Changing aperture during a session

Fatih Ayoglu · Mar 1, 2024

Hi,

When I print BW, I use split grade printing, usually start with 0, or full yellow, establish highlights and mid tones and then move to hard 5, full magenta, to establish shadows. Obviously the paper responds to yellow light much slower than the magenta light, what I mean is, when I need to get like 32s with yellow light, I might be needing only 4 to 8s with magenta light at the optimum aperture of the lens. That makes the dodging/burning really difficult and was wondering if I could move to a different aperture for grade 5, to increase that time a stop or 2.

Cheers,
Fatih

koraks · Mar 1, 2024

Sure. As long as everything remains in good focus, there's no problem.

Don_ih · Mar 1, 2024

I would be concerned the lens will move a tiny amount if I did that - but it depends on the enlarger.

Pieter12 · Mar 1, 2024

Echoing Koraks, I wonder if the focus would shift if it is more than a stop. Also, if you are using a 32 second exposure for the 0 filter and then only 4 seconds for the 5 filter, how much is the 5 even affecting the print? And to correct you, the paper responds more to the yellow/0 exposure than to the magenta/5.

Fatih Ayoglu · Mar 1, 2024

Pieter12 said:
Echoing Koraks, I wonder if the focus would shift if it is more than a stop. Also, if you are using a 32 second exposure for the 0 filter and then only 4 seconds for the 5 filter, how much is the 5 even affecting the print? And to correct you, the paper responds more to the yellow/0 exposure than to the magenta/5.
View attachment 364311

Sometimes what happens is, if I pass minimum required time, grade 5 starts to affect mid tones which I’m trying to dodge and with such durations it might be difficult.

Yes it does respond more, what I’ve meant was it takes more time to burn highlight/midtones than burning the shadows with grade 5. As they say if I’m not wrong, establish highligh t density with time and shadow density with grade.

Fatih Ayoglu · Mar 1, 2024

Pieter12 said:
Echoing Koraks, I wonder if the focus would shift if it is more than a stop. Also, if you are using a 32 second exposure for the 0 filter and then only 4 seconds for the 5 filter, how much is the 5 even affecting the print? And to correct you, the paper responds more to the yellow/0 exposure than to the magenta/5.
View attachment 364311

The reason I’ve asked this was mainly, the sharpness of the grain determines the overall sharpness of the print, and if focus shifts or anything else, obviously grain being printed with grade 5 more, was wondering if the overall sharpness would drop?

koraks · Mar 1, 2024

I expect you might lose a tiny fraction of sharpness due to a variety of factors; focus shift, mechanical disturbance/misalignment, DoF issues etc. But I doubt the overall effect is necessarily problematic if you're careful. I'd just give it a go and see what happens.

pbromaghin · Mar 1, 2024

Heck, just refocus and make a small test strip.

Fatih Ayoglu · Mar 1, 2024

pbromaghin said:
Heck, just refocus and make a small test strip.

How can I refocus when the paper is already there and exposed with grade 0. If I move the paper, most certainly I won’t be able to put it back to the exact same spot.

Don_ih · Mar 1, 2024

Get a very defined negative (something with very sharp lines) and do a test. Determine the proper exposure time for f8 (A). Then expose a piece of paper at f8 for 2/3 A, adjust the aperture to f16, and expose for about twice A. That should show whether or not the definition gets ruined by the adjustment.

pbromaghin · Mar 1, 2024

Fatih Ayoglu said:
How can I refocus when the paper is already there and exposed with grade 0. If I move the paper, most certainly I won’t be able to put it back to the exact same spot.

Never mind. I missed the split grade part.

Fatih Ayoglu · Mar 1, 2024

pbromaghin said:
Never mind. I missed the split grade part.

And I was really hoping you’ll tell me a trick that I didn’t know

Fatih Ayoglu · Mar 1, 2024

Don_ih said:
Get a very defined negative (something with very sharp lines) and do a test. Determine the proper exposure time for f8 (A). Then expose a piece of paper at f8 for 2/3 A, adjust the aperture to f16, and expose for about twice A. That should show whether or not the definition gets ruined by the adjustment.

