, the biggest price you pay is critical sharpness.

So I was asking if this opinion is widespread or I should look elsewhere.

koraks · Monday at 8:07 AM

pierods said:
But this conflicts with the popular idea that “negative film is very forgiving of exposure”

Well, I think that idea is contestable, but it depends on your criteria. So the answer will likely be different for every individual photographer.

Whether variable exposure is the reason why you're not seeing the sharpness in all your photos that you'd like to see - that's a different matter. Exposure plays a role in some way, sure, but there's so much more that contributes to sharpness. I personally like to analyze positive and negative examples and try to formulate/put into words what I'm seeing, i.e. trying to determine what the different dimensions of the phenomenon/problem are. Then, on that basis, maybe set up an experiment (like you did with the Leica kit) to see if I can get an empirical grip on whatever theoretical aspect I determined as relevant.

I find your question interesting because it's close to home for me; I found myself in a similar position as yours recently, where I felt the critical sharpness of my color prints was lacking. I still don't know for sure which factors go into that equation, exactly, although I have a general idea. Raw resolving power is part of it, but interactions within the printed medium (at least in the analog domain) also play a role. The experiment I did was threefold: first, compare my analog workflow to what I could do digitally, using a borrowed camera and lens combination that was known to be capable of yielding good resolving power. When trying that, the issue went away in literally the first print. I then 'downgraded' the camera to the older and much lower-end digital kit I already had, and I found I could still achieve much better acutance (the aspect I was optimizing for) than I could get with my analog workflow. So I then tried the hybrid route and found that I could improve at least for somewhat larger prints (>8x10" from 35mm negs) the acutance of the prints through the scan->inkjet route, over the negative->analog RA4 print route - but I couldn't get even close to what even modest digital equipment easily gives me. This process has given me enough grip on the matter to have another look at the question. Ultimately, our requirements and criteria will probably differ, but the process might be similar.

pierods · Monday at 8:13 AM

Chan Tran said:
Acutance depends a lot on contrast and bad exposure would give poor contrast. Poor exposure also suffers from resolution lost because some part of the image is too dark o too bright and out of the curve.

Thanks.

pierods · Monday at 8:20 AM

koraks said:
Well, I think that idea is contestable, but it depends on your criteria. So the answer will likely be different for every individual photographer.

Whether variable exposure is the reason why you're not seeing the sharpness in all your photos that you'd like to see - that's a different matter. Exposure plays a role in some way, sure, but there's so much more that contributes to sharpness. I personally like to analyze positive and negative examples and try to formulate/put into words what I'm seeing, i.e. trying to determine what the different dimensions of the phenomenon/problem are. Then, on that basis, maybe set up an experiment (like you did with the Leica kit) to see if I can get an empirical grip on whatever theoretical aspect I determined as relevant.

I find your question interesting because it's close to home for me; I found myself in a similar position as yours recently, where I felt the critical sharpness of my color prints was lacking. I still don't know for sure which factors go into that equation, exactly, although I have a general idea. Raw resolving power is part of it, but interactions within the printed medium (at least in the analog domain) also play a role. The experiment I did was threefold: first, compare my analog workflow to what I could do digitally, using a borrowed camera and lens combination that was known to be capable of yielding good resolving power. When trying that, the issue went away in literally the first print. I then 'downgraded' the camera to the older and much lower-end digital kit I already had, and I found I could still achieve much better acutance (the aspect I was optimizing for) than I could get with my analog workflow. So I then tried the hybrid route and found that I could improve at least for somewhat larger prints (>8x10" from 35mm negs) the acutance of the prints through the scan->inkjet route, over the negative->analog RA4 print route - but I couldn't get even close to what even modest digital equipment easily gives me. This process has given me enough grip on the matter to have another look at the question. Ultimately, our requirements and criteria will probably differ, but the process might be similar.

That’s interesting and it gives me a lead. I’m coming from the opposite side (I never print, only scan). I’ll give some not-exceedingly-sharp negatives to a traditional lab for printing on silver paper and see what happens.

retina_restoration · Monday at 9:03 AM

koraks said:
'Sharpness is a bourgeois concept'.

Now we have that out of the way.

Sharpness is only crucial if it’s essential to convey the photographer’s intended message. For some, “critical sharpness” only diminishes the final result and diverts the image in the wrong direction.
Have the wisdom to understand when/if sharpness matters to the image you’re making.

Ivo Stunga · Monday at 9:36 AM

Another possibility - the underexposed negatives are underexposed for a reason - like low light situations, meaning you we're forced to use slow shutter speeds resulting in a slight motion blur.

brbo · Monday at 9:59 AM

Ivo Stunga said:
Another possibility - the underexposed negatives are underexposed for a reason - like low light situations, meaning you we're forced to use slow shutter speeds resulting in a slight motion blur.

