The Best Photography Darkroom Equipment: Film Development Thermometer


The Best Photography Darkroom Equipment: Film Processing Thermometer

A mini review of the Weston Dial Darkroom Thermometer

If you are serious about developing your color or black and white film images,
you must get,
and use faithfully,
your own film developing thermometer.
That’s it.

No doubt.

This post is about my favorite film developing thermometer,
and, why it’s the best.

The only way to get control of your process
…your pictures…
to get the kind of look you’ve seen in other photographers’ images…
or want to have in your own…
is to control your darkroom techniques and film development.

I mention this to my beginning photography students.
My 2nd semester students get pushed towards getting their own film development thermometers.
By the 3rd semester, when I introduce the Zone System, students are required to get one, finally.

Most darkroom photography workers can relate this to their black and white pictures,
but it’s also relevant to color photography.

There are several options available in film processing thermometers
ranging from cheap mercury-in-tube ones, dial types, or digital models,
all the way up to pricey versions in analog and digital styles.

A film darkroom thermometer that suits me has to have the following attributes:

  • Accuracy (obviously!)
  • Repeatability (meaning that it reads the same temperature the same way each time)
  • Speed in reaching its correct reading
  • Ease of use (utility and readability)
  • Reasonable pricing

This Weston thermometer model I’m recommending has the best balance of accuracy, utility, readability and price.

Smaller thermometers are harder to read.
For a few dollars more, you can get the Weston 3” dial Stainless Steel model with Dual scale and their very helpful Mirroband feature.

The specifications claim an accuracy of +0.25% at 68°F
and within + 1° over the remainder of the range.
These kinds of ratings are essential for consistent film development.
Many thermometer makers kind of hide the specifics and don’t state numbers in the range that is critical to black & white film darkroom workers.

Now, with any type of analog thermometer, mercury or dial type,
the angle you view it at can change the temperature it seems to indicate.
Here is where the Weston Mirroband feature comes to the rescue in a completely easy-to-use way.

In this close up, you can see that the reflection of the indicator needle is out of alignment with the needle itself, meaning the temperature reading is slightly off. It looks like the temperature is 73º


In this shot, the needle, and it’s reflection, are lined up precisely leading to a correct reading.


This detail shot confirms the alignment. It shows the correct temperature of 72.5º


In use, it’s totally easy to view the correct reading. This is the area where a larger 2.5” or 3” dial is so much easier to read repeatably than a smaller 1” one.

The competing model ‘Legacy 2.5” Pro’ has a luminous dial. While that might be helpful in some darkroom situations, having something glowing in the dark goes against my ethics to make a darkroom, well… dark. (BTW, remember to put away your luminous dial watch, and MP3 player, cell phone, etc., before loading film into the developing can!!!)

Another note, if you’ll be traveling to a lab (such as at a school) keep the box the thermometer comes in.  The stem must remain straight. Any bend will void the accuracy of this type of thermometer.


The box will help you keep on the straight and narrow, temperature-wise anyway :> )

Proper care of this essential piece of equipment will ensure many, many rolls of consistently developed film.
I’ll be posting further articles in the series to help you improve your film and other darkroom techniques.

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PhotographyUncapped Item Seal of Approval

Hope you found this little thermometer mini review helpful,

and, as in a black and white dark room, or in life, KEEP DEVELOPING!

Ken Storch

Author: P U

9 thoughts on “The Best Photography Darkroom Equipment: Film Development Thermometer

  1. This is really helpful.
    I just started a class, and the school’s thermometers suk.

    I’ll think about getting one of these.

  2. Wild,

    Schools usually can’t afford better thermometers since they get broken, often,
    sometimes they ‘walk’.

    Also, only beginning students would use someone else’s thermometer.

    The fact that you are thinking about it, means you are ready for move up
    and get your own!

    Good luck.

  3. hi ken,

    could you please contact me via email? I am an Arthemia Premium user and would like to ask you one thing regarding the sidebar set up.

    thank you,


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