Determining contrast for enlargement

[redbandit]

Yes, i "know" the contrast of the enlargement is determined by the contrast of the negative, but the thing is the books i have do not go into detail on defining contrast.

for them high contrast is "negative is all white or black, no mid tones". Low contrast is "mainly just mid tones"

 

[MattKing]

There are some important and comprehensive definitions that answer your question, while involving things like taking densitometer measurements and graphing results.
But I don't think that is what you are looking for.
I consider that contrast is a measure of how similar adjacent tones appear in relation to each other. With my definition, you can have an image with both high contrast and "mainly just mid tones".
Others tend to think of contrast as being a measure of the difference between the darkest and lightest areas of the image that contain observable detail.
I find this link to be useful when talking about assessing negatives, but the analysis seems useful in response to your question: https://www.ephotozine.com/article/assessing-negatives-4682
In any event, what constitutes good contrast will be dependent on your image and the materials you are working with.

 

[albada]

Do you want a precise definition of contrast, or a procedure for deciding what grade to print at?

Defining contrast well is an interesting subject, and part of it is addressed in this thread. In that thread, I had a better idea, and @Stephen Benskin explained some things and provided some reference material showing that my better idea was a worse idea. But a crucial concept through that thread is that of "exposure range", which is the amount of exposure needed to go from a specific low density to a specific high density. This applies to both negatives and prints, and the two exposure ranges should somewhat match. It's called LER because it's the log of exposure range.

Given a negative, a common procedure in the darkroom is:

1. Guess the grade, and make a test-strip to obtain correct exposure for the highlights.
2. Change grade so that shadows appear as you want them (more test strips).

 

[redbandit]

Do you want a precise definition of contrast, or a procedure for deciding what grade to print at?

Defining contrast well is an interesting subject, and part of it is addressed in this thread. In that thread, I had a better idea, and @Stephen Benskin explained some things and provided some reference material showing that my better idea was a worse idea. But a crucial concept through that thread is that of "exposure range", which is the amount of exposure needed to go from a specific low density to a specific high density. This applies to both negatives and prints, and the two exposure ranges should somewhat match. It's called LER because it's the log of exposure range.

Given a negative, a common procedure in the darkroom is:

1. Guess the grade, and make a test-strip to obtain correct exposure for the highlights.
2. Change grade so that shadows appear as you want them (more test strips).

pulling out a slide rule and hunting down data sheets for each piece of film i have and doing calculations is not my thing.

And just randomly guessing at grade is really killing the paper budget, even just using the cheapest 5x7 it is getting expensive. Sure i just went 8 months without using my enlarger, i actually forgot where the power button was on my head, but im trying.

i HAVE thought one of those density meters would be nice to try but i just dont want to drop that much cash on something without KNOWING it will do what i need.

 

[MattKing]

Are you working with variable contrast paper?
Have you considered doing a contrast "ring-a-round"?

 

[otto.f]

With my definition, you can have an image with both high contrast and "mainly just mid tones".

I would appreciate an image as an example of that

 

[redbandit]

variable contrast only.


i had to stop working with my enlarger for to long, and am paying the hit in the wallet on paper.

 

[koraks]

And just randomly guessing at grade is really killing the paper budget, even just using the cheapest 5x7 it is getting expensive.

Use smaller test strips.

i HAVE thought one of those density meters would be nice to try but i just dont want to drop that much cash on something without KNOWING it will do what i need.

See if someone in your area has one so you can try it out / see it used in action before committing.
Of course a densitometer will help you get the information you need, but since you're not too fond of going over datasheets and charts, my guess is it's not going to be of much use to you. It's a bit of a theoretical approach, not so much a hands-on one.

Look, it's either going to be a theory-based approach where you substitute the trial-and-error of using test strips/prints (to an extent) with measurements and theory, or it's going to be the manual labor of trial & error and the consumables expenses that go with it. The only alternative beside that is to just dial in some random contrast and don't worry about how the print might have been better at a different grade or with some burning & dodging etc. Mind you, nothing wrong with that; I actually do that a lot as a substitute for making contact sheets.

