Determining darkroom exposure times from scanned negatives

[thanos]

Hello, everyone.
My first post here.

Well the title is not entirely correct, as I don't scan the negs just read the density ranges with Vuescan.

After about 10 years of digital photography I'm starting to regain interest on the darkroom esp. for hand tinted fiber prints.

I've read all the "scanner as densitometer" threads here and at APUG but I can't find a reply to my question.

Till now I've been making test strips to determine the correct exposure time and filter grade (I'm using ILFORD MGIV FB developed in MULTIGRADE DEVELOPER). I think I'm good at judging a contact print and then with a waste of 2-3 papers I get a workable print that can be further tuned. I take notes for everything and review them occasionally. I know I can use the min time / max black method to get drugstore prints but still the paper waste is big for my available budget.

I wish I could cut down on the paper waste and the darkroom hours, so just this week I got Vuescan and I'll try to read the film densities on scanned strips. So, I cut the film in strips of 5 frames and I preview each one in Viewscan. With Ctrl pressed I read the densities and take notes of the density range. Then using the Ilford published chart I determine the needed grade. I don't scan the film. I just use Vuescan as a densitometer.
It's easier for me to use the computer and my old Scanjet at home than go to the local club darkroom and spend hours there (don't ask - family reasons).

But, I want to have some way to get the enlarger exposure time in the ballpark at the first try if possible. Is it possible to do this by means of the film densities reading? Are there any published charts that can help?

Reading various threads over at APUG I get the impression that I need to do more paper strips for the exposure time. Is this correct, or is there some other faster/more efficient way?

Thanks,
Thanos

[Loris Medici]

I'd suggest that you learn something about "split grade printing". (If you already don't know something about it, that is...) With this system, you can find the correct exposure time(s) and be able to print for desired contrast (with much more dudge/burn control compared to single grade printing - because you can do it independently for shadows and highlights!) by doing only 2-3 test prints.

That's for "drugstore prints" (in your terms), a "fine print" takes much more struggle / effort, and if you're after making fine prints you should forget about the shortcuts and/or cost of test papers! You may just return back to digital printing and do all the necessary adjustments on-screen - which seems like this is what you're actually looking for, but in the wrong place... (= Darkroom printing.)

Regards,
Loris.

[thanos]

Hi, Loris.
Yes, I do know about the split grade technique although I haven't used it yet. Actually, I'm not interested on digital printing. I just want to use the computer to help me in the darkroom in a way that ohter people use other automated means (like a densitometer) for the wet prints. Also, I want to minimize the hours spent in the darkroom and as a side effect minimize the wasted paper cost (that is quite important to me given the economic times we live in).
Finally I'm more and more inclined to believe that I can't avoid doing the test strips even when knowing the density readings.

Regards,
Thanos

[Loris Medici]

...
Finally I'm more and more inclined to believe that I can't avoid doing the test strips even when knowing the density readings.
...

Yep.

In any case a computer scan and on-screen image manipulation still helps much in darkroom printing. I was evaluating / analyzing the negatives that way, back when I was printing in the darkroom; I already knew what I have to do in the darkroom to print the negative the way I want, before getting in there. As a result, test paper cost + testing time was considerably decreased...

[bob carnie]

Over the years , I have concluded test strips are a waste of time.

Basically I am now into full sheet test, and watching emergence in the developer for clues to contrast and density in-balances.

You can learn alot about a final print by using this method and since the days of lith printing where all you do is watch for pull time , keeping track of emergence in developer has proven for me at least to be the way to evaluate prints.
Before you turn on the lights , most dodge/burn combinations should be apparent.


Before I would wait for the lights, look at each test strip of a small area and then make another... Complete waste of time.

Take this further and one should evaluate visually on the lightbox, then on the easel and contrast grade and basic density should become apparent over time and practice.

I will say that after 6 years of intensive PS training , I feel more comfortable printing with an enlarger, I use a modified split printing method which IMO is totally in tune with Curve Shaping in PS.

[thanos]

Take this further and one should evaluate visually on the lightbox, then on the easel and contrast grade and basic density should become apparent over time and practice.

Hi Bob and thanks for the reply. I'm considering the lightbox evaluation too. As a means of faster evaluation, I'm about to produce, for each way of film development (pushed, pulled etc), a set of test frames photographing a step chart and keeping notes of the measured densities. Then I hope instead of scanning i'll visually compare the step charts to my real frames and estimate the density range from this. That way I hope I'll even get rid of the scanning preview and be even faster in the darkroom. I do understand that dodging and burning doesn't need so much extensive measurements but it's more a matter of taste.

How does that sound for efficiency?

[Don Bryant]

How does that sound for efficiency?

Thanos,

You need to spend time printing your negatives and learning how to evaluate them visually on a lightbox or simply hold the negative up to a light source.

By practice you will learn to quickly hone in on the preferred (note I did not say correct) paper contrast and printing time or close to it.

If you wish to save paper use 1 or 2 inch wide strips cut the length of the paper to do test exposures and contrast tests.

Scanning negatives and making home made step tablets really is a waste of time IMO. Vuescan used as a transmission densitometer has it's limitations and densities above about log 2.0 aren't very accurate. You can test this by measuring a calibrated step wedge.

Just go into the darkroom and try to print as frequently as possible. If you can print daily you will become quite efficient quickly.

Good luck,

Don Bryant

[bob carnie]

let your onboard densitometer, which is located behind the left ear become your guide..

After time with lots of prints under your belt you get pretty good at evaluating negatives and starting times.

Thanos,

You need to spend time printing your negatives and learning how to evaluate them visually on a lightbox or simply hold the negative up to a light source.

By practice you will learn to quickly hone in on the preferred (note I did not say correct) paper contrast and printing time or close to it.

If you wish to save paper use 1 or 2 inch wide strips cut the length of the paper to do test exposures and contrast tests.

Scanning negatives and making home made step tablets really is a waste of time IMO. Vuescan used as a transmission densitometer has it's limitations and densities above about log 2.0 aren't very accurate. You can test this by measuring a calibrated step wedge.

Just go into the darkroom and try to print as frequently as possible. If you can print daily you will become quite efficient quickly.

Good luck,

Don Bryant

[pschwart]

Learning to evaluate negatives via lightbox and test strips (test prints) comes with experience. You might consider getting an enlarging meter. I have never used one of these so I can't offer any advice.
http://www.darkroomautomation.com/da-main.htm

[thanos]

By practice you will learn to quickly hone in on the preferred (note I did not say correct) paper contrast and printing time or close to it.

Hi Don and thanks for the tips. I know there's no shortcut for darkroom experience.

Vuescan ... densities above about log 2.0 aren't very accurate.

Didn't know that. But I hope it's still more accurate than eyeballing?