I am trying to understand how different developers can affect film speed.
From reading, my understanding is that a developer can quite easily make an ISO 400 film act more like ISO 600 or on the opposite side act more like ISO 200.
I don't have the facility to do and serious testing and was wondering if anyone has done any tests on the following developers, and what their findings were.
- Kodak HC110
- Kodak XTOL Replenished
- PyroCat HD
I'd not worry about it. Plus or minus a third of a stop or so should not keep you awake at night.
If you have the facility to develop film then you have the facility to test. Don't be daunted - you don't need extensive testing to establish film speed and development times. Also, if you want a film to act like a 400 ASA film, then use a 400 ASA film! It might be helpful if you explained a little more what it is you are trying to do.
I was actually reading a webpage which mentioned that certain developers and I think HC110 was mentioned that actually slows the film down during development. To be honest I am not 100% what they mean.Originally Posted by docw
It got me thinking though, if developers can affect film speed, do we need to be concerned about this at the exposure time
No they can't, and no we don't.
There are numerous recommendations regarding film speed, exposure, and development.
Each is tailored to the particular tastes and shooting habits of its author.
When you get deep enough into the technology and technique that you can produce 100% consistent prints from a variety of subjects, then you're ready to explore variations that might make your shots more pleasing to you.
But not before.
I've been shooting and developing B&W since about 1950, using box speed and manufacturers' recommended development times. I'm quite pleased with the results... and nobody else cares.
- Leigh
If you believe you can, or you believe you can't... you're right.
From someone with over 50 years experience, thats good enough for me
Ian,
You've got just about all the advice you need. The developers you listed will give you "box speed" for any film commercially available. Go shoot film. Expose it as recommended by the manufacturer. Develop it in any of the soups for the recommended time. The results will be fine.
The only thing you can really do "wrong" with B&W or color negative film is to under-expose. You can over-expose by an enormous degree (by as much as 5 stops) and you will still get excellent results. In fact, rating film at 1/2 or 1/4 box speed (1 or 2 stops more exposure than box speed) often results in increased quality and improves color rendering.
Go shoot. Don't worry about any of those developer formulas.
Rich
Last edited by Rich14; 13-Oct-2017 at 15:18.
Thought excercise: Any one correct me if I have this backwards.
If HC110 dev time is 8 minutes for a given 400 speed film per manufacture. And lets assume that you get a meter reading of f16 @ 1/30 sec . That will give specific densities over base + fog for each of the different zones . A step wedge exposure helps to see this more clearly.
So if you expose your Film at EI200 you are over exposing because your meter will tell you to use 1 stop more f11 @ 1/30 or f16@1/15 - Thus your densities at 8 minutes of development will be more dense for your image zones and will show more shadow details but less details in highlights (maybe).
If you expose your film at EI800 you under expose by one stop and thus if you process for 8 minutes your negative densities will be lower than your normal 400 with less shadow detail but more control over highlights.
If you Decide EI200 is really what you want to expose 400 speed film at, you still have the flexibility to adjust development time to control negative density and contrast. Different developers will yield different results. Agitation method also comes into play to a lesser degree unless you are using rotary/aggressive agitation or on the other end of spectrum minimal agitation. With minimal agitation you would increase dev time, with rotary decrease it.
Most photographers pick an EI and time that gives them the range of tones they like to print with on a given paper. If you only use grade 2 paper you try to tailor the zones on the negative to reflect accurately on that paper.
As long as your negative densities are in the ball park with the density and contrast you want, then modern Variable Contrast papers allow you some additional flexibility.
The magic you are looking for is in the work you are avoiding.
http://www.searing.photography
Drop the term "ISO" and instead consider "EI" - exposure index.
Yes the ISO is determined by the manufacturer, as tested with the developer and methodology they employ. This generally has little bearing on the end user's process, and specifically when you talk about more exotic developers like Pyrocat there is a definite difference in your EI because the manufacturer did not test the film with that developer. There's also the issue with what exactly "ISO" is - see the historical change in film speed standards, etc.
I know that for most of the films I use, Pyrocat as well as Rodinal tends to cut my film speed by 2/3 to 1 stop. If I exposed at "box speed" I will lose shadow detail. Of course this is determined by your meter, your metering technique, your development time, temp, and agitation scheme, etc. etc. XTOL tends to give me a higher EI than box. Your EI more specifically gives you a speed at which the shadow detail falls appropriately on your negative/print.
If you don't want to do formal testing (as I don't, generally), the common recommendation is to shoot everything at half box speed. Alternatively, just bracket one scene at box as well as +/- 1 stop and see what you get. Adjust to taste. When trying out a new film/developer I do that and then adjust for the next time. I can usually hone in on a good EI and dev time after a few sheets.
The three developers you listed (and most general purpose developers) will give you essentially the film's ISO speed within a small fraction of a stop. XTOL will yield very slightly higher speed than the other two. All other things being equal, the same differences would be found when running an EI test, except that the target EI is 2/3 stop below the ISO speed.
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