ISO100 film best at ISO15 --- is that normal?

vicmortelmans

vicmortelmans

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Hi,

I was shooting my last roll of CHS100 (ADOX/EFKE) at ISO65 and did +/- 2 stops bracketing for one of the shots. Now it turns out that the best result is from the overexposed shot. So this means that this film is at best when exposed for ISO 15. Shots with lower exposure had less shadow detail and were more grainy.

My question now: should I make this my default exposure for this film, or do something else??

Now there are some side-constraints that may have to be taken into consideration.

First, it was a low-contrast shot. Overexposing by 2 stops in a high-contrast situation would most probably have caused blow-out highlights.

Second, I developed in Rodinal 1+100 for 15', agitating only once in the middle of development time. This contributes to a very wide density curve and prevents blown-out highlights.

Third, I tend to develop for thin film, to accomodate my (not-so-powerful) filmscanner. In this case, the less exposed slides were very thin, so again, little risk at blown-out highlights.

So what are my conclusions:

1) the conclusions are only valid for low contrast scenes

2) lost shadow detail won't come back (drastically) when increasing development, so ISO 15 is a good standard for this film in low contrast

3) development may be extended slightly (I think may go for 1+80 dilution, i.o. extending the time)

4) exposure is a main grain-influencer (more exposure - less grain)

5) OK, but what then if contrast is high? I already develop for a wide curve, so can only decrease exposure, not to burn the highlights. ISO 65 may do in that case.

Hmmm... looking back at my conclusions, seems like it's all back to the old "expose for the shadows and develop for the highlights"... Nevertheless, there's something new (to me at least): the zone system always starts from spot metering and stuff, while my guideline now only involves adapting ISO-setting (or using exposure compensation) on the camera depending on the environment contrast, while keeping development constant (have to, using roll film).

Groeten,
Vic
 
I don't think you have enough information to determine what the problem is. You simply could have made a mistake in metering. I would do a test if you want to find out what is going on.
 
What are you metering with? I just found my bessa R to be two stops off- dammit!
Glad to find that though, I now have yet another excuse for lame pictures.
 
Hi,

It's not my intention to shoot that slow. Shooting an ISO100 at 65 is more like standard procedure for me, but I'd never expected that ISO15 would give reasonable results.

Also note that my ISO65 shots are very acceptable but the ISO15 showed even better.

Here are a couple of ISO65 exaples:

Son:
CLICK

Two pals:
CLICK

As a matter of fact, I just now developed my second roll of CHS50, and it seems to please me. But I'll certainly do a bracketing test at ISO7 on this one 🙂.

And my next EFKE-order will certainly contain some CHS25.

The CHS100 was loaded on my Pentax Super A (SLR, horresco referens) with a M42 Jupiter 9 (FSU, that's OK). I don't exclude the metering problem and will double-check this.

Groeten,
Vic
 
Vic

Tom A says I don't dev for long enough (Rodinal 1:100 like you) , I have same speed problem but with 400 ASA, he suggests trying x2, i.e. 30 mins or more...

Your high lights may be ok mine rarely block.

Noel
 
I'd swear those were taken in Antwerp.

Also, I've read online some people shoot Agfa portrait at EI 20 instead of the advised 160. I've got some right here shot at 40 and 80 (need to scan though before I'm sure if it's any good)

So yeah it's possible, I think.
 
can I ask a question?

Why would a person buy an ISO 100 film if they had every intention of shooting it at 50 or even 25? Would you buy only Neopan 1600 to shoot at 400? If you aren't happy with the look or performance of a particular film at the box speed, why not just try a different film? What am I missing here? It just doesn't seem logical to continue using a film if the only results you find acceptable are ridiculously slower than what it's rated by the manufacturer.

To be fair, I often shoot Tri-X at something other than 400 EI. But it's not because I find the results at 400 unacceptable. It's because I find the results at other speeds acceptable as well, and it gives me a look and a flexibility that I don't get otherwise.

vicmortelmans-
It sounds like you prefer an under-developed negative for scanning. If that's the case, and find shooting 100 speed film at 15 EI but developed for 100 to be the best, something is wrong with your process. If your processing time/temp/dilution was remotely appropriate for the film, it'd be grossly over-exposed at 15 EI, not "thin." Either your developing is way off, or your meter is hopeless. There's nothing wrong with trying to find a speed that will work with those two possibilities, but I'd think you'd want to get your metering and your developing closer to some kind of standard before playing with exposure as a "fix." That way, when you eventually do try another film, you aren't starting out in a hole as far as getting acceptable results.

