Logical explanations to the different behavior of the same film in different format?

[tkamiya]

I wonder if someone can offer me a logical explanations for this...

I shoot both in 35mm and 120 format. Using the same film (Tmax400) with same EI, using the same developer and dilution, agitation schedule and everything else, the best result (to my liking) can be obtained using different timing.

For example, using Tmax400 with XTOL 1:1 with 5 initial agitation and 2 subsequent every 30 seconds:

135 film comes out the best at -15% reduction in dev time. If I used the time by chart, it comes out way too contrasty no mater the lighting condition. I can go up to -10% if the scene was low in contrast but not any longer than that. -20% will result in dull looking negative.

120 film come out the best from spec time to -15%. -10% is always successful and low contrast scene will benefit from development at spec time.

My process is very exacting. I maintain temperature at +/- 1F and use water bath. I did my best to maintain everything the same every time. Despite of this, the same film in 135 format seems very temperamental where as 120 format is forgiving. Oh, I use condenser type enlarger.

Why, why, WHY??

 

[Sirius Glass]

Hint: Try following the manufacturer's instructions for starters.

The film base can be and often is a different thickness. 35mm film is self supporting; 120 is supported by paper, the paper blocks any light behind the film and the paper can absorb light passing through the film; 4x5 film is even thicker than either 35mm or 120 film. The anti-halation coating maybe different.

Steve

 

[tkamiya]

Steve,

I did start with the manufacturer's instructions. How else one would start that? So far, my best result is obtained using a method as outlined above. I'm looking for a logical explanations for what I'm observing.

 

[Anon Ymous]

Hint: Try following the manufacturer's instructions for starters. ...

Steve, the manufacturer clearly states that the proposed times are for diffusion enlargers and those using condensers may need to reduce contrast.

 

[RalphLambrecht]

... Why, why, WHY??

Try to come up with a list of all the difference between the two films and all the factors that influence negative density. That's where your answer is.

Go for it, make a list of the differences, not what you've done to make it the same.

 

[MattKing]

Hint: size of film and reels, and the resulting effect on agitation.

 

[RalphLambrecht]

Hint: size of film and reels, and the resulting effect on agitation.

The substrates of these films are different. That could be the reason alone.

Another difference between these formats are that they are exposed in different cameras and with different lenses. What about lens and cameras flare? They can have a major influence on film exposure and negative contrast.

Also, if internal lightmeters are used, they could make a difference too.

 

[MattKing]

I could have sworn I posted "Hint about one of the differences: size of ..."

And it occurs to me that Ralph's second listed difference could be productively referred to in the "Medium Format Cameras That Are Compatible With 35mm Film" thread.

 

[ic-racer]

Have you determined that your processing is consistent between the two film formats by testing with a step wedge control strip? If they are the same then the differences in your negatives are because of different cameras.

 

[winger]

Is it possible that the shutter in one camera isn't quite as exact as the other? Or both are off just a little?

 

[2F/2F]

There are many things that could cause this, and honestly, I am surprised that there is as little difference as there is (10 percent, I gathered). In order for a roll of 120 to be covered, it requires twice as much developer solution as it does with a roll of 35mm. Not only will the amount of developer per surface area unit of film be twice as great with the 120 film, but agitation will be different, with 35mm being not only narrower and thinner, but also being spaced more closely together. I would think that this would cause significant differences in the effect that agitation has. Then, there is a whole list. They are shot in different cameras, with different lenses. The bases are of different thickness. There may be slight differences in the emulsions as well.

I also question your testing and analysis quite a bit, since the percentages that you describe as making a huge difference should not do so at all. A difference of 5 percent in time should not make the difference between a negative that is just right and a negative that is far too flat, nor should a 15 percent overdevelopment result in terribly contrasty negatives. These oddities make me think that you are not using a controlled lighting situation with a known and fixed luminance range to analyze your development.

I suggest doing controlled tests with an object of fixed luminance range. Shoot something like a MacBeth chart in a controlled environment with repeatable lighting, such as electronic flash. Barring that, make different exposures of a grey card, using your diaphragm to change exposure. Develop the films in the same tank and see if it makes a difference. If at all possible run the 35mm through the medium format camera to make the tests.

My guess is that if, all things being equalized (i.e. shutter, lens, etc.), the difference still exists, that agitation is the number one culprit. The developer rushing more quickly over the surface of a roll of tightly-spaced 35mm film than it does over the surface of a more-widely-spaced 120 film makes sense.

