Dealing with under/over-exposed & -developed negatives; scanning or enlarging

Yezishu

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“The transmission coefficient of the developed film is proportional to a power of the reciprocal of the brightness of the original exposure.”
You see, this is not a simple linear relationship, so you can’t just invert it directly to get the best result. It will also deviate as the exposure and development stray from optimal conditions.
 
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dcy

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Can you gift her a camera with a light meter?

My wife's camera is too automated. It reads DX codes. Foma doesn't have DX codes, and if it had one it'd say 400 instead of 200. I went on Amazon and got a set of DX code stickers that read ISO 250 and gave them to her to sick on Foma 400 canisters.
 

albireo

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dcy said:
I can confirm that this was my intent.



Exactly. My holiday photo is my holiday photo. I can't take it again. If I screwed up the development or exposure, I still care about how much I can salvage.
Click to expand...

Ah, but then you'll have no issues at all. Yes, I agree with everyone else saying that scanning those screwed up negatives will in fact return an image, a document, and will 'salvage' your holiday snaps.

I mean, if you wanted, and the purpose was restoration of poorly exposed or processed irreplaceable analogue content, you could skip LR & curves altogether and feed those negative scans to Midjourney or Dall-E or Leonardo and get a great usable, actually more than usable, document. I mean if AI is now good enough to reveal new insights on the Dead Sea Scrolls, it's more than good enough to breathe new life into our thin negatives.

I was talking about something else entirely, and perhaps trying to stimulate a broader discussion on building a densitometric optimality theory for hybrid photography/scanned film, which is currently missing, and which needs to rest on foundations as solid as those existing for the full wet darkroom film photography chain and not hearsay.

So please do carry on, and all the best for your discovery journey!
 
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MattKing

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Alan Edward Klein said:
Kodak claims Ektar and Tmax films are better for scanning. Anyone know why?
Click to expand...

At least partially because those films were created after the commercial processing market moved toward "scan plus print from the scan" norm from that which existed previously.
Among other things, the negatives tend to dry flat and to be easily handled.
 
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dcy

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Matt said that certain types of exposure or development mistakes might be easier to manage in the darkroom and others digitally. There is nothing wrong with me wanting to understand why that would be the case. You telling me to use an AI to generate images instead of learning how to handle unintentionally poor negatives can reasonably be interpreted as... uhmm... showing me the door.
 

MattKing

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I would stress that I really was talking about negatives at the margins.
I may as well repost this off-shared image - from a negative that upon first glance looks very, very thin.


That happens to be a scan from the negative. It also prints well in the darkroom.


I don't have a great example of a very dense negative to compare it with, but this one goes at least part of the way:

Where Did They Go?

From nearly 14 years ago
43c-2011-08-12-res 1200.jpg
That happens to be scanned from a print (If I remember correctly).

I post these two as examples merely to make it clear that both very thin and very thick negatives can be handled well both ways. It is only when I get right out on the edges of usability that I encounter a bit of preference.
 

Yezishu

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There are also some interesting discussions in a neighboring thread:
"A low contrast scene can easily tolerate 1 stop under and 3 stops overexposure without a significant problem, but a high contrast scene will have 0 stops."

Fujicolor 100

Nice. I am not surprised at all. Somehow this film always felt like being on another level for me. A step above Portras and Fuji's own 400H Pro. I have my last 4 rolls sitting in the freezer and I keep hoping for its return and hopefully even a 120 version. It is indeed an excellent film (so...
www.photrio.com

I’m hoping experienced users to generously share some insights on the exposure latitude of modern films for learning. How much can we over- or underexpose and still without big difference after standard development and scanning? Not only exposure error, but the presence of both highlights and shadow details is also an related issue. @retina_restoration convincingly mentioned that Tri-X can handle up to 2.5 stops of overexposure, which is very informative. Some C41 black-and-white films like XP2 even claim usable speeds from ISO 80 to 800:

Controlling contrast in B&W film

If you want to try DYI you can try divided D 23, D23 will tame the grain, in the divided form will also compensate for high contrast situations. From Chatbot but both AA and Minor White provided the forumal as well. The D-23 developer formula, used in black and white film development...
www.photrio.com

If exposure errors go beyond these limits, can push or pull processing in the darkroom dig more detail? While changing development time doesn’t create new information, it can sometimes reveal details hidden by standard processing. Adjusting the developer can also dig. For example, I recently used a low-contrast developer and extended development time to shoot microfilm rated at ISO 8–10 at ISO 64–100 before tonal compression became too noticeable. With standard development, density would be too low, but the information(not all, but some) was still present on the film.

