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HP5 exposed at 100, help.


stan_o

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Ok, so I did a not so smart thing and didn't correct the film speed

on my light meter and exposed HP5 at 100 for some 12x20 negs. I

have Rodinal, Ilfosol S, and I suppose I could find some D-76 if

need be, but prefer to use Rodinal. I have not done a lot of

pull/push processing and could use some help dialing in an intial

development time. My intial calculations leave me at very very

short development times that I feel will not yield decent results.

 

Thank you.

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Rodinal 1:100 for 20 minutes is the universal cure for just about everything. Tri-X

exposed at 200 has nice gradation with this dilution. HP-5 should give similar results,

with a little more 'beef' to your shadow densities. Be sure and use enough total

solution to keep from exhausting the developer prematurely. By my calculations, you

should use 20ml of concentrate in 2 liters of water for a minimum volume per sheet

of 12x20. BTW, I am assuming that you are targeting silver gelatin printing with the

negative.

 

Clay

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I agree with Clay. Both with Tri-X and HP-5, there's no real difference in developing time when exposed at 100 or 200. So, a development time at 200 will pretty well get it with exposure at 100. I suppose someone who has conducted extensive densitometry studies will scientifically refute this, but my eyes on the prints see no difference.
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I've been using HP5+ for years in D 76 1-1. I'm a little surprised to read that there is little difference between EI 100 and 200. I rate it at 200 and there's a pretty big difference between that and 400. I would have expected a similar difference between 100 and 200. However, I've never exposed it at 100 (my usual mistake is the other direction, which is much worse) and others apparently have so I'd probably guess wrong. FWIW, if it were me I'd develop the least important negative in my usual developer at N - 1 and see what it looked like before switching to a developer I've never used before. But maybe the Rodinal idea is better. The good news is you can make a bad guess without losing everything because you have sheet film. The bad news is it's 12x20 sheet film.
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I have to disagree with the two previous posters...I believe they're <i>slightly</i> off the mark.<p>Agfa recommends rating TriX at 400 but HP5+ at 160 when using their Rodinal developer at 1 + 100 for 20 minutes 68 degrees.<p>Your HP5+ at 100 will be overexposed/overdeveloped about half a stop if processed in Rodinal at 1+100 for 20 minutes. And whats that mean? At this point it's all conguncture...I don't believe your highlights will block but that depends on many things, quality of light you were shooting in being one.<P>And so what would I suggest? Agfa recommends 15 minutes at 1+100 for HP5+ shot at 100 <i>when using hand tanks</i>. I believe they also presently recommend a minimum of 5 mls of concentrate (it used to be 3 mls) for every 80 square inches of film. I'm enclosing a an Agfa pdf for you to study.
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Thanks much for the help and the pdf files. I will go with Rodinal, as that is what I am most comfortable with. I will shoot a test neg or two and go from there. The negs are of my cousin's wedding and I am going to feel horrible if I screw them up!
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I forgot to add a question, what is the "norm" for reducing or increasing development time in push/pull situations. I have seen different times expressed for compensating developers vs. other types of developers. Some say 10% per stop, some say 1/3, it makes it down right confusing! My standard developer is Rodinal, mostly mixed at 1:50. Again, thank you.
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<i>Some say 10% per stop, some say 1/3, it makes it down right confusing</i>...</i><p>Stan...great question; I'd also like to know BUT I think it's very film/developer/method dependent.<p>I wonder about the suggestion where you would test with 35mm HP5+ to get a time for your sheet film. Do you think thats a good idea? I know that there is often somewhat of a difference between 120 & 35 versions of a given emulsion.<P>I think as long as you use dilute Rodinal (dilute so that it can act as a compensating developer) and proper agitation (to keep the highlights in their place) you should be fine. Where a person may really have problems is if as another poster mentioned you shoot HP5+ at 400 then process it as if it were 100 (or 160) You're setting yourself up for problems then...or you are if your sheet HP5+ acts like my students 35mm HP5+ does.
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Stan: If the images are important, and it sounds like they are, don't guess and experiment. Take a sheet or two of HP5 (it doesn't have to be 12X20, to save some money) and expose it with the same meter error under similar lighting conditions (i.e. sunny, overcase, etc.) and experiment with that. When you get the results you want with those tests, then start on the real images. If you have a densitometer, this can be more scientific. Place a Zone VIII where it should go with the wrong meter setting and develop the film until your test Zone VIII is the density you get when you normally expose and process film.
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HP5+ in D-76 (or Rodinal, for that matter) has a fairly straight-line curve shape for _at least_ 14 stops. So it's certainly not going to block up.

 

These are big negs; graininess shouldn't be a concern.

 

Two stops extra exposure will give lots of shadow density, effectively _lowering_ contrast, so imho the last thing to do is further lower contrast by reducing development.

 

So I suggest develop normally in the developer of your choice. Since they're important films be sure to test first.

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