Good plan

Maris · Mar 1, 2024

In the interests of pessimism, paranoia, and precision I always set the aperture on my enlarging lenses from the same direction. For example f11 is set by moving one click up from f8 never by moving one click down from f16. Aperture iris mechanisms can wear and exhibit hysteresis and click stops may become "soft".

awty · Mar 1, 2024

It would just add another element to a possible mistake.
I would just increase both filters by a stop or two by setting a smaller aperture to begin with.

Is that normal to have 3 stops difference between filters? I use black and white filters which is usually less than half a stop difference.

Lachlan Young · Mar 1, 2024

awty said:
Is that normal to have 3 stops difference between filters

If you're attempting to make a pretty simple job excessively laborious via use of split-grade, yes. There are known differences in stops of exposure between the two exposures which can be used to define the 'real' grade in use - e.g. there might be something like a 2-stop difference between the two filter exposures to hit an effective G4 - i.e. 16s of the high contrast filter to 4s of the low. A dense, contrasty neg (or a flat one, in the opposite direction) will cause a large variance between the 2 exposures. If people don't like these relationships, then why are they using split-grade in the first place?

Pieter12 · Mar 1, 2024

I think there might be something wrong in your technique. I have been split-grade printing for over 5 years and only print that way. I have never had such a disparity between exposures. My method is to use the 00/yellow exposure that gives me the slightest bit of detail in the highlights, followed by the 5/magenta exposure to fill in the rest. Your times would indicate nothing I have seen in my darkroom. If you need such a long exposure to get your highlight detail, you might want to try flashing the paper first and using a shorter yellow time, or burning the highlights with the 00 filter.

MattKing · Mar 1, 2024

For negatives like that, start with the 5 filter test strip, and follow with the 0.
You might also consider using the 4 filter instead of the 5. When you do that, you end up decreasing the 0 exposure.

Bill Burk · Mar 1, 2024

I’d worry more about the f/stop not being correct causing you to get results that don’t match the test strip. It’s the old problem: do you move the setting towards closed then open to the click stop or do you move towards open and stop down? If you are not consistent your test strip may not match your final print.

koraks · Mar 2, 2024

awty said:
Is that normal to have 3 stops difference between filters?

Yes. Easily. Your filters are so close together because they're deliberately matched to be so. They block most of the blue light, and a tungsten/halogen lamp doesn't emit much of that to begin with. The blue emulsion is way faster than the green one.

pentaxuser · Mar 2, 2024

If for all the reasons given it is sensible to avoid changing aperture, is there any reason why the inclusion use of a suitable ND would not work?

pentaxuser

Fatih Ayoglu · Mar 2, 2024

I actually do that for RA4 prints but when there is 2-3 stops difference on BW prints, the low grade part takes too long. I guess I should be not so lazy

Pieter12 · Mar 2, 2024

koraks said:
Yes. Easily. Your filters are so close together because they're deliberately matched to be so. They block most of the blue light, and a tungsten/halogen lamp doesn't emit much of that to begin with. The blue emulsion is way faster than the green one.

I beg to differ. I rarely see 3 stops between filters. That would essentially be a fraction off one grade extreme or the other.

Pieter12 · Mar 2, 2024

pentaxuser said:
If for all the reasons given it is sensible to avoid changing aperture, is there any reason why the inclusion use of a suitable ND would not work?

pentaxuser

That would most probably be the simplest solution if the enlarger has a filter drawer. But I have a hunch those times are not right.

Fatih Ayoglu · Mar 2, 2024

Pieter12 said:
I beg to differ. I rarely see 3 stops between filters. That would essentially be a fraction off one grade extreme or the other.

I’ve never said all my prints require this but it was more of a question if it is ok to do so if and when I need it

Changing aperture during a session

Fatih Ayoglu

koraks

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Don_ih

Pieter12

Fatih Ayoglu

Fatih Ayoglu

koraks

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pbromaghin

Fatih Ayoglu

Don_ih

pbromaghin

Fatih Ayoglu

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Maris

awty

Lachlan Young

Pieter12

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Bill Burk

koraks

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pentaxuser

Fatih Ayoglu

Pieter12

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Fatih Ayoglu

Changing aperture during a session

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