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Film developing slide ruler

smithdoor

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Nov 2, 2013
Messages
134
Location
Clovis CA
Format
4x5 Format
Film developing slide ruler

Here is one way of getting the developing time works great
A simple slide ruler for developing

All you need is the time and temperature an 68F/20C of the film and developer slide the ruler to that location. Then just take the temperature of your developer and find on the slide ruler and there is the time you need for your film.

Dave
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Interesting. Would this work with any developer....I'm wondering whether the activity of all developing agents varies in the same way with temperature ?
 
An interesting gadget and in a way more analogue than a table I note that it indicates that a higher temp = higher contrast. Is this the case. I always assumed that more agitation or longer dev time at a constant temp gave higher contrast but temp by itself didn't

pentaxuser
 
Hey Dave,
Where'd you get this slide rule?
 
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This is excellent, was considering attempting something similar, but my efforts would not have held a candle to this.

Your file has been printed, cut and glued to bits of card - my new slide rule may just replace the tedious tables, graphs, electronic calculator and could take some load off the Massive Dev app. Have marked off the +15% points for the two partial exhaustion tiers of Xtol (can't resist 'hacking' it).

I am impressed.
 
Letting it slide

Slide ruler? I haven't heard about one of those things since Buicks had fender portholes. Nerds used to carry them around like badges of honor. What is next, the armillary sphere? Whutever works, huh?
 
When I was in high school, your grades in math classes were directly related to how good a slide rule you could afford. The expensive ones
had much finer and easier to read markings. Looking up logarithms and trig functions in a handbook was just too slow for the given test session. Nowadays you can just buy a ten buck calculator that does all that correctly, and never yourself understand the math behind it. I had
a roomate in college who could do log calculations of seven-digit numbers in his head faster than you could punch computer buttons. But he
couldn't spell words like "that" or "was". He literally became a rocket scientist.
 
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