Film Reciprocity Failure Compensation Factors For Films

[GoodOldNorm]

I have the chart for Ilford films, would any of the members here be kind enough to contribute their filter factors for films other than those made by Ilford. Thank you in advance.

[Alan Klein]

Why don't you post the ones you have for Ilford?

[Michael R]

Why don't you post the ones you have for Ilford?

Ilford reciprocity compensation factors (I think this is what OP means, and he wants equivalent info for other brands):

https://www.ilfordphoto.com/wp/wp-content/uploads/2017/06/Reciprocity-Failure-Compensation.pdf

Trivia: I am responsible for Ilford having gone through this exercise :) I was not as successful with Kodak unfortunately.

[r.e.]

If you use iOS, the app Reciprocity Timer is US$1.99. There are in-app purchases, but the additional functions aren't necessary if all one wants is reciprocity failure.

[Neal Chaves]

Don't apply reciprocity exposure and development corrections for long exposures (1/2 sec. +) based on published data. Test for yourself after you have experimentally determined exposure and development schemes and you may be surprised. I wasted a lot of time and effort producing long exposure negatives that were thick and flat. When I finally tested, I found no compensation was required for TXP or now HP5+ out to one minute.

[Benjamin]

If you use iOS, the app Reciprocity Timer is US$1.99. There are in-app purchases, but the additional functions aren't necessary if all one wants is reciprocity failure.

I have both Reciprocity and Exposure Assistant on my Android phone. Exposure compensation & times are similar when you compare them using the same film and metered time. Experimenting is essential, but having these as starting points helps.

[GoodOldNorm]

I have both Reciprocity and Exposure Assistant on my Android phone. Exposure compensation & times are similar when you compare them using the same film and metered time. Experimenting is essential, but having these as starting points helps.

Does the margin of error matter less on exposures over 30" as long as its a few seconds in favour of over exposure?

[Conrad . Marvin]

The longer the exposure, the less important the exact time is.

[Michael R]

Ilford did the work properly. Their revised factors are good.

Kodak unfortunately only provides high level/rough indications in their tech docs so best to use their info like bookends and extrapolate.

John Sexton suggests a series of adjustments for the TMax films and TXP.

Howard Bond published the results of his reciprocity tests for various Kodak and Ilford films. This was back when Ilford still only had a single generic reciprocity adjustment graph for all of its films before the revised, film-specific factors were published in 2017 after the work was done.

[Benjamin]

The longer the exposure, the less important the exact time is.

Exactly. Less impact in adding 10 or 20 seconds to a compensated time of 21'52 to doing it with one of 1'26".

Best practice for me has always been try it first with the manufacture's given times (when available), experiment later.

[Alan Klein]

I have both Reciprocity and Exposure Assistant on my Android phone. Exposure compensation & times are similar when you compare them using the same film and metered time. Experimenting is essential, but having these as starting points helps.

What app?

[Doremus Scudder]

Here's Howard Bond's article. https://www.willwilson.com/articles/0403Bond_Reciprocity2.pdf

Some of the results are likely outdated, but methodology, etc. are still valid.

You can use these as starting times for Kodak materials (I find they are close with TMY and 320Tri-X out to 20+ minutes).

For Ilford, use the data that Michael R links to and make yourself a chart.

Best,

Doremus