Similarly, how much can scanning do for over- or underexposed negatives? Understanding the practical exposure latitude under different conditions—knowing when only minor adjustments are needed versus when “extreme contrast adjustments” are required—is very helpful. For instance, if my camera’s meter is normally off by +1 to -2 stops, I’d like to know whether the typical negative film can handle this error range or if I have to bring a separate light meter, or I need to be particularly cautious in low-light situations where I know my meter isn’t so accurate.
 
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koraks

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dcy said:
Can you gift her a camera with a light meter?
Click to expand...
She has a Canon EOS 300 with a perfectly fine light meter; I've verified it works as it should. It's just that she lacks the experience to consistently nail exposures under the circumstances she uses the camera in, which range from snapshots while skiing in sunny-16 conditions and snow everywhere to Christmas dinner around the table in EV-sub-zero conditions. Mind you, between the first and the most recent roll there's a world of difference already; she's learning! But she can't afford (esp. time-wise) to practice a whole lot, so I expect there will be many more frames where a scanner and a dramatic twitch of the curves will save aunt E. from the blackness of zone I.

dcy said:
Matt said that certain types of exposure or development mistakes might be easier to manage in the darkroom and others digitally. There is nothing wrong with me wanting to understand why that would be the case.
Click to expand...

Certainly; I'm glad we've been able to establish the scope of your question as you intend it and it's a perfectly fine and relevant question to discuss. Anyone who wants to explore a different/adjacent/broader topic is free to create a thread bout that, too.
 

Mr Bill

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Hi, I've posted about some pro portrait/wedding films over the years; here's one such...

What's the exposure latitude of Color Neg film?

Somehow, I don't think Drew photographs weddings. The initial answer to the question posed in the title is a question - "For which photographic usage?" If you are controlling the light, and aiming for extremely accurate and/or dependable colour rendition, Drew is completely right. If you are...
www.photrio.com

If you count down to the 8th paragraph, I said that our "good" exposure range on Portra 160 NC ran from about 1 f-stop underexposed to about 3 or 4 f-stops overexposed.

Within this range, after hand balancing everything to match (optically printed onto an appropriate professional color paper) that a professional color corrector essentially could not tell them apart. These were full-tonal scale portrait scenes, 3 or 4 models with a variety of skin complexions and hair colors. Fabrics from black to white and several of the strongest colors from a local fabric store. And several color test charts. EVERYTHING in the scene was a near identical match.

If one was willing to give up a bit they could say that one more f-stop in both directions was "usable." (But we we would not consider it so.) At 2 stops underexposed the darkest parts of the scene, black fabric in shadow, was no longer solid black, and was getting grainy. At 5 stops overexposed the strong colors were taking on a somewhat pastel appearance.

I should point out that these tests were shot using professional-grade studio flash, which is what Portra film is balanced to. If one were to use a different color temperature for lighting at least one of this film's color-sensitive layers would be offset from the others, and consequently the usable exposure range would be somewhat reduced.

I know that there are a number of internet posts/videos where some "experimenter" finds contrary to this. I don't know what they're doing, but suspect that it's often a scanning issue. Or, for non-professional film processing, perhaps sparse development is an issue.
 

Bill Burk

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Very nice!
 

Yezishu

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Thank you so much for your detailed posts—this is exactly the information I was looking for! I will search for more. I truly admire the time and effort you put into such rigorous testing.

There are very few recent posts or videos that cover these aspects in detail, and many 'experiments' online are quite rough. Useful advice rarely goes beyond “add one stop of exposure to be safe.” Some even believe that muddy, grainy shadows are inherent to film, as if the scanner’s automatic adjustments to underexposed negatives are normal or even a unique feature......
 

Saganich

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100% agree.
 
