newbie question for B&W developer

Right now I use Ilford Ilfosol 3, and ilford stop bath and rapid fixer. The instruction manual only tells the capacity in terms of 135mm films. However, I would like to know its capacity in 120 films. How to convert them?( 1 125mm = 1 120mm) ??? Many Thanks.

36 frame 35mm equals 1 roll of 120. Basically the same square inches of film.

Usually depends on the size of the tank, but as a general guide using the figures on the bottom of my jobo tank.

135 10Oz / 290ml (round up to 300ml)
120 17.5Oz / 500ml

so to scale up multiply your 135 figures by 500/300, or 1.67 times more liquid needed for a 120 film

Are you asking about capacity as in how many rolls can be processed in a given quantity of chemistry? If so, Nick's answer is correct. If, however, you are asking about the volume of chemistry required by your developing tank, the easiest way to check is to assemble the tank and reel, put in enough water to cover the reel, but still leave some air above, and then measure the amount of water you used.

This is assuming you are using inversion agitation.

Hope this helps.

Matt

P.S. don't forget to dry the reel and tank afterwards

Nick and Aurum have answered two different questions. I suspect that jzhu was asking the question that Nick answered, but I'm not positive of that.

Most photochemicals have a certain capacity, in terms of square inches (or square centimeters, or whatever) of film or paper that can be processed per unit volume. By this measure, as Nick says, a 36-exposure roll of 35mm film is roughly equal to a roll of 120 film in surface area, and so either type of film will exhaust your fixer (or whatever) equally. This issue is most important when the photochemical is re-used, although it can also be important for single-use items when they're fairly dilute -- you might need a particular volume of developer to fully develop a roll of film, and if that volume is more than the minimum required to cover the film in the developing tank, you may need to use extra developer.

Aurum's point answers the issue I've just raised -- how much solution do you need to cover a roll? For this, 35mm and 120 are seldom equivalent, unless you process two rolls at once and, for 120 film, fit two rolls on one reel. Most tanks require 250-350ml of solution for a roll of 35mm, but about 500ml for a 120 roll. This determines the cost of single-use solutions, unless they're dilute enough that you need to add more than the tank's minimum. Most plastic tanks have their recommended minimum solution volumes stamped on them. For stainless steel tanks, measure to be sure what you need.

Thanks all. Nick answered my question.
Thanks for srs5694's full explanation.
I am using a metal tank that holds approx. 500ml liquid. I need about 400ml to cover my 120 film. I was wondering how much 120 films can I process using 400ml working strength developer. If 1 135mm(36 frame) = 1 120 film, I can calculate the number base on the number given in the user guide.

MattKing said:

Are you asking about capacity as in how many rolls can be processed in a given quantity of chemistry? If so, Nick's answer is correct. If, however, you are asking about the volume of chemistry required by your developing tank, the easiest way to check is to assemble the tank and reel, put in enough water to cover the reel, but still leave some air above, and then measure the amount of water you used.

This is assuming you are using inversion agitation.

Hope this helps.

Matt

P.S. don't forget to dry the reel and tank afterwards

Click to expand...

How do I dry them? I just rinse them with water, and hang dry. Is that good enough?

jzhu said:

How do I dry them? I just rinse them with water, and hang dry. Is that good enough?

Click to expand...

***********8

I was taught to use a vegetable bristle brush and Bon Ami cleaner, Zud, or Bar Keeper's Friend and scrub out the reel and tank. While doing that I run hot water through the tank lid. I rinse everything well, then I hang the reels on a peg board, and put the tanks upended with the lip just off the work surface to air dry.

what's Bon Ami cleaner?

Aurum said:

Usually depends on the size of the tank, but as a general
guide using the figures on the bottom of my jobo tank.

135 10Oz / 290ml (round up to 300ml)
120 17.5Oz / 500ml

so to scale up multiply your 135 figures by 500/300,
or 1.67 times more liquid needed for a 120 film

Click to expand...

So much for the solution volume needed. The amount of
developer needed for a 120 is the same as is needed for
one 135mm 36 exposure. Using the same amount for
the 120 will result in a more dilute solution. Allow
more time for development. Dan

jzhu said:

Right now I use Ilford Ilfosol 3, and ilford stop bath and rapid fixer. The instruction manual only tells the capacity in terms of 135mm films. However, I would like to know its capacity in 120 films. How to convert them?( 1 125mm = 1 120mm) ??? Many Thanks.

