degruyl
Just this guy, you know?
Stupid question: How do you check if your chemical thermometer is reading correctly?
I mean, does anyone check?
I mean, does anyone check?
KenR
Well-known
It really shouldn't matter if it is calibrated against a standard as long as you use the same thermometer each time when you process your film or prints. There are so many variables involved in processing (pH of water, aggitation as well as meter differences between cameras etc.) that you have to find what works for you. The times in the manufacturers literature as well as web sites like the Massive Developing Chart are only guides. As they say "your milage will vary" and so if your temperature is a degree or so off it really won't matter as long as you standardize everything for you.
MartinP
Veteran
For developing film use an alcohol thermometer but get a certified one (to take care of any accuracy question) and one with a scale matched to the process temperature you will be using (to improve the precision). So long as it is consistent from one session to the next there should be no problem with a degree or so of accuracy anyway.
On the other hand, the metal dial-thermometers are neither accurate nor consistent - but can be useful in developing trays as you can check the 'real' temperature, with the alcohol-thermometer, then note any change from whatever is indicated on the dial-thermometer in order to get an idea of whether the chemicals are cooling down or warming up. This is an advantage because the dial-thermometers are relatively cheap, and also relatively robust for knocking about in paper trays.
On the other hand, the metal dial-thermometers are neither accurate nor consistent - but can be useful in developing trays as you can check the 'real' temperature, with the alcohol-thermometer, then note any change from whatever is indicated on the dial-thermometer in order to get an idea of whether the chemicals are cooling down or warming up. This is an advantage because the dial-thermometers are relatively cheap, and also relatively robust for knocking about in paper trays.
degruyl
Just this guy, you know?
I think I was having trouble simply because I have a dial thermometer. For tank developing, I certainly don't need something I can read in the dark...
To elaborate, I was noticing inconsistent results.
Thanks
To elaborate, I was noticing inconsistent results.
Thanks
giellaleafapmu
Well-known
You need to calibrate your developing times with the way you take temperature and the concentration type of water you use, it does not matter whether you can measure precisely the temperature or not. The classical book of Ansel Adams "The negative" is probably the authoritative source on how to do this.
GLF
GLF
Ronald M
Veteran
Ice water is 32 Boils at 212 F.
Get one good "master" and a few working ones. Calibrate the working one against the master from time to time.
I have two Kodak process thermometers. One was new 30 years ago and was treated with care. The othe was a gift a year ago and well used. They differ by 1/2 deg F @ 68. They are supposed to be accurate to 1/4 deg. I may have two at the end of the tolerence range. This is like the man with two watches. He does not know what time it is. Before the atomic clocks that is.
The two working dial ones are checked at 68 for monochrome and 100 for color and they correction is written on the wall. It has not changed in decades.
Get one good "master" and a few working ones. Calibrate the working one against the master from time to time.
I have two Kodak process thermometers. One was new 30 years ago and was treated with care. The othe was a gift a year ago and well used. They differ by 1/2 deg F @ 68. They are supposed to be accurate to 1/4 deg. I may have two at the end of the tolerence range. This is like the man with two watches. He does not know what time it is. Before the atomic clocks that is.
The two working dial ones are checked at 68 for monochrome and 100 for color and they correction is written on the wall. It has not changed in decades.