That was my line of thinking as well.

But since OP wrote about "negative film being very forgiving of bad exposure" and since we know that this is only valid for overexposure side of exposure...

I mean, we are not discussing whether slow shutter speeds can introduce motion blur? Or are we?!

Arthurwg · Monday at 10:12 AM

All very interesting. My question: How do you know if your exposures are "perfect"? I've recently been shooting with Tri-X in the desert, with high contrast subjects, deep shadows and a wide range of grey tones. Using my Hasselblad on a tripod with mirror lock-up and my 150mm CF Sonar, I see that my exposures were difficult at best, usually problematic and not easy to print in the darkroom. Some of them are quite sharp, but some are less so, and few if any resemble the sharpest pictures I've ever seen. I've also been using a yellow-green filter, and wonder how that contributes to sharpness. And. BTW, what would be the sharpest F-stop on the Sonar? F8?

Arthurwg · Monday at 10:22 AM

koraks said:
'Sharpness is a bourgeois concept'.

Maybe so, but one non-bourgeois photographer that immediately comes to mind, Edward Weston, did not suffer from a lack of sharpness. Josef Koudelka, another BoHo, also made sharp pictures.

Saganich · Monday at 10:41 AM

I notice that exposure (being as correct as possible) and "sharpness" have correlation, even that 1/30th motion blur looks better well exposed. I try not to underexpose for the sake of a bit more shutter speed...rather bring the elbows in and click on the exhale.

loccdor · Monday at 11:08 AM

Resolution/sharpness/acutance are always being limited by the weakest link in a complex system. I found that when I identified and improved my particular weakest link, the weaknesses in parts of the system I could not previously see started to show.

The discussion on exposure's contribution to sharpness and of motion blur's degradation of sharpness are two related, but different, topics. It would be good to figure out which one we are talking about here and stick to that.

pierods · Monday at 11:30 AM

Ivo Stunga said:
Another possibility - the underexposed negatives are underexposed for a reason - like low light situations, meaning you we're forced to use slow shutter speeds resulting in a slight motion blur.

brbo said:
That was my line of thinking as well.

But since OP wrote about "negative film being very forgiving of bad exposure" and since we know that this is only valid for overexposure side of exposure...

I mean, we are not discussing whether slow shutter speeds can introduce motion blur? Or are we?!

When going through my shots, I realized that (I had just picked up photrography) in many shots I had overestimated my ability to shoot at speeds under 1/focal length. So excluding those shots, the other possibility was over/underexposure.

pierods · Monday at 11:31 AM

loccdor said:
Resolution/sharpness/acutance are always being limited by the weakest link in a complex system. I found that when I identified and improved my particular weakest link, the weaknesses in parts of the system I could not previously see started to show.

The discussion on exposure's contribution to sharpness and of motion blur's degradation of sharpness are two related, but different, topics. It would be good to figure out which one we are talking about here and stick to that.

Exposure

pierods · Monday at 11:33 AM

Arthurwg said:
All very interesting. My question: How do you know if your exposures are "perfect"? I've recently been shooting with Tri-X in the desert, with high contrast subjects, deep shadows and a wide range of grey tones. Using my Hasselblad on a tripod with mirror lock-up and my 150mm CF Sonar, I see that my exposures were difficult at best, usually problematic and not easy to print in the darkroom. Some of them are quite sharp, but some are less so, and few if any resemble the sharpest pictures I've ever seen. I've also been using a yellow-green filter, and wonder how that contributes to sharpness. And. BTW, what would be the sharpest F-stop on the Sonar? F8?

Which ones were less sharp?

pierods · Monday at 11:38 AM

Just to be clear: I am talking about those photos that bring out peak sharpness in your setup - so I am equating peak sharpness (given accurate focus and high shutter speeds of course) with very good exposure.
So the saying "negative film is very tolerant of bad exposure" would have the addendum "and then get so-so sharpness".

koraks · Monday at 11:47 AM

How are you evaluating the result, btw? Prints, monitor? If prints, color or B&W? Optically made, or inkjet? I find that 'sharpness' can work really very differently depending on the medium.

BrianShaw · Monday at 12:16 PM

What is your definition of "bad" in "bad exposure"? Is that within or beyond the "normal latitude" of the film, and how is "normal" defined/determined?

loccdor · Monday at 12:45 PM

There are scanners that introduce noise and lack of clarity in dense overexposed negatives because the sensor is not very sensitive or the light source isn't bright enough.

Then there is a lack of clarity caused by pushing everything up into the shoulder of the film itself. Two different phenomena. But you could potentially be experiencing both of them at the same time.

Exposure and sharpness

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