F stop printing

lenshustle · Sep 17, 2022

The theory isnt holding up very well well dropped to nuts and bolts.

1. the timer used by many, and that book chapter the fellows linked too, is a gralab 300. Officially only does whole seconds and minutes.

Dont see how i can do that ultra reliable and ultra repeatable 8.6 second exposure time.

2. Unless you use grain focusing, I dont see how it can beat a standard 2,4,6,8 etc exposure test.

2. Can the data actually correlate between different enlarging lenses?

light meter data in camera doesnt give the same shutter and aperture settings when i swap out my 75mm lens that liked f5@1/150, and put in my 75-200 focal length lens and set it to 75mm and f5.. different diameter. 75mm lens is 55mm thread and 75-200 is 63mm.

SO i dont honestly see the theory of creating a complicated f stop guide for length of exposure holding water when i do the initial base test with my 50mm enlarger lens, and then need to swap in my 90mm enlarger lens so i can do an 11x14 print.
YES i know in the real world of non f stop printing you would do a new test strip, however the claimed benefit of f stop printing is supposed to be built in abilty to simply multiply the f stop number by a magic number to give you the correct setting for the larger size print you want to make.

awty · Sep 17, 2022

I don't understand your logic, I've always used f-stops, first by chart, then I bought a f-stop timer. Is the only way to do accurate dodge and burns and account for dry down etc.
I always do a test strip when changing paper no matter what.

Mick Fagan · Sep 17, 2022

1. Unless you supply the link, I have no idea what or where it is. That said, the Gralab timer is alright, but for F-Stop printing you really need a timer that has tenths of a second. Which is what I have.

2. Grain focusing has nothing to do with exposure times, focusing is important to ensure you aren't getting flare with an out of focus negative, critical focusing with a grain focuser is very helpful in ensuring you get the best possible print.

Once you understand the difference in either whole stops, half stops or even quarter stops on a test print series, you will then understand how much easier it is to ascertain the correct print exposure for your requirements. Once the penny drops, you will probably never entertain a 2, 4, 6, 8 second set of test exposure steps again.

3. (second 2 on your list) Not really but within reason it will work.

As to your different camera lenses having different filter sizes and different focal lengths, f/5.6 should be f/5.6 on both lenses as this is a calculation of the aperture and focal length. If you really get into the nuts and bolts of your two lenses, you may find that your prime 75mm camera lens is possibly somewhere between 73mm to 77mm in focal length. Actual focal length is rarely what is marked on the lens barrel. Same goes for your other lens.

I'm at a bit of a loss as to why you would do test prints with a 50mm lens then swap to a 90mm lens for a final print; are you using two enlargers or is there some other reason?

By the way, welcome to the forum.

BMbikerider · Sep 17, 2022

I have used it occasionally but do not have one of the automated timers. I have the analogue figures for the different stops and have manually worked out how much difference there is between each 1/4 stop. It works for me so why should it not work for the original poster?

Yes I use a grain focussing device (Peak) but there again I use it for all my printing B&W or colour and does not have any effect on the exposure. Just where do you get that idea from?

xkaes · Sep 17, 2022

Dealing with TENTHs of a second enlargement exposures is a fool's errand -- whether for test exposures or actual prints.

In that situation, sensible solutions are reducing the light to extend the exposure times into something manageable -- such as stopping down, using ND filters, reducing the wattage of the bulb, etc.

faberryman · Sep 17, 2022

awty said:
I don't understand your logic, I've always used f-stops, first by chart, then I bought a f-stop timer. Is the only way to do accurate dodge and burns and account for dry down etc.

I am not sure what you mean by accurate. Using time has always worked well for me. If I determine that an area of the print needs to be burned in for 13 seconds, 13 seconds seems pretty accurate. How would f-stop printing be more accurate than 13 seconds?

Nicholas Lindan · Sep 17, 2022

faberryman said:
I am not sure what you mean by accurate. Using time has always worked well for me. If I determine that an area of the print needs to be burned in for 13 seconds, 13 seconds seems pretty accurate. How would f-stop printing be more accurate than 13 seconds?

f-Stop printing isn't more accurate for dodge & burn - it is more convenient. A 0.5 stop burn stays at 0.5 stop as you change print sizes, and in many cases as you change papers and the base exposure has to change because the paper speed is different. An f-Stop timer reduces fumbling with times and makes printing more convenient, that's all.