Click to expand...

A single 135-36 cassette, a single 120 roll, 4 4x5 sheets, and 1 8x10 sheet are each approximately 80 square inches of film. A single 220 roll is double the length of a 120 roll and is approximately 160 square inches. Those are the numbers you need to know to figure the exhaustion rate of your developer.

jzhu said:

I am using a metal tank that holds approx. 500ml liquid. I need about 400ml to cover my 120 film. I was wondering how much 120 films can I process using 400ml working strength developer. If 1 135mm(36 frame) = 1 120 film, I can calculate the number base on the number given in the user guide.

Click to expand...

Most developers are used one-shot -- that is, you use them and then dump them. Thus, unless you're using your developer so dilute that 400ml won't process a roll of 120 film, you should be concerned mainly with just getting enough developer to cover the roll.

Fixers, OTOH, are generally re-used, so you need to be concerned with the capacity of the fixer, in terms of the amount of film you can fix per liter of fixer. A little math will reveal how many times you can re-use the fixer. Alternatively, you can use a clearing time test: Stick a small piece of film in the fixer and time how long it takes to clear. When the clearing time doubles compared to the time for fresh fixer, the fixer is exhausted. (Note that clearing times can vary from one film to another, so you must be familiar with the clearing times of all the films you use for testing.)

Thanks srs5694 for the extract comment. I though I can re-use developers as well. Maybe that's why I didn't found much information on reusing developers on Internet. Looks like I can only reuse the fixer. I have on idea about what the film will look like if it is not clear("fixed" another word). According to your comment, seems that I should take a little piece of film and put it in the fixer to figure out the best fix time for that film, is that right? Which should be done after developing and stop bath, right?

Thanks frank for the information. That gives me the idea for 4 x 5 films, which I may go for in the future.

jzhu said:

I though I can re-use developers as well. Maybe that's why I didn't found much information on reusing developers on Internet.

Click to expand...

Most developers can be re-used, but this is generally done at lower dilutions (often at stock dilution), and it works best for fairly high-volume operations, in conjunction with replenishment. This sort of use was once common for big photofinishers, and I suppose it's still common for commercial color photofinishers. There may still be a few B&W photofinishers who do enough volume to make it worthwhile, but they must be fairly rare.

Instead of re-using developers, most hobbyists use them at greater dilutions (say, 1+1, 1+2, or 1+3 for D-76 or XTOL). This reduces costs, much as re-using does, but it's less hassle and it produces more consistent results when you don't run dozens or hundreds of rolls a day.

You mentioned Ilfosol 3 in your first post. I'm not very familiar with that developer, so I don't know if Ilford even has data on re-using it. You mentioned that you've found capacity data for it. You might do some math to see how much volume that works out to. For instance, if it says "8 rolls per liter at x+y dilution," then you probably need at least 125ml to develop a roll, and you'll be fine with a tank that requires 400ml. If it says "2 rolls per liter at x+y dilution," then you might want to boost the volume you use to 500ml.

Looks like I can only reuse the fixer. I have on idea about what the film will look like if it is not clear("fixed" another word). According to your comment, seems that I should take a little piece of film and put it in the fixer to figure out the best fix time for that film, is that right?

Click to expand...

Yes.

Which should be done after developing and stop bath, right?

Click to expand...

No, you do this before you develop the film -- you cut off a small amount when you load the developing tank, set it aside, and before you begin processing you dunk it in fixer. You can do this in room light. Without developing the film, this will result in a completely cleared piece of film, assuming the fixer works at all. Double the clearing time is your fixing time. (Some people say three times the clearing time, either for all films or just for T-grain films.) I use double (or triple for T-grain films) the clearing time or the manufacturer's recommended time, whichever is greater. This is usually the manufacturer's recommended time, except for a few films when the fixer is nearing exhaustion.

FWIW, getting a spare scrap of film is easy with 35mm -- you just use the leader that you cut off to load most tanks, so there's no risk of cutting into your actual photos. With MF, you can also cut off a centimeter or so from the start or end of the roll. Depending on your camera, there's some risk of cutting into your image when you do this. Alternatively, you could sacrifice a roll to use for test snips like this, but it should be the same type of film you're processing, since clearing/fixing times vary between brands and types of film.