do i need to extend development time for tray development and, if so, by how much?

thanks!

BrianPhotog wrote:

do i need to extend development time for tray development and, if so, by how much? thanks!

When I process film in trays, I've found I need to shuffle the stack every minute (as opposed to the longer intervals I use for roll film in tanks). If you do the same, you should be okay with the same times you'd use for the same emulsion in a daylight tank with intermittent agitation. If you shuffle continuously, you'll need to *reduce* your time a bit, probably close to the 15-20% I often see quoted for Jobo and other continuous rotary processors. If you process only a single sheet, you can also do low-agitation processes like the 3-minute cycle I like for roll films, and even lower agitation; in those cases, give the same times you would for the same emulsion with the same low-agitation process in a tank (mind you, I don't think I'd want to stand in the dark for a half hour or more without even agitating the film...).

Of course, any times you get are just starting points -- some pretty subtle variations can lead to a need to adjust time for 5%, 10%, or more after you have some negatives to evaluate. Also worth noting that many/most seem to like more contrast and density in large format negatives than in 35 mm or even 120 (generally, the bigger the negative, the more contrast is seen as desirable).

thanks!

my normal process was the same as 35mm with agitation (via rocking the tray a few times) every 2-3 minutes (time distorts in the dark :p). The negs came out okay...but contrast was lower then I would have liked.

You're probably getting less agitation by rocking the tray than you're used to in 35 mm, and you might well be agitating less often than you think you are. I'd suggest trying to come up with a means of keeping time in the dark that will notify you at least once a minute (one way I've heard of working well, if you don't have a darkroom timer, is to record your own voice on a cassette or digital recorder, timed with a sweep second hand or stopwatch, and then play the recording while your film is in the developer). Try another batch and ensure you have the correct agitation interval, then if necessary extend your time or agitate a little more frequently to bring your contrast back into line.