View Full Version : math, ugh!
back alley
04-04-2005, 18:12
ok, i'm about to develop a roll of film. i have been putting it off all weekend as i'm rusty. i have not souped a roll of film in years and for years before that it was all 120.
i left 35mm because i had trouble handling small film on the reel and in the darkroom. bad eyes and arthritis.
anyway, i have a roll of acros 100 and want to use rodinal for the first time.
massive dev chart says rated at 100 the recipe is 1+100 for 18 minutes.
ok so one roll needs 10 ounces of liquid, what the hell does that add up to at 1 to 100?
i have very small measuring cylinders and a syringe that measures in 10 cc increments (don't ask)
and while i have you here...most of my tanks are the really tall patterson jobbies for like 8 to 10 rolls. i used to work large.
but in the recesses of my darkroom i found an unused jobo single roll tank.
but i have never loaded a roll onto that reel. it looks kinda like the patterson reels but with a less pronounced ridge for starting the film. is that correct?
i think i'm gonna go out and buy a nice ss tank for one or 2 rolls...
back alley
04-04-2005, 18:18
does it have a lid?
joe
back alley
04-04-2005, 18:24
you got a deal my friend!
but can you tell me the formula for mixing rodinal 1+100 so it makes up 10 ounces?
joe
richard_l
04-04-2005, 18:50
1/10 oz to 10 oz will make 10.1 oz, close enough. 1/10 oz is about 3 cc (I think).
Right, very close to 30cc to the ounce. (29.5735)
Hi Joe, sounds like you're fixin' to have some fun! Let's see, 1:100 dilution would be like taking 100 oz of water and adding 1 oz of developer, ending up with 101 oz total. So if you need to use 10 oz of mix to cover one roll, that's 1/10 as much, so you only need 1/10 times as much Rodinal... that's 1/10 of an oz, right?
But I think there's a mininum amount of developer concentrate needed to work completely on one roll of film, isn't there? I don't see that info in the dev chart site. But 1/10 ounce of Rodinal may be insufficient to properly do the film. If for instance that minimum is .3 oz, then you should mix up 30 oz and use a 32 oz (four-roll stainless) tank to dev one roll of film. This is only needed with high dilutions... and almost sorry to raise this additional complication, but I'm guessing you might run into it here.
You'll want to find out if there's a minimum amount of Rodinal concentrate needed for one roll, use your syringe to squirt out that much in a big tank, then add 100 times that amount of water to make your total mix.
A one-roll Kindermann stainless tank holds 8 oz, a two-roll tank holds 16 oz.
back alley
04-04-2005, 19:09
the larger amounts were easier to figure for me than such a small amount.
i am (obviously) math challenged but have come to accept it.
doug, i hadn't thought about the prospect of needing a minimun amount of developer for it to work properly.
hhmmm...maybe i'll use ddx till i find that out for sure.
thanks guys,
joe
you got a deal my friend!
but can you tell me the formula for mixing rodinal 1+100 so it makes up 10 ounces?
joe
I quit trying to figure ratios out in ounces. Wayyy to hard. The Brooklyn school system sucked.
Anyway, in "general", either plastic or stainless steel tanks. A 2 reel tank is approximately 500ml. A 4 reel tank is approximately 1000ml.
4 reel tank @ 1:100 would be 10ml developer to 1000ml H2O
2 reel tank is half that or 5ml developer to 500ml H20.
Better to make a little more than too little. Let the excess pour out.
back alley
04-04-2005, 19:17
oh sure, bring ml into the equation! ;)
i was edumacated in queens btw!
joe
No sweat, ml is identical in size to cc, but seems to be getting overwhelmed by cc in usage. Like liters, a milliliter is a liquid measure of volume, where cc is non-liquid volume. So then why are syringes marked in cc??
back alley
04-04-2005, 20:05
well, for better or worse, my film is in the wash!
didn't have the nerve to look and see if there was anything on it yet.
and it's amazing how many small things die in one's measuring cylinders etc.
it HAS been a while...
joe
back alley
04-04-2005, 20:19
ok, the film is hanging to dry now and amazingly, there are actual images on it.
except those few frames where i thought i had the other body, with the tri-x in it, rated at 1600...yeah, those are a bit thin.
joe
Huw ? I can drop 1000 ml of liquid on my 2 reel AP tank. Probably US and EU sizes are different for tanks too :p
Hmmm, I've also got the 2 reel A&P tank (BTW, the A&P reels are the easiest to load of all the ones I know), but mine barely fits 800 ml, and there's no room left for air, which is bad, as the liquid won't be agitated well...
