Reciprocity Failure...

[heespharm]

Duly noted and deleted... The AA pics were just for a friend to convince him to do the app... I couldn't find the original post but I knew I had the PDF somewhere... Sorry to offend

[Lee L]

Duly noted and deleted... The AA pics were just for a friend to convince him to do the app... I couldn't find the original post but I knew I had the PDF somewhere... Sorry to offend

Thanks very much. I'm not offended. I just don't want the info stuck on the internet without proper context and without credit to the folks whose work I used to derive the results. Better to refer people to the original, and you have that info now. I know it's hard to find older posts here. APUG is in serious need of a much better search facility.

Lee

[jp80874]

It is early in the morning at this reading, but I don't see mention of what format you are using, simply “multiformat.” If you are using a view camera you may need to add a bellows factor. Search here and the large format forum if you are not familiar with “bellows factor”. If you have a large bellows you may need to add more exposure, several stops.

When experimenting with night photography in any format, or even work in deep shadows, it is money well spent to bracket your exposures. By that I mean add at least two stops to the exposure you think addresses all of the above, including reciprocity. It is reasonable to assume that you can make a pretty usable print one stop on either side of the correct exposure. If your bracket is two stops more than the maximum exposure you think you need, this will give you a six stop range for your experiment.

If this is not enough exposure then reconsider how you are metering. Consider a gray card, consider an Incident Light Meter which measures the light that hits the subject. It all boils down to the old standard “metering for the shadows, printing for the highlights.” If your first experiment doesn’t give you the detail you want, shoot it again with much more exposure and then bracket with two more stops (yes, doubling the time for each stop).

The joy of experimenting in the neighborhood is that it gets dark every night. You experiment close to home, learn what you need, so that you know what you are doing when you go on an expensive trip. I hope this helps.

John Powers

[njkphoto]

Thanks John I am using a 6x9 Mamiya. I am going to try the Neopan Acros now after using the FP4. As I said earlier I was surprised that I got a legitimate negative without any time change. Now, since I used the times from the chart above I am wondering if I should develop it a bit less from the 11 minute it calls.

[jp80874]

Thanks John I am using a 6x9 Mamiya. I am going to try the Neopan Acros now after using the FP4. As I said earlier I was surprised that I got a legitimate negative without any time change. Now, since I used the times from the chart above I am wondering if I should develop it a bit less from the 11 minute it calls.

Sorry. Can't help there. I use HP5 or T-Mx 400 and Rollo Pyro in a Jobo CPP-2. There is no grain that you can see in 7x17 contact prints. I have read that Neopan Acros has much better reciprocity characteristics that HP 5 or FP 4, but it is not available in the size I shoot, so I have no personal experience.

John

[njkphoto]

Yeah I got some Acros and according to the specs there is no need for time compensation up to 120 seconds. I will try it soon. Again, it was interesting to see that the results on the FP4 were good at 8-15 seconds with not change in time at all.

[Jeff Bannow]

Yeah I got some Acros and according to the specs there is no need for time compensation up to 120 seconds. I will try it soon. Again, it was interesting to see that the results on the FP4 were good at 8-15 seconds with not change in time at all.

I think you will find when you print them, that the shadows are too thin.