Rodinal FP4

Am doing film testing trying to get myself on track. with FP4 , rodinal, forte polygrade V and dektol 2:1. My speed tests indicate 100 asa is good but am having a hell of a time getting a zone 8 developement time. I expose a full sheet to Zone 8 using a diffusion glass pointed at the sky(much like Ansel Adams pre-exposure recommendations) metering directly in front of the lens then setting my exposure for zone 8. I just developed my last 2 shots; one at 25:1 for 7 min and one at 50:1 for 11 minutes...................they both came out almost exactly the same around 1.6 measured on my densitometer. I don't use the densitometer to calibrate just as a measuring device to see where I am. I know I need a a density of around 1.25 to get zone8. any thoughts as to what I could be doing wrong? I did develope just one film at a time in a tray carefully measured the temp at 68deg one with 20ml per 500ml and one with 10ml per 500 ml. Is it that I have developed them singly? I ususally develope4 at a time ala slosher.

I also checked my meter against my nikon F3 and the agree within less than 1/3 stop.

Hello:

Is this 4x5 film or larger? Try doubling the volume and 12-14 min at 1:50. Your 1:25 times might be increased by 1-2min.

yours
Frank Johnston

Hello: I should read more carefully- try 1:75 and 1:100 dilutions.

yours
Frank

Sounds like you may be beneath the radar as to the minimum amount of Rodinal in your solution.

I looked at so0me marvelous 1:100 Rodinal negs that Richard Boulware produced last weekend with T Max 100. He developed them in tanks with conventional hangers (plenty of solution here is the key) and he was commenting that about 14-15 minutes was his standard time at I believe 68 degrees.

Check the Rodinal literature to see what they recommend as far as minimums per sheet. Let us know what you find out.

Cheers!

I always assumed that if one were below the minimum amount of required developer that you'd experience uneven developement or thin negatives but I am not an expert. Anyone know the answer to this one? Thanks need all the help i can get. Ron

If you are trying to learn something change time or dilution, not both at the same time.

Hello Ron,
I think that processing your film one sheet at a time could easily result in greater density than expected. It would be hard to provide for the exact same amount of agitation that you would get with four sheets at a time--assuming by "slosher" that you mean in a tray. When doing film tests you have to do everything the same way as you plan to develop your regular film, otherwise you are likely to get different results.

You will get thin negatives if you don't have enough concentrate in the solution. Use the appropriate amount of concentrate for the amount of film but increase the amount of water to get more dilution.

You are likely to get uneven develpment if your development time is too short. For me, seven minutes is the shortest amount of time that I would want to use (but some people do successfully use shorter times).

I don't understand the usefullness of processing for a zone eight exposure. I think that it would be much more effective if you meter and expose for a Zone Three (assuming that you already know your EI) on around four or five negatives and then adjust development, either time or dilution (development time is most easily used) but not both as Aaron said, to get a Zone eight density on your film. This would give you a normal development plus give you some information on what expansion and contraction look like.

Also, since you have the densitometer why don't you use it to calibrate?

Thanks David, your information is very helpful. i've just exposed four more films and plan to process them together at varying times. I try not to use the densitometer too much for fear of getting too involved with sensitometry. The only reason I have one is that it is a tool that I use at my day job(medical x-ray repair) but i'll admit it can be a very useful tool.