Reciprocity failure of Delta 3200

[ulrich.von.lich]

Hello,

I'm going to take some photos in a forest at night, which would be tripod long exposure work. I'm aware of the fact that low speed films such as Acro 100 have generally less reciprocity failure. But I'm trying to reduce my working time to the minimum.

After having read the fact sheets, I was surprised to find out the Delta 3200 actually had better reciprocity failure rates than the TRIX. For an exposure of 10s, the TRIX requires in total 50s while only 30s requires the Delta 3200. For such an exposure, it's also faster than any ISO100 film regardless if it suffers from the reciprocity failure or not.

I'd like to know if anyone has long exposure experience (i'm talking about 1s to 30s) with the Delta 3200. I don't mind the usual grain of the Delta 3200. But will it increase with the exposure time? Also, will the compensation time vary with the rated speed? Ilford didn't mention it on the long exposure chart, so I suppose it's based on the box speed?

http://www.ilfordphoto.com/Webfiles/201071394723115.pdf
http://www.kodak.com/global/en/professional/support/techPubs/f4017/f4017.pdf

Best Regards

 

[thegman]

Never used Delta 3200 under those conditions, but Kodak BW400CN requires no adjustment up to 2 minutes, so even thought it's slower than Delta 3200, maybe your exposure times would not be all that different.

 

[Tim Gray]

From what I've read, Delta 3200 and T-Max 3200 have decent reciprocity behavior for such fast films. Tri-X is particularly bad. Also from what I've read (and remember) in the Ilford spec sheets leads me to believe they don't provide individual reciprocity compensation information for each film since they all seem to have the same values (at least the Deltas). T-Max films give different values for each of the speeds.

Here's some hard data about some films:
http://web.archive.org/web/20070911063831/http://www.robertreeves.com/b&w.htm

The 2-minute ISO of TMZ from that page is 667, which isn't too bad considering it's actually an 800-1000 ISO film. Which means it IS actually faster than a slower film for some long exposures. Unfortunately there's no data for Delta 3200.

 

[Chris101]

This looks like an area that requires some research.