Counting 'elephants', a metronome, a GraLab, a digital timer or an f-Stop timer can all produce identical lovely prints.

Everybody proselytizes for their preferred method. I'm no exception - "Get thee an f-Stop timer and thou shalt be saved!"

Vaughn · Sep 17, 2022

I've tried to wrap my mind around f-stop printing. I just see no advantage with the way I printed silver gelatin prints.

I don't change print sizes...or extremely rarely. My burning is done in a way that negates any advantage of that system. I made a test strip, a test print, then I was off to the races.

ic-racer · Sep 17, 2022

2, 1.4, 1.26, 1.19 and a calculator....

Dali · Sep 17, 2022

What a mix... Good luck to sort it out.

Pieter12 · Sep 17, 2022

xkaes said:
Dealing with TENTHs of a second enlargement exposures is a fool's errand -- whether for test exposures or actual prints.

In that situation, sensible solutions are reducing the light to extend the exposure times into something manageable -- such as stopping down, using ND filters, reducing the wattage of the bulb, etc.

Those tenths add up as you multiply them for f-stop timing.

Pieter12 · Sep 17, 2022

To the OP: get yourself to a photo class. You seem to be confused about how photography works. If any given f-stop was not equivalent across all taking lenses, despite actual opening sizes, then hand-held exposure meters wouldn't work.

Jay Schrotenboer · Sep 17, 2022

lenshustle said:
on my aperture comment, aperture on a photo lens is a fixed ratio. diameter of the physical opening and the focal length of the lens. But it is not consistent between lenses.

meaning while i held my canon len shutter open, annoying process, and held it up to a different lens with longer focal length and larger diameter, the apertures both set to f/8, the actual openings when fully open were not the same.

When i tried the photo group thing, i got to do the same trick with someones TLR camera they brought in. They swore up and down that the aperture size was the same no matter what, but when i proved them that the aperture opening on their TLR with bay one lens mount when set to f/3 was larger then the opening on a fd mount 55mm threaded nifty 50 when set to 1.8 they got upset.

I am going to attempt to explain this as best I can, but also I am going to definitely recommend you take a class or find a book for beginners in photography as this should help you understand some of these basic principles. The f stops on a camera lens are a simple mathematical equation (f/x) where f=focal length of the lens, and x=the divisor that expresses your f stop. Let’s take an example, f/2.8, that should be common on the lenses you have mentioned. If you have both a 80mm and 50mm lens set to f/2.8 you just need to do the math to find the physical openings, so that looks like this 80/2.8=28.57mm 50/2.8=17.86. The physical openings are different, but because the light has to travel further to the focal plane on the 80mm than for the 50mm the amount of time to get the same exposure is identical. One problem you might also be experiencing is that it would be impossible to actually measure this opening with the lens assembled as the glass will distort what you are seeing and you would need to disassemble the lens and measure at the actual Aperture (something I would definitely NOT recommend doing). I do hope this is at least somewhat helpful, but do start educating yourself on photography and a lot more will make sense to you.

Vaughn · Sep 17, 2022

lenshustle said:
...

When i tried the photo group thing, i got to do the same trick with someones TLR camera they brought in. They swore up and down that the aperture size was the same no matter what, but when i proved them that the aperture opening on their TLR with bay one lens mount when set to f/3 was larger then the opening on a fd mount 55mm threaded nifty 50 when set to 1.8 they got upset.

Lens diameter has no affect on f-stop (not part of the equation determining f-stop), except a larger diameter lens might be able to achieve a larger aperture.

MattKing · Sep 17, 2022

+1 to Nicholas' post.
If you want to see why f-stop printing works well, just do two test strips:
1) the first with exposure times of 4, 8, 12, 16, 20, 24 seconds; and
2) the second with exposure times of 4, 5.6 (if you can), 8, 11, 22, 32 seconds.
If a correct exposure is somewhere in the middle of those times, you will most likely observe how much easier it is to evaluate the differences in the test strips - the second provides a much more regular progression of densities. In this case, at 1/2 stop intervals.
If you are working with a Gralab 300 (which is really more appropriate as a process timer than an enlarging timer) your ability to easily make use of the full flexibility of f-stop printing is limited - 1/6 stops are just too hard to use it with - but the logarithmic or geometric approach to exposure control still is much closer to how the materials and our eyes work than other approaches.

