tube agitation

[robert fallis]

I've got some Shanghai 100 iso pan film, the recomended development time is 10 min in d76, but I'm using home made tubes to develop it, this means that the agitation is constant, does this effect the development time? I'm getting very dark negatives, I've googled a lot but imformation is rare. does anyone have any ideas.

bob

[Stan. L-B]

Hello Robert.
Yes it does. If you have the deveoper dilution and temperature correct, then I would suspect that your agitation is far too vigourous, be gentle and consistant. Ten Mins. for developing time is reasonable. Stan. L-B

[Brian Ellis]

If you don't plan to do the testing you should do then as I recall the rule of thumb when basing constant agitation times off of periodic agitation times is to reduce the periodic time by about 20%.

[Bruce Watson]

I've got some Shanghai 100 iso pan film, the recomended development time is 10 min in d76, but I'm using home made tubes to develop it, this means that the agitation is constant, does this effect the development time?

Agitation certainly effects development time. As you would expect, how much is dependent on the film, developer, how much agitation (constant, but how fast, and how even), temperature, your exposure, etc.

What it comes down to is calibrating your process. There are two basic things to find out. One is your personal exposure index (EI). The other is your personal normal development time.

Consider reading up on these topics. A couple of excellent books are Adams' The Negative and Picker's Zone VI Workshop. Both cover much of the same material, but they cover it in completely different ways. One may make more sense to you than the other. There are dozens of other books out there on the subject as well.

[PMahoney]

I would second the notion for testing for your specific EI. I, myself, develop in homemade tubes and had originally developed FP4+ by dropping 'normal' development times by about 15% in ID-11 (D76). It worked well enough, but ultimately I wasn't entirely satisfied. I eventually tested my process (film) using a similar protocol as that found in Ansel's The Negative, but modified it slightly to test the density on a flatbed scanner. Relatively simple to do and worth the effort.
Peter

[robert fallis]

I've order Ansel Adams book from Amazon, so I will do some testing, the Shanghai film is cheap enough, and all being well it should be a quiet sunny summer, so hope to produce a decent negative, by September!!!!!!

bob