Rodinal FP4 trouble

Hope some one can give some good advise. I am calibrating FP4/rodinal to forte polygrade V/dektol 2:1. The speed test came out at 100asa according to maximum black with my enlarger(4x5). I've been trying to get the zone8 value in the ballpark but so far have struck out. I've tried rodinal at 25:1 for 7min and 50:1 at 11min. Both films were developed in a tray one at a time with a total of 500ml so that's 10ml+500ml and 20ml+500ml to give the dilutions. I used exactly the same agitation cycle and boom! Both came out the same density! Any clues? Thanks

What you did would be expected to produce similar densities. You developed longer in a more dilute developer and got similar contrast. You don't say which way you want to go, but if you want less contrast, keep the same time with greater dilution or go with shorter times at the same dilution. You can also decrease agitation to lower contrast.

If you need greater contrast you should increase time, decrease dilution rates, or agitate more.

Lee

Dunno, but you're spoiling a lot of Rodinal to make your 1+25 dillution! I use Rodinal mainly because it's an economy class developer.

I can only give you my Rodinal / FP4 combo, but I don't think you can compare the data.
- semi stand in a slosher tray, 4 4x5" negs at a time (or 2 5x7")
- 1+75 dillution
- about 1 hour
- agitate first 30", than 30" at 15' and 30' and leave it for the rest of the time.

Don't take my word for it: I'm not that kind of calibrating and testing guy but my negs come out fine with good shadows and highlights. It just takes up more time to develop.

@Lee:

I would not increase agitation. I did test that once with short (rollfilm-alike) times in dillutions of 1+25 and 1+50 and the sheets came out horrible and unusable.

G

argus said:

@Lee:

I would not increase agitation. I did test that once with short (rollfilm-alike) times in dillutions of 1+25 and 1+50 and the sheets came out horrible and unusable.

G

Click to expand...

Understood. I was just trying to give more generalized guidelines on how to achieve increased or decreased contrast, since it appeared that Ron(?) was making simultaneous adjustments (dilution and time) that worked in opposition to each other where contrast is concerned. I was also trying to get my son out the door to a doctor's appointment and was a little brief. I've never used dilutions of 1+25, but almost always use 1+100.

Lee

No problem Lee,

as you pointed out, changing development 2 parameters at the same moment is always bad. You'll never know what adjustment is responsable for a certain change in the result.

I hope your son is OK.

G