View Full Version : Temperature Compensating timer for the SP-445

7-Feb-2017, 16:30
We're looking into building a temperature compensated timer specifically for our SP-445. Basically, it would monitor the temperature and adjust the time according to the standard processing tables.

We'd like your feedback; you can take the poll via the newsletter: http://conta.cc/2koMQOr (http://conta.cc/2koMQOrhttp://)

And yes, it could easily be adapted to other tanks/trays.

Keith Pitman
7-Feb-2017, 16:40
Are you familiar with this: http://www.curtpalm.com/Software.html?

8-Feb-2017, 14:40
Yes, we've seen it and several others. We will offer a solution tailored to our SP-445.

9-Feb-2017, 03:44
The conta link doesn't seem to work.
But do you think it's really essential to have this kind of functionality? For b&w work, I've never seen deviations during development that caused me any worry. I'm sure some people will fuss over this, but I'm quite skeptical. Then again, it may make sense for people in very hot climates...

Mike Bates
9-Feb-2017, 11:12
I had considered building something like this for myself.

My plan was to use something like the Vernier Go Direct (http://www.vernier.com/products/sensors/temperature-sensors/gdx-tmp/) temperature probe (when it becomes available, Spring 2017) mounted through the vent hole cap.


The probe is waterproof and Bluetooth wireless. I'd have to write a small app for my phone, tablet, or computer (TBD).

The benefit to me is accurate, no-fuss room temperature B/W development. I wouldn't bother for any step beyond the developer.

If you can produce something similar at a reasonable cost, it would save me the trouble.

9-Feb-2017, 21:42
Don't think you'll get it through on vent side; you could glue it the Fill/Drain cap. Here's another idea we're kicking around:

Mike Bates
9-Feb-2017, 22:16
Yes, of course. I wasn't looking at my tank when I wrote that. The temperature probe must go through the fill cap and be sealed well enough for inversion agitation.

Peter Lewin
10-Feb-2017, 06:06
Two observations: those who have the ZoneVI timers (or similar?) love them, those who have never used one don't see the need. Second, the ZoneVI timer is at least as useful for printing (maybe more so than development) because the sessions are much longer, with greater likelihood of temperature shift. In my unfinished basement and darkroom, summer is fine, but in winter the ambient temperature is around 62 and the developer in my print tray definitely changes a lot.

10-Feb-2017, 09:28
Peter, for printing it would make much more sense to me than for film development, precisely because of the temperature shift during longer sessions that you pointed out. For film development, I just start out with the developer at the right temperature and I find it doesn't shift enough during development to worry about. Any gain in accuracy would be irrelevant in the light of all the other process parameters that I don't control that strictly - or cannot be controlled very accurately in a practical manner (think of usually non-calibrated apertures and shutters in LF lenses).