Reciprocity failure as it relates to paper

[Pfiltz]

to Printing. I've heard the term when shooting film, but how does it relate to printing. Are we talking about it while exposing the paper, or the development of the paper? Just started my DR, and trying to figure all this out. So far, all I've done are 5x7's and (1) 8x10.

Last night I was trying to get the most out of a negative that was shot in Seattle earlier this year. I did a step wedge to kind of figure out my base exposure, which was 45 seconds @ f22, on some Ilford RC paper. I was using a No.2 filter, and did 4 separate exposures and ended up at 1.30 seconds @ f22, while dodging / burning ... Close to what I want, but not quite there.

Does Reciprocity failure come into play in the darkroom during the development phase? I was developing for 2.15 seconds in Arista.

Thanks

 

[jeffreyg]

I've never experienced reciprocity failure when printing but you might consider accommodating for "dry down" where the dry print will appear darker than it did wet in the fixer or wash. My experience and impression is that most of these photographic nuiances and effects are personal for each photographer and darkroom (doing the same thing I do in my darkroom may give you a different result in yours). Charts, graphs, mfg's recommendations and advice should be a starting point and tweaked to give you the result you desire.

http://www.jeffreyglasser.com/

 

[rbeech]

For practical purposes paper does not have reciprocity failure. I learned this the hard way when using in-camera paper negatives.

 

[Pfiltz]

Rbeech, I didn't think so, but I kept reading and/or seeing that term mentioned in the Darkroom area, so I thought I'd ask.

Thanks all.

 

[MartinP]

If you can manage it, don't stop down so far as it will really reduce the sharpness of the image. Your enlarger may have neutral-density built-in, if it is the diffusion type, or use a piece of ND filter in the filter tray. Small enlargements are sometimes tricky with a bright enlarger as the time is short, but a tiny aperture (and hence a bit of diffraction) might not be the best solution. To save fiddling around with step wedges use your contact-sheet as a sort of enlarging-meter. Do a search on in here for contact-prints and maximum-black.

 

[Pfiltz]

Thanks Martin. I have the Omega D2, and it has a filter tray. I'll pick up some ND filters as well. I do have a contact printer too that I can use.

Right now, I'm just stumbling along in the DR learning as I go, and trying to read up on it as much as I can here, and watching some YouTubes.

Matter of fact, while I was waiting for my enlarger to get put together, I was doing contact prints in the bathroom, because I just had to see what these neg's looked like. Been building up a small inventory of 4x5's,

 

[Mike Wilde]

ra-4 colour paper has reicprocity failure, as well as cross over of curves at long exposure times. Most sources advise to keep ra-4 expsoure times between 5 and 30 seconds.

 

[MartinP]

Oh, my apologies - I missed the bit of your sig which mentions 4x5". With such relatively small magnification factors there would be hardly any fuzziness to see. It can be more noticeable with 35mm for example.

 

[MattKing]

Ilford makes black and white paper for digital exposure as well. The spectral sensitivity data for that paper is based on an exposure time of 1/10,000 of a second.

I point that out as an example of where paper has been optimized for a particular exposure range.

So I would suggest to the OP that it is wise to do your best to keep exposures within a practical range of about 2 - 90 seconds.

And f/22 isn't usually the best aperture on a lens.

 

[Photo Engineer]

Paper has 2 kinds of reciprocity failure, speed and contrast.

In speed reciprocity failure, the paper loses speed with exposures much above about 1 minute and it gains speed below about 1 second.

In contrast reciprocity failure, contrast goes down with longer exposure and up with shorter exposure.

These effects vary vastly among papers, but can be disastrous with VC papers where you are trying to design matched reciprocity failure between 2 emulsions.

Some papers have virtually no reciprocity failure, others have a lot. Some papers for example, are designed to work in different ranges. Digital papers are designed to work with high intensity short exposures and if you use them on-easel, they will respond differently than the mfgrs. data sheet.

Historically, Kodak made 2 ranges of papers. One for high intensity short exposures and one for low intensity long exposure.

PE

 

[Pfiltz]

Thanks PE

 

[Bill Burk]

Thanks PE,

MattKing pointed out the paper intended for electronic exposure may be susceptible to reciprocity failure. You probably won't encounter that paper. I was thinking of getting some, so it might pertain to me one day.

If I understand, with an Omega 4x5 enlarger and normal paper, you will not encounter reciprocity failure. Even if you did, the practice of making test strips completely negates the impact - because you would be testing the actual results you get for the actual times you expose.

 

[brian steinberger]

As mentioned, don't stop your lens down to f/22. Use f/8, +/- a stop if necessary and none of this will be an issue..

 

[Photo Engineer]

You can run into it between 1' and 10".

PE

 

[MattKing]

You can run into it between 1' and 10".

PE

PE:

For clarity, do you mean with times between 10 seconds and 60 seconds (1 minute)?

 

[Photo Engineer]

Yes, sorry, 1" and 10". Kodak made papers for photo labs with the aim centered at 1' or shorter and another range of papers for enlarging with the aim centered at 10" and above. We used to run 2 tests on each emulsion or coating to see which range it would be most suitable for. We also used to base experiments on these two ranges.

Usually the one paper was sold in narrow rolls and the other was sold in sheets or wide rolls.

In the case of color, the curves were adjusted slightly to favor neutral for the narrow paper, and slightly pink for the wide and cut sheet. The latter was to make flesh tones and whites more appealing, as the majority of prints were of weddings or were portraits.

Reciprocity failure was critical in this case as color could shift.

PE

 

[DREW WILEY]

Brian - you're assuming that everyone else's enlarger is the same as yours, whereas enlarger light
sources vary dramatically in terms of light output, just as different papers have different effective
speeds, which is complicated in the case of VC papers. Color enlarging can present distinct recip
challenges, depending on what you are specifically doing. Current RA4 papers are generally cooperative because they tend to print quickly on most colorheads. Although current Crystal Archive
options are used in laser systems, they balance just fine in ordinary optical printing - they're deliberately engineered dual-usage.

 

[Bill Burk]

I assumed black and white paper, where using a test strip would completely mitigate contrast or speed changes due to reciprocity law failure... Because it provides a proof of actual results.

For color printing I recommend avoiding reciprocity failure by exposing for approximately the time the paper is optimized for.

 

[RalphLambrecht]

yes, making a test strip under actual conditions is the best idea!The math gets you close but not necessarily on target.