 

[jeffreyg]

I would try a standardized test with controlled light, framing a gray card, the same chemistry etc. to determine the effective ISO for the film used in each camera as 2F/2F says. That will take into account differences in your equipment but I would use 120 film in the MF camera. My guess is that there is more difference between your equipment than the film manufacturer's suggested dev. times which are just guides anyways.

Jeff

http://jeffreyglasser.com/

 

[RalphLambrecht]

... In order for a roll of 120 to be covered, it requires twice as much developer solution as it does with a roll of 35mm. ...

Why is that? I thought they are both about 80 square inches.

 

[pentaxuser]

Ralph I assume the poster is referring to the size of the tank which is bigger because of the size of the reel so its a liquid volume thing not a developer strength thing. My 35mm Jobo is OK with 240mls but a 120 tank requires 485mls to cover the film.

pentaxuser

 

[RalphLambrecht]

Ralph I assume the poster is referring to the size of the tank which is bigger because of the size of the reel so its a liquid volume thing not a developer strength thing. My 35mm Jobo is OK with 240mls but a 120 tank requires 485mls to cover the film.

pentaxuser

OK, I just happen to use the same tank for both.

 

[Q.G.]

OK, I just happen to use the same tank for both.

So do i, and it still takes different amount of fluid to cover both.
(Though one could of course always use enough to cover the tallest film. Seems a waste though.)

 

[pentaxuser]

In effect and if you stick to Ilford's recommendation for DDX dilution you automatically waste developer when developing 1x 120 film. If we assume a 120 is the same surface area as 35mm then 485mls in a 120 Jobo tank will do 2 x 35mm but only 1 x 120( but see below). The only way to equalize usage of developer would be to do 120 at say 1+8 but if 1+8 is OK for a 120 then it is OK for a 35mm and indeed some do use 1+9. However at 1+8/9, 2x35mm is still more economical than 1x120. As I see it there is no way round the fact that developing 1x120 film is more expensive in developer use and the only way to equalize cost is to do 2x120 each time on a 120 reel with a divider.

If you only take 1x120 as opposed to 2x120 and need to develop it that day then you waste developer.

pentaxuser

 

[RalphLambrecht]

So do i, and it still takes different amount of fluid to cover both. ...

You must be talking stand or inversion development. It doesn't take a different amount with rotation development.
And, it's a waste to do anything else!

 

[Doremus Scudder]

For the OP:

Why, why, why has been more than adequately explained above.

The bottom line is: Variations like this are to be expected. Quit trying to find a way to reconcile them, rather happily calibrate your 120 and 135 film (and accompanying cameras, metering systems, shutters, developing tanks etc., etc.) to different developing times to get the results you want.

Best,

Doremus Scudder
www.DoremusScudder.com

 

[2F/2F]

Why is that? I thought they are both about 80 square inches.

Are they both developed laid out flat, like a piece of 8x10 film in a tray?

 

[RalphLambrecht]

Are they both developed laid out flat, like a piece of 8x10 film in a tray?

No, but I still use the same amount to cover both formats. What are you doing differently?

 

[Sirius Glass]

135-36 = 80 square inches of surface
120 = 80 square inches of surface
four 4x5 = 80 square inches of surface

 

[Q.G.]

You must be talking stand or inversion development. It doesn't take a different amount with rotation development.
And, it's a waste to do anything else!

Stand and inversion (i let the tank stand inbetween inversions )

Yes, rotation development...
Would you then not need less fluid for a 120 film than for 135 film?
In my spools, 120 film doesn't reach all the way to the core of the spool (stays in the outer grooves) while 135 film does. So the fluid level would not have to reach all the way up to the core to reach all of the 120 film, while it would to reach all of the 135 film.
Just wondering.

 

[RalphLambrecht]

... Would you then not need less fluid for a 120 film than for 135 film?
In my spools, 120 film doesn't reach all the way to the core of the spool (stays in the outer grooves) while 135 film does. So the fluid level would not have to reach all the way up to the core to reach all of the 120 film, while it would to reach all of the 135 film.
Just wondering.

No, same amount for both. I most often use a Jobo UniTank 1520 which specifies 240 ml for rotation when developing two 135 or 120 rolls of film. However, I usually use 300 ml in order to not run out of developer activity.

 

[ic-racer]

Ralph I assume the poster is referring to the size of the tank which is bigger because of the size of the reel so its a liquid volume thing not a developer strength thing. My 35mm Jobo is OK with 240mls but a 120 tank requires 485mls to cover the film.

pentaxuser

1520 tank requires 240ml to cover 220 film. If you only load a single 120 on the outer portion of the spiral, then your volume requirement is less.