Nominal EI for B&W Film

Snapshot

Member
Joined
Jan 10, 2007
Messages
913
Location
Toronto, Ont
Format
Multi Format
Hi All,

I have traditionally been exposing film at their nominally rated EI (e.g. 100 for 100 ISO rated film). However, I have considered exposing film 1/3 of a stop slower. For example, I want to expose T-Max 100 or APX 100 at EI 80 for improved tones. Will this 1/3 stop help with reducing (slightly) grain size as well? Are there any other consderations that I should give thought to. Any input would be appreciated.

Regards,

Anthony
 

brian steinberger

Subscriber
Joined
Jan 5, 2007
Messages
3,015
Location
Pennsylvania
Format
Med. Format RF
How are you printing? Are you developing the film yourself?

If you are printing on silver paper and developing yourself, then you need to run some film speed tests. Search the forum for film speed tests.

Shooting TMX at 80 instead of 100 is going to give you 1/3 stop more shadow detail. Whether or not you need this decrease in speed depends on your developer, developer dilution, your thermometer, your meter, your lenses, etc.

My suggestion is to run a film speed test to find your own personal EI. Again, there are many threads on here discussing film speed tests. The basic theory is exposure for the shadows and develop for the highlights. If you're not getting adequate shadow detail in your negatives, lower your EI. If your highlights are burnt out decrease development time. And BTW, 1/3 of a stop increase in exposure has nothing to do with grain.
 

Roger Hicks

Member
Joined
May 17, 2006
Messages
4,895
Location
Northern Aqu
Format
35mm RF
Dear Anthony,

Any increase in exposure will increase grain size (except with chromogenic films) and reduce sharpness. The difference at 1/3 stop is unlikely to be noticeable. The difference at 1 stop will be noticeable.

You might care to take a look at the free module on ISO speeds in the Photo School at www.rogerandfrances.com.

Cheers,

R.
 

Amund

Member
Joined
Nov 18, 2004
Messages
902
Location
Oslo,Norway
Format
Multi Format
After doing the film and developer "song and dance", trying almost any film and developer out there, at many different EI`s, I`ve found using film at(or 1/3rd less) box speed with "modern" developers(XTOL, DDX, T-Max) gives me great and very printable negs pretty much every time. Go figure...
 
OP
OP

Snapshot

Member
Joined
Jan 10, 2007
Messages
913
Location
Toronto, Ont
Format
Multi Format
Currently, I'm developing T-Max with T-Max developer and I'm printing on Ilford RC papers using Ilford developers. I know when I was using Ilford's XP2 Super I didn't see any grain increase when I overexposed. I will experiment with 1/3 stop and 1 stop exposures and see what happens. I do want to see additional shadow details but not at the expense of sacrificing significant sharpness and enlarging grain.
 

Roger Hicks

Member
Joined
May 17, 2006
Messages
4,895
Location
Northern Aqu
Format
35mm RF

As I said, chromogenics such as Ilford's XP2 Super give FINER grain when overexposed -- but both chromogenics and conventional films lose sharpness. The big question is what you regard as 'significant' in either bigger grain or reduced sharpness.

Cheers,

R.
 

Roger Hicks

Member
Joined
May 17, 2006
Messages
4,895
Location
Northern Aqu
Format
35mm RF

Dear Amund,

Of course you are right, but then, you seem to belong to that school of photographers who believes that the purpose of taking pictures is to get photographs, not to purify the soul through suffering.

At box speed, you are over-exposing (as against the true ISO in DD-X, the most speed-increasing of the devs you mention) by around 2/3 stop, which most people agree will give prettier tonality. Likewise if you drop 1/3 stop and use Xtol (I don't know what true speeds do in T-Max).

Cheers,

R.
 

Peter De Smidt

Member
Joined
Oct 20, 2004
Messages
1,093
Location
Fond du Lac, WI
Format
Multi Format
I too will recommend personal testing. It really doesn't need to be very difficult. Box speed has never given me zone I at greater than .1 above film base plus fog, but this depends on one's meter, technique... In my case, I expose 4x5 TMX100 at EI 64. That's not overexposure, as it's my personal EI for normal contrast with my film. Regarding speed increasing developers, I've not found them to give more than a true 1/3 stop increase over good old D76.
 

Xmas

Member
Joined
Sep 4, 2006
Messages
6,398
Location
UK
Format
35mm RF
When I use nominal speeds and meter carefully I find the shadow detail is frequently missing, one has either to meter even more carefully, or use more safety factor. The safety factor in the nominal was reduced by about a stop in '61 or so the film did not change, the shadows just got thinner.

The tabular 100s have pretty good grain how big are you enlarging?

Noel
 

Roger Hicks

Member
Joined
May 17, 2006
Messages
4,895
Location
Northern Aqu
Format
35mm RF
Xmas said:
When I The safety factor in the nominal was reduced by about a stop in '61 or so the film did not change, the shadows just got thinner.
Noel
Click to expand...

Dear Noel,

An excellent point. In the late 50s, many photographers complained than films were under-rated and were 'really' a stop faster. Today they complain that they are 'really' a stop slower. The manufacturers can't win!

How do you meter? I find that with spot metering of the shadows the details is ALWAYS there at the ISO speed, but I prefer the tonality with an extra 1/3 stop, 1/2 stop or even 2/3 stop extra exposure.

Cheers,

R.
 

Paul Howell

Subscriber
Joined
Dec 23, 2004
Messages
9,835
Location
Scottsdale Az
Format
Multi Format
Over the weekend I reread (last read 30 years ago) Andreas Fininger the Darkroom Vol 1. He stated that with a properly exposed you should be able to read newprint though the highlight and see details in the shadows. Last night I shot a roll of Forma 400 120 6X9 at 1/2 stops, developed in Ansco 17 a D 76 type developer and then found the frame where I could read the highlights and see details in the shadows was at 320-, it printed almost perfectly, the same as negatives that I spent hours and even days testing. I have not had time to shoot a roll in the real world. But I think this is the least complicated means that I have ever used to find a working film speed.
 

Jim Jones

Subscriber
Joined
Jan 16, 2006
Messages
3,740
Location
Chillicothe MO
Format
Multi Format
We should determine EI based on our own subjects, equipment, and preferences. Subjects without critical shadow detail can often be shot at the ISO rating with normal development. There's little need to increase exposure with older uncoated or single coated lenses beyond the point where flare masks shadow detail.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…