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dcy

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I think I'm about to reveal just how little I know about film, but I was expecting that once I've nailed down the right ISO for the film + developer + paper combo, I could just set that ISO and trust the camera to do the right thing... I understand why I should overexpose a high-contrast scene so there's detail in the shadows, but I don't understand why I'd have to adjust anything for Christmas dinner vs skiing in sunny-16 conditions. Aside from contrast, why can't I just trust the light meter to take care of it?
 

pentaxuser

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Good examples of what you said, Matt , to illustrate them I'd have no way to be able to know which print was from which negative

pentaxuser
 

MattKing

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Assuming your camera and meter are working properly...
In most cases, you can trust the light meter to give you something reasonably close to optimal. And if the negative is close to optimal, the steps that follow - darkroom adjustments or digital post processing - can usually make up for any minor problems.
The outliers become more obvious as you get used to things. Not surprisingly, the scenes that require that the meter reading be varied from are the ones that are far from "average". The much brighter than middle tone ski slopes are a great example - you probably want the negative to give you white snow in your result, not medium grey snow, so if it is mostly white in what you see, you need to change the exposure from the meter recommendation to brighten everything up - i.e. increase the exposure.
The reverse applies to a very predominantly shadowed scene. The meter setting needs to be adjusted to make sure that the shadows look dark in your result, not an average tone. So to make those shadows look dark, you you need to change the exposure from the meter recommendation to darken everything down - i.e. decrease the exposure.
But if there is a wide distribution of tones in the scene, and you want there to be a wide distribution of tones in the result, the meter reading will likely do the job, and any tweaks can be done in the darkroom/post.
Slide film is a bit more exacting in its demands, but generally speaking the same applies. It is just that you may have to make adjustments slightly more frequently, and you are slightly more likely to have some results where you can't solve problems afterwards in post.
There is a fairly high number of regularly participating members here on Photrio who have lots of experience and are therefore likely to make adjustments more frequently than what I'm suggesting in this post, but those adjustments are more in the nature of small refinements than they are necessary changes. Something like a half-stop change in exposure may give you a slightly more optimum negative, but unless and until you have been doing this a fair bit you probably won't really appreciate the difference. So don't worry about that, until you have built the sort of experiential feedback loop that only comes with time and experience. Until then, your negatives will probably turn out fine in most cases if you trust the meter, but make adjustments when the need to do so is obvious and clear.
 
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dcy

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!!!!!!

You just made me realize why my photos from my trip to White Sands were so difficult to scan. This roll was 50% from White Sands and 50% from other trips. Last weekend I was digitally processing that roll and it was so frustrating that I couldn't find settings that would work for most photos. I spent 2.5h editing the roll in batches of similar-looking photos. I blamed the film (it was an Orwo film) and the camera (a PEN from the 1960s).

Now that I see your explanation it makes sense. The light meter likes to make the scene mid-gray. So... it made the beautiful pure-white sand dunes come out yucky grey.



Thanks!

And now I'm in a better position to interpret that experimental feedback.
 

GregY

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A meter is a tool that's designed to do a task. Where you point it and the exposure settings are up to the photographer.....
the concept of 10,000 hrs to mastery isn't wrong....
 

Alex Benjamin

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dcy said:
Aside from contrast, why can't I just trust the light meter to take care of it?
Click to expand...

For the same reason you can't just put the key in the ignition lock and let the car take care of taking you where you want.
 

Bill Burk

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Alex Benjamin said:
For the same reason you can't just put the key in the ignition lock and let the car take care of taking you where you want.
Click to expand...

But you can go all the way up and down a mountain road with a stick shift in third gear if you wanted to.
 

MattKing

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Bill Burk said:
But you can go all the way up and down a mountain road with a stick shift in third gear if you wanted to.
Click to expand...

Maybe you shouldn't.
If going up, you might be likely to stall the engine.
And if going down, you might end up needing to have the brakes looked at!
 

Craig

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dcy said:
Now that I see your explanation it makes sense. The light meter likes to make the scene mid-gray. So... it made the beautiful pure-white sand dunes come out yucky grey.
Click to expand...
The light meter is calibrated to give correct exposure with an average scene reflectance of 18%. That's where the grey cards for metering come from. And most of the time, for most common things, that works great.

However, things like snow or white sand in bright sun might have a reflectance of nearer to 90%, not 18%. The meter doesn't know what the subject is, so it exposes to make the snow middle grey. As Matt says, you have to compensate to get a correct exposure, often adding about 2 stops of exposure over the meter setting. The same concept applies for something black or very dark, but reverse the exposure compensation.
 

koraks

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dcy said:
I could just set that ISO and trust the camera to do the right thing
Click to expand...

