Pushed films and reciprocity

[aeiffel]

I'm currently experimenting with my favourite films in diafine -

mostly APX100, Tri-X and Pan-F. Till then I mainly shot in daylight

conditions or above/below exposure times where reciprocity failure

might occur.

 

As I plan to give some night shots a try soon, I'd like to know if

films "pushed" in diafine will have their reciprocity characteristics

changed or not. I've never fallen below reciprocity with pushed films

and wonder about the results if I correct exposure time according to

the manufacturer's curve (especially with tri-x).

 

I guess my problem also is I'm used to shorten development in rodinal

for long exposed negs, and diafine doesn't let me play with this...

 

Thanks for your input.

[lex_jenkins]

I don't concern myself with the technical aspects of reciprocity when using films like Tri-X, FP4+, etc., at night with exposures ranging from several seconds to an hour or longer.

 

One reason I prefer Diafine and, alternatively, dilute Rodinal (with stand development) is to further diminish the need to concern myself with identifying the precise EI for such exposure conditions.

 

For example, in daylight EI 1200 with Tri-X in Diafine suits me. For nighttime photography of objects illuminated by the full moon I'll estimate it at EI 400. Close enough for my purposes when I want my photos to look as tho' they were taken at night, yet still adequately exposed.

 

Because Diafine develops to a fixed degree it's suitable for bracketing exposures, a fact that may help you in your experiments with various films.

 

FWIW, I've gotten good results with APX 100 at EI 250 in Diafine, tho' I haven't tried this combination of film/developer for nighttime photography.

 

FP4+ at EI 250 seems about right with Diafine for daylight. Bracket appropriately to reach the desired exposure for nighttime photography. If your experience is like mine you'll find that EI 80-125 is about right for nighttime photos that look like they were taken at night with this combination of materials.<div></div>

[lex_jenkins]

BTW, technically, I don't consider this "pushing" film. I'm looking for negatives that are properly exposed and developed only enough to do the job. Unless I specifically want excessive grain and/or contrast for aesthetic appeal, I try to avoid overdevelopment. That's the beauty of using Diafine and stand development with very dilute Rodinal (1:100 or more dilute): it's easier to avoid overdevelopment.

 

OTOH, there are finer grain developers than either of those two. Tri-X in Diafine can be quite grainy under some conditions, especially nighttime photography.

[m0002a]

Reciprocity is a function of exposure time and is not effected by development or by using a speed other than the rated speed.

[lex_jenkins]

Here's a fairly recent thread referring to some research Howard Bond has done into reciprocity, published in a PhotoTechnique magazine article:

 

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=005T0P

 

I read the article. It's well worth buying a back issue for someone interested in the technicalities of reciprocity for certain films. I'm comfortable enough with estimating times.

[aeiffel]

Mark > Thanks for the confirmation. That's more or less what I expected.

 

Lee > Thanks a lot for your hints and pointing me to this thread. I've no experience with long exposure times so this paper sounds like a good starting point.

 

FWIW, the following EI look fine to me after a couple of tests in daylight conditions : tri-x @ 1250, Pan-F @ 64 and APX100 @ 200/250 (overcast/sunny).

As you may have guessed I'm not looking for pushing "artefacts" - hence my try with diafine, but grain is not really an issue. I'm much more concerned with blocked highlights and tonal range.

 

Also, would you mind to share some of your experiments results with stand development ? I already use 1:100 dilution with rodinal and be interested to know what your starting point was for such a process. Thanks again for your time and sharing your experience on this forum.

[lex_jenkins]

As far as I can recall offhand, all of my experiments with stand processing in Rodinal have been confined to Tri-X. I'm satisfied with the results I get developing for 2 hours in a 1:200 dilution.

 

If you do a search (using the "search" utility at the top of the page) using "stand development" as search terms you'll find many recent discussions of this technique. Add Rodinal if you wish to further limit the search.

[aeiffel]

Respecting the manfacturer's times for long exposures led to good results with diafine.

I tried several comparisons shots with tri-x @ 1250, even with 25" (following the correction for a 6" measured exposure) I still had nonblocked highlights.

This developer is damn great under certain circumstances.