But that's just my opinion. I might be totally mis-understanding what you are going for here.
 
Last edited:
40oz said:
can I ask a question?

Why would a person buy an ISO 100 film if they had every intention of shooting it at 50 or even 25? Would you buy only Neopan 1600 to shoot at 400? If you aren't happy with the look or performance of a particular film at the box speed, why not just try a different film? What am I missing here? It just doesn't seem logical to continue using a film if the only results you find acceptable are ridiculously slower than what it's rated by the manufacturer.
Click to expand...

The box speed means nothing if you are testing to establish your personal EI. I do zone system tests for all my films with a densitometer and have found 60 to be my EI for TMax 100, 320 for Tri-X and 200 for Fomapan 400.

Doing this allows me to predict exactly the contrast range of the negatives and spot meter my scened precisely in terms of zones. When establishing film speed, I am interested in getting a density .1 above Fb+F - and so far none of the films that I have tested have given that at the box speed with my developer combo.

-Anupam
 
Anupam Basu said:
The box speed means nothing if you are testing to establish your personal EI. I do zone system tests for all my films with a densitometer and have found 60 to be my EI for TMax 100, 320 for Tri-X and 200 for Fomapan 400.

Doing this allows me to predict exactly the contrast range of the negatives and spot meter my scened precisely in terms of zones. When establishing film speed, I am interested in getting a density .1 above Fb+F - and so far none of the films that I have tested have given that at the box speed with my developer combo.

-Anupam
Click to expand...

I understand that, but there are at least two variables at work here - exposure and development. I'd kind of think if your "personal EI" was so far off box speed you'd either switch films or tweak your development further to get it to something more reasonable.

It just doesn't sound reasonable to me that someone would find a film is best three stops over-exposed, especially if "best" is negatives that are either under-exposed or under-developed. If the meter was accurate and the development was appropriate, the last thing you'd get from shooting three stops slower than box speed is thin negs.
 
40oz said:
I understand that, but there are at least two variables at work here - exposure and development. I'd kind of think if your "personal EI" was so far off box speed you'd either switch films or tweak your development further to get it to something more reasonable.

It just doesn't sound reasonable to me that someone would find a film is best three stops over-exposed, especially if "best" is negatives that are either under-exposed or under-developed. If the meter was accurate and the development was appropriate, the last thing you'd get from shooting three stops slower than box speed is thin negs.
Click to expand...

I'm not saying that the OP's EI of 15 for 100 rated film is normal. I can't tell what went wrong in his particular case without more information but it might have been the metering, as has been suggested. Unless one has a properly calibrated meter, testing for EI and development time becomes impossible.

BTW, when testing fot EI the development time isn't as important. The time mainly affects the higher densities and thus controls the contrast.

-Anupam
 
The way I establish my (contested) process is to start exposing at box speed and developing at standard development time. Then (in most cases) I find that my film is too dense for the scanner to catch the highlights without scanner noise (typically for high contrast scenes). To reduce the highlights, I decrease development time and increase dilution (so when I start at rodinal 1+50 10', I may end up at rodinal 1+100 15'). But then I notice that shadow detail is becoming low and therefore, I increase exposure.

Where's the flaw?

I can think of a few, but none that I can solve just now:

- my scanner's bad; I need a scanner that can cope with denser film
- I don't understand about high dilution (compensation) development and should increase development time drastically for rodinal 1+100 (as suggested by Xmas)
- it's all due to a bad meter (will do a test asap, but I don't have any 'calibrated' meter, only a couple of antique metered camera's with probably wrong batteries etc...)

Is there any way you can establish a process in a more or less objective manner and in one go? Now I just change parameters each next film, so it takes weeks or months to see the evolution.

Groeten,

Vic
 
Vic

I have similar problems, Tom A says I need to use 30 mins or 60 mins... I'll try this.
Try meter on sunnay day it should agree with exposure recommendation on box (Fiji B&W still has table) or sunny side rule f/16.

Noel

Noel
 
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