HP5 at wrong ISO...developing suggestion...

[Voyager]

I just finished a roll of HP5 that was exposed at 1600 (forgot to adjust camera), and I'll be developing on Monday or Tuesday in DD-X (1:4). I'm OK with fairly high contrast and some grain. If I develop for 800 I think I risk losing a few frames but I'll get reasonable grain--close to 400, and developing at 1600 I think I might get very high contrast, and excessive grain. Would you agree with that?

 

[MartinP]

I'm unclear on the reason for not following the Ilford recommendation of thirteen minutes, after all they manufacture both the film and the developer. You can always clip-test the roll or, better, shoot a couple of similar shots on a different roll of HP5 and clip that. Exactly what you get will depend on exactly how you metered and exactly how consistent the lighting was, as usual !

 

[pentaxuser]

For most of its own films with its own developer Ilford gives pretty good times. I have always found that Ilford times for HP5+ in DDX are very close. If you have exposed it at 1600 then go with the 1600 times. After all if you had consciously chosen to expose at 1600 you would presumably use the Ilford times.

Don't worry. The film won't know that you exposed it at 1600 by mistake :

pentaxuser

 

[Voyager]

M and P: I am aware of Ilford's recommended development times, and had I intentionally exposed for 1600, I'd certainly have developed for that. However, I am concerned with the results seen on the eventual print--developing a strongly pushed 400 film at Ilford's 800 and 1600 specs...possible excessive grain at 1600 vs the chance of ruined (underdeveloped) frames at 800. I was sure that others had processed at both conditions, and it would have helped me to know of their results.

 

[hpulley]

Two stops underexposed will likely yield very thin negatives. I'd much rather have properly developed negatives any day. There will be grain but that is likely more useful than thin negs with smaller grain. By the time you overexpose/develop the prints to compensate you'll likely get more grain that way anyhow.

 

[archer]

I am loathe to suggest that if these are terribly important films, I would use Mercury latensification before processing. The procedure is to find a light tight cardboard box and cut a hole in the bottom into which you can place a metal jar lid tightly so no light can enter and in room light place 1tsp of liquid mercury in the jar lid. now in the darkroom place the film on a reel and set the film in the box and seal the box so no fumes can escape. Take the box outdoors and using a heat source such as a lighter or match, heat the metal jar lid protruding from the box for 30 seconds to 45 seconds. The heated mercury will produce mercuric vapors which will raise the film speed at least two stops. let it cool for an hour and in a light proof and well ventilated area and wearing breathing protection, open the box and place the film in the tank to be processed. Pour the remaining mercury back into its glass vial and save it for another day. I have used this procedure many times when I was an astrophotographer and the results are nothing short of miraculous. This should be the last resort to use to salvage grossly underexposed films and is exceedingly hazardous without the proper precautions. This is a completely different procedure from gaseous intensification using heated nitrogen under vacuum to super sensitize film before exposure. A technique also used in astrophotography. Proceed at your own risk and be careful.
Denise Libby

 

[Christopher Walrath]

I go with the above. Expose another roll film similarly and clip test it to get the times, et al. you desire and go from there on the goos roll. If you wanna get it right, do it right so you KNOW what you will get.