Confusing Fuji C-41 kit instructions

Hello!

Just got my Fuji C-41 kit. I've done C-41 before and know the process but I've not used this kit.

Fuji gives instructions how to increase developer time in small tanks and how many films can be processed total.

But, surprisingly, it says that you can process total 72 ISO 400-1600 135-36 films but only 32 ISO 400-1600 120 films. The surface area in these films is about the same. Is there really some difference between 120 and 135 films that could cause difference this big?

Here is a scan of the instructions:
Dead Link Removed

Some thing is off. 220 is the same number of rolls as 120. 12 shot 35mm is no different then 36.

The volume needed to cover a 120 reel is different.

Anon Ymous said:

The volume needed to cover a 120 reel is different.

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I just started with MF film and did the math too. It's even more skewed for my 4x5; 1 sheet or 12, takes a full liter.

Mark, the chemicals needed (as in chemical reactions) for any format are proportional to the surface of the film. In your case, 4 4x5 sheets should need the same amount of chemicals as a 135, 36exp film. Obviously, it doesn't take into account any differences about the needed volume to cover the reels. The critical detail in this case is how much you can reuse the chemicals. Whenever you agitate, you put air in the solution, which inevitably decreases their useful life. That might be an assumption from my part, but I can't think of anything else.

It simply takes a liter to get deep enough to sink the rack completely.

I do try to save up film for a processing day when I can make a liter and do 4 sheets and some 120 and some 35mm with the same liter.

Anon Ymous said:

Mark, the chemicals needed (as in chemical reactions) for any format are proportional to the surface of the film. In your case, 4 4x5 sheets should need the same amount of chemicals as a 135, 36exp film. Obviously, it doesn't take into account any differences about the needed volume to cover the reels. The critical detail in this case is how much you can reuse the chemicals. Whenever you agitate, you put air in the solution, which inevitably decreases their useful life. That might be an assumption from my part, but I can't think of anything else.

Click to expand...

Of course the idea behind this could be that 120 needs bigger tank for the same number of rolls, and the number of process runs with the same chemicals cannot be increased infinitely because of oxidation and contamination that always happens when the used chemicals are reused later. But still, max four process runs are recommended for 120, and for example 135-12 five process runs is possible, so this can't still be the only reason.

"8 rolls per process" for 5 liters is very low. In our Jobo rotary processing, there's 300 ml of processing solution in a tank accepting 120 (and even 220) films, that is 1/17th of 5 liters, and means that only a half 120 roll could be processed at a time if I followed these instructions. It's just silly. These instructions don't make a sense at all. Good thing that they are not a law that must be followed . I think I know how to use the kit after all.

hrst said:

"8 rolls per process" for 5 liters is very low. In our Jobo rotary processing, there's 300 ml of processing solution in a tank accepting 120 (and even 220) films, that is 1/17th of 5 liters, and means that only a half 120 roll could be processed at a time if I followed these instructions. It's just silly. These instructions don't make a sense at all. Good thing that they are not a law that must be followed . I think I know how to use the kit after all.

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I've used the Fujihunt 5 litre C-41 kit by mixing the concentrate required with water for Jobo capacity without issue.

Tom

The instructions sound right to me. I use Jobo tanks. The 35mm tank needs roughly half as much liquid as the 120 tank. I imagine this applies to most tanks so the Fuji-hunt kit instructions are about right. I'd expect use twice as much liquid for 120 as 35mm so I could do half as many 120 films as 35mm films. OK in a Jobo tank it is possible to put two 120 films on one reel and thus do the same amount of films as 35mm but Fuji- Hunt are basing its instructions on one film per reel.

If your tanks will only take one film per reel then it is likely that the amount of liquid to cover the 120 reel will be roughly twice as much as to cover a 35mm film. If you can fit two 120 films in the same tank then you can base the number of 120 films that the kit will process on this.

pentaxuser

pentaxuser, unfortunately that won't clarify anything.

First, the difference between 24 and 8 is three times, not two.

Second, 8 films per process per 5000 ml is very low in any case. Most tanks I've seen will process a 120 film with 300 ml, and that's 16 films for 5000 ml. It would be unbelievable that you couldn't process a 120 film with 300 ml solution but you could process almost two 135-36 films with it instead. Two 135-36 films even need larger tank.

Third, as you can see, with 100 ASA films, according to the instructions, you can make 16 120 films at a time with 5000 ml. Why not 400-1600 ASA films? I know, that faster films may require larger amount of active developer (and also are harder to bleach and fix), but why this does apply only to 120 films, not 135-36 that has about the same surface area? Also, in "ASA 100" 120 and 220 have the same "rolls per process" figure, as I expect, but different "Max no of rolls". These figures sound more realistic!

These questions are still unanswered. I can't but just wonder what's going on in their heads. Either the figures are out of this world or there really is some big coating difference between similar 120 and 135 films (that would cause doubling the replenishment flow ratios per surface area), but I really don't believe it...

In addition, it wouldn't make any sense that the chemical supplier would try to guess what kind of tanks people are using. If the datasheet says "max. no of rolls per process", I understand that it means it is some limit by the chemistry itself, which, however, can't be the case here as you definitely can process one 120 film with under 625 ml of any C41 chemistry.

hrst said:

... Most tanks I've seen will process a 120 film with 300 ml, and that's 16 films for 5000 ml...

Click to expand...

Are sure? 500ml sound fine, but 300?

Anon Ymous said:

Are sure? 500ml sound fine, but 300?

Click to expand...

Yeah, I'm talking about rotary processing which is quite common among color processing hobbyists. There's at least two series of Jobo tanks; the smaller ones and the larger ones. The larger one that accepts 120 films (or two 135-36) needs 280 or 290 ml solution IIRC. We have always used 330 ml just to be sure. The smaller ones need even less. With less than 500 ml, our tank can make two 120 films (on different spools) or three 135-36 IIRC at the same time.

AND, this can't be the issue since it says that 100 ASA 120 or even 220 films can be done 16 at a time per 5000 ml, and not 8.

To put the instructions again in another words, it says that you need 625 ml for one 120 roll but with the same amount (625 ml) you would make THREE 135-36 rolls. That won't make any sense even if we are talking about manually agitated tanks because even two 135-36 takes more solution than one 120.

I mailed Fuji if they could explain this .

Hrst,

I can process approx. 30+ rolls of 120 through a Fuji C-41 5 litre kit, one shot. (3 films per 470ml, say 480ml for safety. 480 x 10 = 4800ml)

Tom

Speculating even more ... Looking at the "Max No of rolls".

When looking at 135-36 films, the ratio between total number of 100-200 ASA and 400-1600 ASA is 96/72 = 1,33. So, 400-1600 ASA films would use the developer (and other solutions) 33% more quickly. Sounds about right.

Then, if we look at 120 films, the same ratio between 100-200 ASA and 400-1600 ASA becomes... 80/32 = 2,5!

This is just too silly .

Tom,

Yeah. That sounds about right for one-shot. With Fuji's instruction, you could do maximum 32 when using dev time compensation, and max 8 when doing one-shot. I'm not actually worried whether this works or not; I'm SURE that it will work just as you have said, but this piece of paper that has some very original and interesting figures on it is bugging me .