Developing One 35mm=one MF?

[peter k.]

Developing one 35mm with 36 exposures = same area of for one medium format roll of film.
Correct... ?
Don't do much color film developing, but fall is coming..

Just wanted to verify for Developer reuse.. as Arista C-41 is suggesting to add 8% to the process each time you do a new batch, but their considering that one is developing in a daylight tank, and doing two rolls of 35mm film each time, as they state ".. you just developed two rolls o film at 104*, multiply 3.5 (the developing time at 104*) by 1.08" for next two.

So if one is doing a mix, 35mm and MF, by my thinking, with a tank that holds only one MF, you could keep the same timing for the second roll of MF, or for another single 35mm.
Your thoughts..

 

[Rudeofus]

Generally yes, a roll of 35mm film has about the same surface area as a roll of 120 format roll film. Actual developer exhaustion depends on a number of factors, though:

1. If you do a prerinse, each dev run will increase developer dilution.
2. Different amount of exposure will lead to different exhaustion of developer.
3. Don't forget developer oxidation from air, both during dev run and in storage between dev runs.

AFAIK there exists no C-41 developer product which can be reused without replenishment AND which maintains process specs across all dev runs. Whatever you are going to do here is going to be some compromise (a good one IMHO, but nevertheless), so I would not worry too much about the exact time increase per roll or per dev run.

 

[StephenT]

Yes, 36 exp 35mm equals 12 exp 120 equals one 8x10.

 

[benjiboy]

No, if you look at the quantitys required on the bass of a Patterson developing tank the quantity of developer is greater for 120 film than 35mm.

 

[fdonadio]

No, if you look at the quantitys required on the bass of a Patterson developing tank the quantity of developer is greater for 120 film than 35mm.

Maybe because of the width of the films in question? I mean, they have the same area, but you have to use more chemistry to cover a wider roll, right? Also, two 135 reels are wider than one 120 reel.


Cheers,
Flavio

 

[peter k.]

Well ya got a point, but it's the film surface, that the developer is working on, not how much is used to cover it.
You could fill the tank full each time, and my thought it would make no difference, as the strength is depleted by what it develops.

 

[fdonadio]

Well ya got a point, but it's the film surface, that the developer is working on, not how much is used to cover it.
You could fill the tank full each time, and my thought it would make no difference, as the strength is depleted by what it develops.

For sure, but what I meant is that Paterson recommends more developer because of the coverage, not because of the depletion.


Cheers,
Flavio

 

[peter k.]

yes so does my tank, but what I'm referring to here, and focusing on, is not the amount of the developer used, but its depletion! That's why you have to increase the time by 8% after you do two rolls, according to the instructions.
Yes, to develop MF you have to have more quantity of developer, but what it is developing is the same amount of area, as a roll of 35mm.
So my understanding, is that the depletion of the developer would be equal.

 

[fdonadio]

Peter,

Understood and agreed. I was just trying to "invalidate" benjiboy's argument.

Every Kodak literature I've seen considers one roll of 135/36 the same as a roll of 120 — for developer/fixer depletion purposes.


Cheers,
Flavio

 

[mklw1954]

Of course more volume is needed to cover the 120 film - 14 oz. for 120 film vs. 8 oz. for 135 film (using stainless reels), but both films are 80 sq. in. so each counts as one roll when considering the capacity of the developer used up.