I would suggest increasing your agitation somewhat - how about four gentle cycles each minute or two gentle cycles each 30 seconds?
Originally Posted by Tofek
That will help remove local developer exhaustion from the list of potential causes for your low contrast negatives.
An inaccurate thermometer is another likely cause. As long as your thermometer is consistent, you can (within limits) compensate for potential inaccuracy by increasing development time. If the thermometer is inconsistent it needs to be replaced.
I'm not exactly sure I understand what you are saying with respect to Zone 0 exposure, but if you are wanting to increase the exposure, you need to decrease the Exposure Index ("EI") set on your meter.
The thermometer should be acurate, it isn't old and is quite precise (0,2°C).
As for agitation, as I said I prefer to change time not only for the habit of agitation, but also because the grain will be bigger with more agitation (you'll tell me not to use Rodinal if I want small grain... ;) ).
Concerning the zone 0. I made the exposure test : meter a wall (zone V) and close the diaphragm 5 stops to get to zone 0. If correctly exposed, there shouldn't be fog, if I understood well. But there is some, in my case. Which means that I over expose the negative when setting my meter at 100ASA. That's why I was talking about increasing the EI.
With thermometers, precision and accuracy are two separate issues. :D
Originally Posted by Tofek
It could be precise, but not calibrated properly.
And with respect to agitation and Rodinal, I think you will find that if you keep the cycles gentle you will continue to minimize grain.
Unless you have a light leak, the fog comes from the film and development, not exposure. Increasing the exposure will raise your shadow detail above the fog, whereas reducing exposure will cause more detail to be obscured by fog.
But I don't get it then...I thought that zone 0 should have zero fog, zero silver reduced., as it is said in Barnbaum's book ?
No. There is always a minimum silver density. Image density is the net density above the film base+fog density.
And if your prints are muddy, check your safelight, and check your darkrooom and enlarger for light leaks. Safelights are not always safe.
Originally Posted by Michael R 1974
You can do a simple test by simply turning off the lights and check for light leaks. If there are any, plug them, until your darkroom is safe.
Then make a print without the safelight on. If the prints still look the same, then you don't have a light leak problem.
All the advice pre-supposes that your negs have shadow detail where you want and expect it of course. If not, then increase exposure too.
I would suggest that having to print on grade 5, or any high magenta value for multigrade is not a good idea. Why not try and adjust your camera exposure and negative development time/temperature until you can consistently print on grade 2 or with zero filtration on multigrade?
You already did the test ["I usually print on Grade 5"] so just increase film development by 25% to give you some more leeway so most images print on grade 2 or 3.
Explanation: Development time tests are to save time and money. Otherwise you need to do experimentation by shooting typical scenes and, processing negatives without knowing if they will be printable on the commonly available paper grades. Since you have already done that experiment and determined your negatives print on grade 5, there is no need to go backwards from there.
I wanted to do the tests anyway, to understand a little more what's happening, why the contrast is low, how much should I increase the time etc. But I see your point.
For the fog however, I don't see why there should be more fog on a field exposed as zone 0 than on a field which received no exposure ( lens cap on ) ? That's the case in my test, and it proves that the light meter didn't give me zone 0 exposure (respectively zone V) but a little more (overexposure). Isn't that correct ? I'm trying to understand...
Thanks for the replies guys ;)