Vaughn · Sep 17, 2022

Still does not make a lot of sense for me to use it. My f stop was chosen to give me exposure times around 20 seconds. Running a test strip at 15, 20 and 25 seconds gave me all the info I needed to determining the exposure of my test print. Easy enough to see where the "proper" exposure falls between two exposures only 5 seconds apart when you are in the 20 second range.

Others working in different manners might benefit greatly from the f-stop method. Others, not.

Why run a test strip from 2 to 24(32) seconds if one has a decent amount of printing experience.? TMI.

MattKing · Sep 17, 2022

Vaughn said:
if one has a decent amount of printing experience.

The OP lacks that.
The demonstration I suggested was intended to both provide a clear visual demonstration for someone who isn't all that familiar with what one should look for, and to assist if one is working in temporary or changing darkrooms.
If you are blessed with a permanent darkroom and are able to work in consistent conditions, a strip with 1/3 f-stop increments centred around a likely exposure time makes more sense.

Vaughn · Sep 17, 2022

We taught the old style to beginners for decades. Works just as well, differently, I agree, but really no better, and certainly no worse.

A test strip to get close, another, if needed, to get very close (allows one to change contrast levels for the second test strip), and a beginner is good to go.

In reality, beginners will have far more difficulty in determining what what a good print looks like than the how to make the test strip itself.

faberryman · Sep 17, 2022

MattKing said:
...2) the second with exposure times of 4, 5.6 (if you can), 8, 11, 22, 32 seconds.

So let's say you inspect your test strip and determine that proper exposure is between 22 and 32 seconds. For your next test strip, do you calculate the fractional f-stops between 22 and 32 to arrive at your exposure intervals? Or do you just expose between 22 and 32 in 2 sec intervals? Seems like the latter choice wouldn't make your brain hurt as much.

Pieter12 · Sep 17, 2022

Vaughn said:
We taught the old style to beginners for decades. Works just as well, differently, I agree, but really no better, and certainly no worse.

A test strip to get close, another, if needed, to get very close (allows one to change contrast levels for the second test strip), and a beginner is good to go.

In reality, beginners will have far more difficulty in determining what what a good print looks like than the how to make the test strip itself.

I'll second that. Learn how to judge and make a good print. Then take on f-stop printing. And if the OP can't afford books, there is always the public library.

I am a little taken back by the OP's approach. With little knowledge of photography, it seems he obviously spent some money putting together a darkroom, even if all the equipment was donated. But he can't afford books. He's going to probably end up spending more on paper and chemistry to learn printing. Photography is not an inexpensive field.

gone · Sep 17, 2022

Vaughn said:
We taught the old style to beginners for decades. Works just as well, differently, I agree, but really no better, and certainly no worse.

A test strip to get close, another, if needed, to get very close (allows one to change contrast levels for the second test strip), and a beginner is good to go.

In reality, beginners will have far more difficulty in determining what what a good print looks like than the how to make the test strip itself.

That's what I think too. We tend to over-think things like this, focusing (forgive the pun) on procedures instead of just looking at the print. It just means getting the best print through trial and error w/ a test strip/test print protocol.

Sure, that can be done in a lot of different ways and manners, but it always comes down to looking at the print and going where it tells you it needs to go, and then deciding where you wish it to go.

Pieter12 · Sep 17, 2022

faberryman said:
So let's say you inspect your test strip and determine that proper exposure is between 22 and 32 seconds. For your next test strip, do you calculate the fractional f-stops between 22 and 32 to arrive at your exposure intervals? Or do you just expose between 22 and 32 in 2 sec intervals?