 

[bernard_L]

i HAVE thought one of those density meters would be nice to try but i just dont want to drop that much cash on something without KNOWING it will do what i need.

Money and electronics won't buy you good prints. The idea behind that approach is to determine exposure and contrast such that spot "X" of the negative will print just maximum black (or 90% of Dmax, or whatever), and, likewise, that spot "Y of the negative will print just shy of pure white (or D=0.1, or whatever). (even to match mid-tones with a reflection gray scale...) That approach fails for the following reasons:

• How do you choose spots "X" and "Y" on the negative? A specular reflection that subjectively is beyond white? a keyhole into a dark room that is subjectively beyond pitch black? Of course, I'm exaggerating, but that is to convey the idea.
• How to choose the reproduction tones "or whatever" in the above? For light tones, as you push towards paper white there comes a point where you actually lose brilliance, because the tone reproduction curve rolls over at the shoulder; wehn is "just right"? And some shadow tones (in some images) can be safely dropped into maximum black.
• The reproduction of mid-tones plays an important part in the feeling conveyed by a print, IMO as much as the placement of the highlights and shadows.

Wrapping up, and IMHO: an electronic device may help you determine a good approximation of the contrast and exposure, and to cut down on initial steps of trial and error. Experience and a good eye can achieve the same (not that I'm there yet). Then dedicated test strips in critical regions of highlights, mid-tones, and shadows. Then a full-frame test print, that will reveal global relations between the tones, that the test strips could not. Then...

A contact sheet may also be useful, not just to select "interesting" frames, but to transfer exposure (grade-fstop-time) information, gained through hard work from one fame to another. Hhmmm frame 3 prints lighter than frame 2 on the contact sheet, so I'll need to expose longer (other things equal...); ditto for paper grade.

 

[awty]

I use trial and error using tests strips, comparing from when high light detail comes in and where blacks come in. The more you do the better you can get it right with less test strips, but not using test strips I end up having to start again a waste more paper.
Want to be a better printer, get a bigger bin, there's no escaping wasting paper.

 

[albada]

Look, it's either going to be a theory-based approach where you substitute the trial-and-error of using test strips/prints (to an extent) with measurements and theory, or it's going to be the manual labor of trial & error and the consumables expenses that go with it.

There is a third approach: Use a controller that works with an easel meter. RH Designs makes one, and @dkonigs is designing a more modern one. Both show where the points you measured fall on the density scale, letting you adjust exposure and grade until those points have the tones you want. I made a DIY controller that works the opposite way: You tell it the tones you want for two points you measured, and it'll set exposure and grade to obtain those tones. Both kinds of controllers can also tell you how much to dodge/burn. With either type of controller, after some practice in selecting important points to measure, most prints look fine on the first try, thus wasting little paper.

 

[koraks]

Use a controller that works with an easel meter.

That's a theory-based approach which is relatively heavy on the investment side as well as on the theoretical side. Trying to use one without being aware of how curves work etc. will be a disappointing experience, regardless of how nicely engineered the device is and how (relatively) user-friendly it has been made.

 

[RalphLambrecht]

Guess the grade, and make a test-strip to obtain correct exposure for the highlights.

1. Change grade so that shadows appear as you want them (more test strips).

 

[RalphLambrecht]

That's really all that there is to it! wonderful explanation!

 

[otto.f]

Money and electronics won't buy you good prints. The idea behind that approach is to determine exposure and contrast such that spot "X" of the negative will print just maximum black (or 90% of Dmax, or whatever), and, likewise, that spot "Y of the negative will print just shy of pure white (or D=0.1, or whatever). (even to match mid-tones with a reflection gray scale...) That approach fails for the following reasons:

• How do you choose spots "X" and "Y" on the negative? A specular reflection that subjectively is beyond white? a keyhole into a dark room that is subjectively beyond pitch black? Of course, I'm exaggerating, but that is to convey the idea.
• How to choose the reproduction tones "or whatever" in the above? For light tones, as you push towards paper white there comes a point where you actually lose brilliance, because the tone reproduction curve rolls over at the shoulder; wehn is "just right"? And some shadow tones (in some images) can be safely dropped into maximum black.
• The reproduction of mid-tones plays an important part in the feeling conveyed by a print, IMO as much as the placement of the highlights and shadows.

