is it my process or do 120 and sheet film require different exposure/developement?

[destroya]

I have started shooting 4x5 over the last few months and enjoying it. but I am having issues with differences between 120 film and sheet film. mainly its with delta 100. all my other films have no issues.

I have my EI and development worked out for all the films I use in 120. so I used that as a starting point for the same emulsion in 4x5 and all seem fine, maybe a little more contrast with the sheet film, but exposure/development seem very similar or similar enough to not make a big difference. but not so with delta 100. when I use my 120 settings (for lack of a better descriptive) all the sheets I shoot with all the lenses seem to be over exposed or over developed by at least 1 stop. I have only shot 12 sheets, but they are consistent. are there differences between ilford roll and sheet emulsions? I guess i have to do some testing, which is a drag, but i guess needed. for 120 I shoot at EI of 64 and develop in pyro-m 72 degrees for 15 minutes. 1 min initial agitation and then 10 seconds every 3 minutes.

so is it me or is there a difference?

thanks
john

 

[Alan9940]

FWIW, here are my notes for Delta 100:

1) For 4x5, I shoot it at EI 80 and develop in a Jobo Expert Drum, F76+ at 1:14 for 5 mins @ 75F on speed 4

2) For 120, I shoot it at EI 64 and develop in a small tank, F76+ at 1:9 for 5 1/2 mins @ 68F, continuous agitation for the first 30 secs, followed by 2 inversions every 30 secs thereafter.

This is all based on sensitometric testing, but since I don't use the same dilution of developer or the same developer temp I can't be certain how different, if at all, this really is.
Anyway, I hope this helps.

 

[138S]

Emulsion is the same, should work the same, if film is fresh.

Check your LF shutters, use a shutter tester.

 

[Ces1um]

My bet is that there's an issue with one of your two cameras and not your development technique.

 

[destroya]

well, i assume shutters are good because all my slide film and every color neg and B&W film comes out perfect. I guess Ill just do some testing and deal with it. its not like its a big deal, it was just a little surprise, thats all.

 

[138S]

Ill just do some testing and deal with it

You may use a roll film back in the rear of the view camera to check that both formats behave the same.

Personally I've never noticed a difference with fresh film.

 

[MattKing]

Roll film and sheet film and their associated camera systems can incorporate significantly different amounts of flare, and of halation.
And sheet film agitation is usually at least a bit different than roll film agitation.
All of those factors could lead to different EIs and contrast,
But I would suspect that the differences in lenses, apertures and shutters would be more important.

 

[removed account4]

have you noticed a difference between other films or is it just delta >
my guess is the LF shutter is a litttle slow so it over exposes
and the MF one is right on seeing your chromes are good with MF..
have fuN !
john

 

[Raghu Kuvempunagar]

To eliminate the differences in camera system and agitation playing a role, you might want to 1) use a roll film back on your 4x5 system as suggested by 138S and 2) use Taco method to develop 4x5 sheets in the daylight tank with identical agitation scheme.

 

[destroya]

just delta. I have used the same film in sheets and roll film with a roll film holder. I used velvia 50 to check, think it would show exposure differnces the most. they both came out the same. same with HP5 and FP4

again, its not a big deal, just one more thing to think about before tripping the shutter. I dont shoot delta in 120, I use tmax 100 or fp4. but the huge price difference in sheet film between kodak and ilford, I started shooting delta 100 and HP5. the HP5 comes out the same.

john