When you use f-stop printing, you don't deal in seconds, but in f-stops. The strips are whatever f-stop increment apart the you decide when making it. So if you determine the proper exposure is between two strips, it is between two stops or fractions of a stop. You would then set an f-stop timer to that increment, similarly to how you would adjust for a camera. If you don't have an f-stop timer, you would use a chart or calculator to determine that time in seconds.

faberryman · Sep 17, 2022

Pieter12 said:
When you use f-stop printing, you don't deal in seconds, but in f-stops. The strips are whatever f-stop increment apart the you decide when making it. So if you determine the proper exposure is between two strips, it is between two stops or fractions of a stop. You would then set an f-stop timer to that increment, similarly to how you would adjust for a camera. If you don't have an f-stop timer, you would use a chart or calculator to determine that time in seconds.

So in my example, the f-stop timer (interesting it is called a f-stop timer instead of an f-stop f-stopper) automatically calculates the fractional stop interval say for four intervals between 22 and 32?

Pieter12 · Sep 17, 2022

faberryman said:
So in my example, the f-stop timer (interesting it is called a f-stop timer instead of an f-stop f-stopper) automatically calculates the fractional stop interval say for four intervals between 22 and 32?

At least with the RH designs f-stop timer, the only time you really work with seconds is when you set the initial test strip time and when you make a record of the final exposure to be able to repeat the print at a later date. To make a treat strip, you set a minimum time to start with, say 5 seconds. Then you set the f-stop increment you want to work with, say 1/3 stop. In test-strip mode, the timer automatically repeats this increment based on the initial time. The other thing is you make a test strip by covering the print more each time rather than uncovering as a traditional test.

The difference is in what you see on the test strip. With a traditional test strip, the difference between bands is whatever interval you have set your timer to. Say 5 seconds. So the last band is 5 seconds, the next 10 seconds, then 15, 20 and so on. The f-stop test strip bands are whatever f-stop interval apart that you set the timer to. So the first band is 5 seconds, the next +1/3 stop, the next +2/3 stop, a full stop, 1 1/3 stops, etc. The intervals are regular, unlike the traditional test strip and easier to judge or get closed to the final exposure.

As an example, if you were to make an f-stop test strip with no negative in the carrier, you would end up with an evenly spaced gray scale.

Nicholas Lindan · Sep 17, 2022

faberryman said:
So in my example, the f-stop timer (interesting it is called a f-stop timer instead of an f-stop f-stopper) automatically calculates the fractional stop interval say for four intervals between 22 and 32?

Yes - except with an f-Stop timer you don't work in seconds but stops of time.*

With an f-Stop timer you would have a base exposure of 4.5 stops (22 seconds) and a step increment of 0.1 stops. In this example your first test strip would be from, say, 3.0 stops (8 seconds) in 0.5 stop increments - if you did a 5 step strip that would have given you exposures of 3.0, 3.5, 4.0, 4.5, 5.0 stops, or 8, 11, 16, 22, 32 seconds.

If you do test strips by covering up a bit of paper then the exposures needed would be 8, 3, 5, 6, 10 - an f-stop timer does all that for you.

It is plain to see why a linear sequence is 'easier' with a seconds-only timer: 8 seconds and then 6 exposures of 4 seconds till you get to 32.

If you use the f-stop method it gets easier to eyeball a print - "Oh, yeah. Need to burn that in 0.5 stops" and you don't have to think farther than that. BTW, paper is contrastier than film: a 0.5 stop change in print exposure is equivalent to 1 zone (stop) change in film exposure.

We take pictures in stops - we don't think in terms of entrance pupil diameter of the lens (which is what we are directly controlling) or the number of milliseconds of shutter opening - so why not just carry stops over into the darkroom? I can just see a linear shutter speed dial: 1 second, 0.999 seconds, 0.998 seconds ... turn, turn, turn ... 0.002 seconds, 0.001 seconds - lots of precision in exposure around 1 second but at the other end it jumps from 1/500 to 1/1000 of a second.

--

* RH timers are hybrid seconds-stops timers, much like the original Nocon timer. The base exposure time is in seconds which is then adjusted up and down in fractions (1/2, 1/3, 1/4 ... 1/24(?)) of a stop. Burns and test strips are in fractions of a stop over a base exposure.

Darkroom Automation timers work entirely in decimal stops of time and only use seconds to count down an exposure.

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