Wrapping up, and IMHO: an electronic device may help you determine a good approximation of the contrast and exposure, and to cut down on initial steps of trial and error. Experience and a good eye can achieve the same (not that I'm there yet). Then dedicated test strips in critical regions of highlights, mid-tones, and shadows. Then a full-frame test print, that will reveal global relations between the tones, that the test strips could not. Then...

A contact sheet may also be useful, not just to select "interesting" frames, but to transfer exposure (grade-fstop-time) information, gained through hard work from one fame to another. Hhmmm frame 3 prints lighter than frame 2 on the contact sheet, so I'll need to expose longer (other things equal...); ditto for paper grade.

Thanks being so clear about this, gives me a better feeling (than just irritation) of what I get from the Heiland splitgrade figures and what I see is necessary for an image. The machine can indeed not decide, but you can trick him by measuring some parts and others not to come closer to the image in your mind.

 

[gone]

DON'T read books. Make the prints and look at them w/ your own two eyes. You'll quickly understand this, it's truly a visual thing.

Think of it as cooking. You can read cookbooks until your eyeballs fall out, but the minute you put something on the stove and taste it, ah, then you know.

 

[GregY]

" Make the prints and look at them w/ your own two eyes. You'll quickly understand this, it's truly a visual thing.

Think of it as cooking. You can read cookbooks until your eyeballs fall out, but the minute you put something on the stove and taste it, ah, then you know."

! Exactly

 

[redbandit]

some days, some frames, things seem to fall in place and the first guess on the test strip works for the timer setting. Other days its way off.

 

[redbandit]

and as someone still trying to figure out the contrast difference between 1,2,3,4,5, and then tossing in the HALF grads... having an idea to figure out how it would improve a frame with each one is a killer

 

[redbandit]

"DON'T read books. Make the prints and look at them w/ your own two eyes. You'll quickly understand this, it's truly a visual thing.

Think of it as cooking. You can read cookbooks until your eyeballs fall out, but the minute you put something on the stove and taste it, ah, then you know."

! Exactly

I know, killing paper will help long term but the thing is im doing this on my own. I even tried looking up meetup photo groups, no one does enlarging, none of them do film, and most of them only buy a camera to show it off.

SO all i have is the internet and books. But i do agree, the books arent always correct on things. And i have yet to find a book that can explain why the image is flipped by the enlarging lens.

 

[GregY]

Actually, besides the arcane trio by Ansel Adams, Ralph Lambrecht's. "Way Beyond Monochrome" and Bruce Barnbaum's "Art of Photography" are incredibly practical. But like playing a musical instrument, hands-on time in the darkroom is the way to go.....your prints will get better & better.

 

[MattKing]

I would appreciate an image as an example of that

Most high key images are this way.
I was going to share an example, but I hardly ever take high key images and, it seems, I don't digitize them when I do.

 

[Paul Howell]

I think contrast is subjective, some like to print high contrast, other middle to lower contrast. A good book is a starting point. I have negatives that span 55 years, differnt films were optimized to print grade 2 on papers that no longer exist, printing a contrast ring around, say 4X6 or 5X7 of a negative that you printed in the past with good results and use as a reference, then as others have advised print small test strips. Other possibility is fine hone split grade printing.

 

[GregY]

"Other possibility is fine hone split grade printing."
Another is to 'fine hone' using your VC or color-head enlarger.....

 

[bernard_L]

And i have yet to find a book that can explain why the image is flipped by the enlarging lens.

Picture a ray of light going through the negative, then through the center of the enlarging lens. You are standing in front of your enlarger. If the ray of light has crossed the back of the negative, as it goes down on its inclined path, it moves to the front. Same for left-right.

[why did I choose "through center of lens"? after all the enlarger is not a pinhole camera... that is just to simplify the explanation; in paraxial optics and for a thin lens, a ray through the center goes on a straight path]