I accidentally exposed a roll of 120 Delta 400 film at EI 50, thinking I had Delta 100 in the camera. Does anyone have experience of developing Delta 400 in Ilfotec HC (like Kodak HC-110) at this speed? My current thoughts are to use a dilute solution to lengthen developing time and reduce the risk of error.
I'd develop normally, unless the subject had an excessive SBR (subject brightness range). If it did, develop about 15% less then nomral. Current BW negative films have a tremendous amount of "overexposure" tolerance. You'll get great tonal separation throughout the scale at the cost of a very slight increase in grain and loss of sharpness.
This is the (un)intelligent layman asking a question here but how about trying Perceptol instead? There is at least a one stop reduction here so presumably this reduces the D400 to 200.
It is now only two stops over exposed. Presumably whatever downside there is to reducing development to try and correct the problem is now tempered because the reduction can be less than would be the case with a "box speed" developer?
I'd be interested to hear if my "logic" stands up to scrutiny or does it have a flaw?
If it's flawed then it's of no help. So in that case,apologies in advance Tom.
I'd do it in Perceptol if you can get some in time for when you need it. Delta 400/Perceptol is a great combo, and it puts you a stop closer as Pentaxuser states.
I think a very dilute Rodinal in stand development would be the best course of action. Try a 1:100 for 20 minutes. Agitate the first 30 seconds only and let it stand. Dump it and rinse and fix normally. If you use HC110 at normal dilution and only cut back 15%, prepare for negatives which look like charcoal bricks. Good luck. Let us know how things turn out.
I developed two strips of test exposures (SBR 4) on Sunday, one in Rodinal (as rusty71's suggestion) and the other in Ilfotec HC. The development time for Ilfotec HC (5 minutes @ 21ºC, double dilution) was a guestimate but provided good contrast. I used that time to develop the original film in question, and the negs look fine from first glances.