Underexposure Issue with Pan F+

[David R Munson]

I've been shooting a fair amount of Pan F+ and the results have generally been excellent. However, I've shot a handful of rolls with a #29 deep red filter and despite generous exposure compensation I come out with negatives so thin as to be totally useless. I've tried some crazy exposure compensation, making sure my developer isn't bad, etc. The only thing I can think of is that I'm venturing into the territory where this film's red sensitivity starts to drop off. Has anyone here ever run into this problem? Does a spectral sensitivity issue seem like the culprit? It's the only thing I can think of at this point because I've gone over every other factor and ruled it out.

EDIT: Forgot some specifics. I usually shoot it at EI 32, which gives me an EI of 2 with a #29 red filter. Development has been in both HC-110 and D-76. Mostly shot with a Mamiya 645 Pro with an 80mm f/1.9 wide open. Incident metering.

 

[Chriscrawfordphoto]

I think a #29 needs four or five stops MORE exposure than normal. I know for sure that the more common #25 red requires 3 stops (I use that one) and the 29 is a deeper red.

 

[David R Munson]

I've been making exposure corrections in that range, but to no avail. Same filter with other films with similar corrections (4+ stops) gets me fine results.

 

[wde60]

Pan F Plus gets into significant reciprocity failure with exposures over the one second range. Did you figure that in?
It looks like at measured exposure time of 5 seconds you need to adjust to 12 seconds, and for a measured time of 10 seconds you should adjust to 30 seconds:
http://www.ilfordphoto.com/Webfiles/2006216115811391.pdf

 

[David R Munson]

I thought of that, but none of my exposures were that long. Most of the work was in full sun shooting wide open. At EI 32 that's 1/2000 sec at f/1.9 without filter correction. With filter correction that puts me around 1/250 or 1/125 for most exposure.

I did dig up a sensitivity graph for Pan F+ and it does look like sensitivity begins to drop off severely just after the point where a #29 would start transmitting.

 

[Trius]

I thought of that, but none of my exposures were that long. Most of the work was in full sun shooting wide open. At EI 32 that's 1/2000 sec at f/1.9 without filter correction. With filter correction that puts me around 1/250 or 1/125 for most exposure.

I did dig up a sensitivity graph for Pan F+ and it does look like sensitivity begins to drop off severely just after the point where a #29 would start transmitting.

Your math is wrong. 1/250 is only 3 stops, 1/125 only 4 stops.

 

[dof]

It's likely not too late to do some intensification on those negs. I've used selenium toner in the past on images that didn't print well on a grade five paper. After adjusting dilution and times on a couple of snip tests, the rest printed outstandingly at grade three.

I'm still a fan of that poisonous stuff.

 

[David R Munson]

Your math is wrong. 1/250 is only 3 stops, 1/125 only 4 stops.

The point remains, though. IRL I gave it plenty of exposure.

It's likely not too late to do some intensification on those negs. I've used selenium toner in the past on images that didn't print well on a grade five paper. After adjusting dilution and times on a couple of snip tests, the rest printed outstandingly at grade three.

I'm still a fan of that poisonous stuff.

I'm all for trying it, but it'll have to wait a while. I'm moving to another continent.