Roman
Oh, and BTW, the minimum of Rodinal per film recommended by Agfa is 10 ml, but there's a safety margin built in, you can go a bit lower at your own risk (this depends on kind of film - silver content, and also on the subjects photographed - very bright ones will require a lot of silver to be developed, needing more developer...)
Roman
I am sticking to the D76 stock solution diluted to 1:1 when I am ready. All this high math is too hard for me too.
Actually, my Diafine should be here today. Mix once and never worry again right?
I concur with Roman the AP reels are dirt easy to load, especially 120. Only in the last two years I've actually learnt to load 120 onto Paterson reels.
For all of you in the so-called 'developed world' learn the metric system. Everything works on multiples of 1, 10, 100, etc.
1000 ml = 1 litre
1000 meters = 1 kilometer
1000 grams = 1 kilogram
Does anyone see a pattern yet? Real easy huh?
Unlike the Imperial system that works on odd multiples like 8ths, 12ths and 16ths.
Queen Vic died ages ago, so did the British Empire, so should have inchs, ounces, feet and so forth.
Joe- Neopan in Rodinal at 1:100 is ok, but Neopan (regardless of ISO) really zings at 1:50. Or another way to look at it- 6mls of Rodinal, 294mls of water made upto 300mls of working solution for a single roll of 35mm in a Patterson tank.
Stu :)
Oh, and BTW, the minimum of Rodinal per film recommended by Agfa is 10 ml, but there's a safety margin built in, you can go a bit lower at your own risk (this depends on kind of film - silver content, and also on the subjects photographed - very bright ones will require a lot of silver to be developed, needing more developer...)
Roman
A fellow darkroomer who actually reads the factory recommendations...
WOW!
The only stuff I read from the manufacturers is the Density curve, Sharpness graph, Spectral sensitivity and I tend give toner instructions a quick glance at, before referring to Mr.Rudman's bible.
Stu :)
back alley
04-05-2005, 04:41
thanks for all the help, much appreciated.
will have to try rodinal at 1-50 in the future.
canada, btw, IS on the metric system, but i still have trouble converting.
joe
A fellow darkroomer who actually reads the factory recommendations...
WOW!
The only stuff I read from the manufacturers is the Density curve, Sharpness graph, Spectral sensitivity and I tend give toner instructions a quick glance at, before referring to Mr.Rudman's bible.
Stu :)
Actually, it never occured to me to read them until this subject was discussed very controversially on German B&W lab forums....
Roman
Btw, concerning Rudman's bible on toning: it is on sale now at Amazon, and rumor has it that there won't be a second edition - if you are into toning your own prints, this book is a must!
Roman
The _current_ recommendation for Rodinal is 10ml, but that number has been as low as 3 or 5 ml in the past. Do a search on pnet. At 3ml per roll, the stuff would last forever, which is probably why Agfa bumped up the recommendation. Of course, it'll also depend on what sort of wierd junk you have in your tap water.
Also, the concentration of Rodinal was changed over the years - you can still get the original stuff as Calbe R09 or Foma F09, and you have to dilue that 1+40 to get the same concentration as Agfa Rodinal 1+25. The Calbe stuff is slightly cheaper, but comes in really bad bottles, and since the Agfa stuff is also really cheap, I never bothered with the Calbe variety after I finished my first bottle.
Roman
Actually, it never occured to me to read them until this subject was discussed very controversially on German B&W lab forums....
Roman
Bayer NZ/Agfa was nice enough to send me their B&W bible for free.
The non-technical writing is, well very flowerly, PC and quite polite. However turn 2-3 pages over to the technical sections and words like "Must", "Have To", "Always", "This Is The Correct Time/Speed"...
I almost expected to read at the back of the book:
"If you do not follow this book to the letter, were sending someone around in a Tiger tank, schnell schnell schnell!"
Stu :)
Btw, concerning Rudman's bible on toning: it is on sale now at Amazon, and rumor has it that there won't be a second edition - if you are into toning your own prints, this book is a must!
Roman
Correct. Same applies to the lith printing book.
Which reminds me, I've got 10 litres worth stock lith developer I should use at some point...
Stu :)
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