Well, see the other responses above; a meter is just a tool and ultimately it cannot be assumed to know what it's looking at. The most basic meters (like the one in your Pen) assume the world is an infinite sheet of flat grey cardboard that's evenly illuminated.

Going out on a limb, your strategy of relying entirely on the meter will work in most cases provided you're using something like a Nikon F5 or F6, or one of the later Nikon DSLR's. The reason is that in those particular cameras, the artificial intelligence the matrix meter is equipped with is so effective that it tends to nail exposures in virtually all cases. But those are really exceptions to the rule, and don't assume that camera's from other brands from the same era will work as well in this department (they don't.)
 

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I think you can do it all digitally but the technique is important.

With a dedicated film scanner it's dynamic range is low and often doesn't match the wider range of the film, which is why best practice for film scanning is to make a low contrast scan without any shadow or highlight clipping which will look awful, but you then rearrange the tones to how they should look, or to your preferred look, in Lightroom or Photoshop and do all your dodging and burning at the same time. The minor advantage a dedicated film scanner has is that the software inverts the image from a negative to a positive in one step.

But 'scanning' with a digital camera and it's much wide dynamic range copies the negative in all it's detail and tonal range, and if that isn't good enough if you copy as a RAW file you can further process the image non-destructively before any Lightroom stage. Inverting the image from negative to positive is done with a software plugin (many are available) for Lightroom or Photoshop. If you are skilled you can invert the image without any extra software. But I don't really see why it's only in a darkroom that some awkward images can be saved.
 

koraks

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250swb said:
With a dedicated film scanner it's dynamic range is low and often doesn't match the wider range of the film
Click to expand...

WRONG. We're discussing negatives here. Dedicated film scanners are made so as to be able to scan a wide range of film, very specifically including color transparencies. The density range of those far surpasses that of B&W (let alone color) negatives. Hence, the dynamic range of a film scanner is very high comparative to the density range of a typical (even overexposed and overdeveloped) B&W negative.

250swb said:
But 'scanning' with a digital camera and it's much wide dynamic range copies the negative in all it's detail and tonal range
Click to expand...
The camera has no user-adjustable hardware gain and thus by default is set to a relatively wide dynamic range (it needs to capture a typical daylight scene after all). Since the gamma of a negative is well below 1, this means that even for a wide-range scene, a negative will only occupy part of the dynamic range of the camera sensor. In practice, this is not really a problem given the relatively clean (noiseless) signal from the camera especially if it's used in RAW format (yielding a bit depth of 12 on 15+ year old cameras or more on modern ones). Moreover, it's doubtful whether a scanner performs much better - and in practice it can be argued to do much worse, since hardware gain may not be available either (instead, software 'gain' is used and simply truncates the available signal depth) and sensor noise performance on typically 20+ year old scanners is likely to be far inferior to that of a modern camera CMOS sensor.

There's a lot of hearsay, misunderstandings and incorrect assumptions underlying amateur scanning practices (and some pro conservation scanning as well). What's particularly frustrating is that these falsehoods keep being rehashed on forums, YouTube channels etc. without being challenged, and thus, people keep making choices that go counter to their aims, and spend countless hours trying to reinvent wheels that have been around in perfectly usable form since about the 1990s.
 

Yezishu

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250swb said:
I think you can do it all digitally but the technique is important.
Click to expand...
Professional film scanners have a much larger dynamic range than needed for negatives, as they were originally designed to extract maximum detail from slides. Some so-called “professional” scanners are actually modified flatbeds, I suspect you might be referring them. Many features in new digital cameras, like pixel shift or multi-exposure or multiple native ISOs or 16/48 bit images, were standard in older film scanners, which didn’t have to account for shutter speed or subject movement.

While modern digital cameras offer impressive dynamic range, practical issues remain—such as aberrations, vignetting, and edge resolution loss caused by shooting through micro lenses. Scanners also use lenses, but only the central portion, minimizing these problems, and is factory-calibrated with color and imaging. Although digital cameras are highly capable, they still requires inspection, comparison, calibration, and post-processing, I wouldn’t say their output is immediately ready for use.

There may be another important reason: these old methods were part of the original film design and have been validated by decades of visual evaluation and acceptance. Even if a digital camera can capture better images, how can we be sure for this? Generally, we must calibrate the camera and workflow based on the widely recognized results from darkroom prints and traditional scanning.
 
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