Different films; same dev time.

[DylanCraver]

Say I've got two rolls of film here, from different companies with different emulsions and different speeds. However when pushed or pulled to a certain EI and coincidentally having the same development times.

Would it be safe to process both films together in order to not waste chemicals and spend less time developing film?

Thanks,
Dylan

 

[DarkroomExperimente]

I've done that before without a problem

 

[DylanCraver]

Awesome, that should save me some time.

Thanks for the quick reply!

--Dylan

 

[BobNewYork]

Yup - no problem. I do it all the time. Beware of falling into the "near enough" trap that I did some years ago though. Personally, I find film development akin to watching grass grow and I did one combined run where two film times differed by two minutes. I, of course, split the difference and spent more time and money on printing and materials, (not to mention the mental health effects!) than I'd saved on the film development. A cautionary tale..........

 

[Photo Engineer]

Bob has a good point, however it depends on the film. I have had the same situation where the films in question differed by 2 minutes, so I split the time, and can hardly see the difference in the two films regarding their normal behavior.

PE

 

[Steve Smith]

I did exactly that last weekend. In my case there was only 30 seconds difference so I used the longer time.


Steve.

 

[Akki14]

Use diafine and the EIs recommended on the box for various films. Then you can have 3minutes in solution A and 3 minutes in solution B and be done with it I'm impatient with developing times too, especially if they drag on for 20 minutes.

 

[Rolleijoe]

That's my regular every-day way of processing film. When I shoot, I go for a particular DoF and set according to that, and adjust only my shutter speed. I regularly shoot anything from Ortho25 to Neopan 1600 and process them all together, and have never had a problem.

YMMV
Rolleijoe

 

[nworth]

I haven't had the situation come up lately, but I don't see why it wouldn't work, at least for most films. Some modern films have some strange components which dissolve in the developer, however. I'm thinking of the red dye in Kodak TMY right now, but there may be others. I'm not sure how these would affect the other roll.

 

[Photo Engineer]

Something you all should think about....

All B&W film sent to a photofinsiher or pro lab will get one development time in one developer. They don't adjust! Now, I will hasten to add that some pro labs will adjust for a special price, but on average, there is one time and one developer.

PE

 

[PHOTOTONE]

IF you have a darkroom, you can develop different films in the same tank at the same time, for different developing times. Here is what you do. You fill the tank with developer and leave it in the sink. You then load your film, keeping track of what film is what. When you start, you put the film needing the longest time in the tank, put on the lid, and start the timer..
Lets say you have a film that requires 10 minutes developing and one that requires 8 minutes developing. In the dark, with your glow-in-the-dark timer you watch the time and after 2 minutes you open the tank and plop in the 8 minute film. If then, all the film is in the tank, you can turn on the light and proceed normally.

 

[Photo Engineer]

The problem with that one is that film requires an initial hard agitation to get the air bubbles knocked loose, or it needs a prewet. I've done that, but it can be difficult to achieve good uniformity. The times I've done it were for experiements where only the sensitometric scale was important, not picture quality.

So, for practical purposes, the top reel or last one to go in, gets an initial agitation that is needed and you hope that the one underneath is not over agitated. Myself, I did it with film racks in a large tank and kept the racks widely spaced to prevent this type of problem. If needed, I also held the second film in a prewet for a minute before development.

PE

 

[PHOTOTONE]

To avoid over-agitation and over-development of the first roll in, you just cut back a tad on the development of the first roll in, thus to compensate for the next roll in, which also gets a bit more vigorous agitation cycle for the first agitation cycle after you drop the film in.

Or as PE says, you could plop all the reels of film in a water presoak and transfer them as required to the developing tank.

 

[Ian Grant]

A far better alternative is to use 2 or 3 developing tanks.

Ian