The magic of the number 3.14 & the magic of film development.

[KitosLAB]

In my youth, this method of determining film development time was very common. Perhaps he is known even now, but I don’t find information about this, so I think that it can come in handy in many cases. The essence of the method: We cut off a small piece from the edge of the film, which is half immersed in the developer, at the same time turning on the stopwatch. Wet emulsion first brightens, then under the influence of the developer begins to darken. We catch the moment when the color of the dry emulsion and the wet emulsion become the same. At this point, we turn off the stopwatch. We multiply the resulting number of seconds by 0.314 and get the development time in minutes. In my case there was Fomapan200 film of unknown hand winding, unknown diluted methol/hydroquinone developer and not exactly known temperature. When the color of the emulsions leveled off, the stopwatch showed 62 seconds. 62 х 0.314 = 19.468=19.5 Yes, if the development time was 6 - 9 minutes, one would assume that I "guessed" and I was lucky. But guessing 19.5 minutes is impossible. This confirms that the method works quite effectively and can be useful in cases where there is uncertainty during development. One of the photographs of the developed film. You can see more photos from this film in the monthly topic and in the Street shooting topic. Premier PC488 camera

 

[John Wiegerink]

Yes, I've done this a couple of times, and it seemed to work pretty well. Back when I tried it, it was called a Russian film test. Now you just come to one of the forums like this and just ask, "What times do you have for X-film in Y-developer"? You then glean that information, and you'll get a good starting point. I do like your method better since it's more hands-on. Of course, most film manufactures have their own suggestions.

 

[snusmumriken]

Are you using the light-exposed film leader, or the unexposed tail, or a piece with a representative image? Or doesn’t it matter?

 

[relistan]

Probably there is some range of films and developers for which this works. I had heard about it from a video John Finch did, where he had no luck at it at all:

 

[faberryman]

Sounds pretty helpful for those times when you don't know what film you are shooting or what developer you are using. I am sort of curious how Pi figures into the equation, particularly as a mechanism for converting seconds into minutes.

 

[KitosLAB]

Are you using the light-exposed film leader, or the unexposed tail, or a piece with a representative image? Or doesn’t it matter?

I don't think it matters. I did this many times, it happened from the beginning, it happened from the end. In this particular case, it was the end of the film

 

[KitosLAB]

Probably there is some range of films and developers for which this works. I had heard about it from a video John Finch did, where he had no luck at it at all:

I don't know English at all. I write and read using a translator, but I can't hear. It is very interesting to me. You cannot briefly explain his method. As far as I understand it is different from mine. Everything is simple for me
62sec x 0.314 = 19.5 min
But if the stopwatch showed 16 seconds then:
16 х 0.314 = 5 min
I have a very expired ORWO Chrome film. I save it for spring / summer, for the color season. When I develop it, I plan to determine the time of black / white manifestation in this way

 

[MattKing]

Do you think that it is important that 0.314 is 1/10 of the approximate value of π?

 

[KitosLAB]

In fact, 30 - 40 years ago, mi was multiplied precisely by 3.14 and subsequently simply moved the comma)) they got 195, but counted 19.5 minutes. I think that this 1/10 does not matter for two reasons 1 - the number still remains beautiful, 2 - the method really works

 

[Donald Qualls]

I'd be interested to see this experimentally confirmed the other direction -- that is, for film/developer combinations with a known "normal" development time, see what this test gives. I suspect it'll be "close enough to get an image" in most cases, but likely not precisely correct. Perhaps I'll give it a try next time I have a beaker of D-23 and a clip of the same film I'm processing.

 

[John Wiegerink]

I'd be interested to see this experimentally confirmed the other direction -- that is, for film/developer combinations with a known "normal" development time, see what this test gives. I suspect it'll be "close enough to get an image" in most cases, but likely not precisely correct. Perhaps I'll give it a try next time I have a beaker of D-23 and a clip of the same film I'm processing.

Donald,
Try it, you might be surprised. I think I did it with Ilford ID-11, but not sure which film I used. It might have been the old Shanghai GP3 stuff.

 

[Donald Qualls]

It might have been the old Shanghai GP3 stuff.

I'd be more inclined to use a more mainstream film, like Fomapan 400 or Tri-X, with well known characteristics -- GP3 hasn't got that much history in the US.

 

[logan2z]

The first time I heard about this was in this video (the person in this video uses 3 rather than 3.14):



I was skeptical and never tried it but perhaps there is something to it.

 

[logan2z]

Do you think that it is important that 0.314 is 1/10 of the approximate value of π?

Maybe it only works for π-ro developers

 

[KitosLAB]

The first time I heard about this was in this video (the person in this video uses 3 rather than 3.14):



I was skeptical and never tried it but perhaps there is something to it.

Yes, in fact, it started as 3. And when I was 15 years old, they told me about 3. But during our service in the army, we showed a lot of films in secret from the officers. And that's when this adjustment came 3.14

 

[Paul Howell]

Thanks for tip, I had forgotten about this method, we discussed it in college, I think another student did a paper and testing using it, don't recall if he used 3.14 or another value. I might give it a whirl.

 

[pentaxuser]

The second presenter give credits to Viktor Petryakov Anyone know who he is/was and what his pedigree is in film chemistry, developing and range of films and developer on which it worked ?

His test on each occasion seemed to leave a lighter square in the middle that didn't match the original emulsion but the outer square was darker than the emulsion. However this may have occurred after he had finished the experiment in each case

It appeared to work for Rodinal and while he mentioned it worked for other films he doesn't say which nor was it clear to me which other developers and films he had tried this method with

He seemed to suggest we try with horse urine or coffee based developers as well so he appears to be sure about those as well

I was left with doubts about its universal applicability for all films and all developers and John Finch's conclusions added to my scepticism as well

My jury is very much still out on this. It might just be that as long as you use Rodinal it will work with all films but there is no evidence presented

pentaxuser

 

[pentaxuser]

Kitolabs which films and developers that you have tried have worked with this 3.14?

Thanks

pentaxuser

 

[aparat]

Kitolabs which films and developers that you have tried have worked with this 3.14?

Thanks

pentaxuser

I was just going to ask that

It's a great tip. There have been times in the past when I was agonizing over choosing a developing time for an unknown (to me) film and developer combination.

I was also curious if anyone knows any other easy universal developing tricks, such as a common technique for most films and developers, etc.

 

[warden]

I don't know English at all. I write and read using a translator, but I can't hear.

I wouldn't have known you were using a translator. It's amazing how good they are! I'm glad the translator is working so well for you because now we get to see your images from Ukraine.

 

[faberryman]

I am a little puzzled about the concept of an unknown developer. Does this happen when you go into an unfamiliar darkroom, see a bottle labeled "Developer" on the shelf, and decide you'll give it a try even though you don't know what it is? Why would you trust your negatives to an unknown developer? I must be missing something obvious. It wouldn't be the first time.

 

[John Wiegerink]

I'd be more inclined to use a more mainstream film, like Fomapan 400 or Tri-X, with well known characteristics -- GP3 hasn't got that much history in the US.

Yes, but that's why I tried this method on GP3. I didn't have much information on developer combos for GP3 at the time.

 

[Oldwino]

Hey, somebody should try this with that new CatLabs 320!

 

[Richard Man]

You are just multiplying the measured time by 18x ( / 3 ), or 18.84 ( / 3.14 ). I bet a film chemist would know the magic relation between the base fog and the "developed" time and light sensitivity

 

[Craig]

Do you think that it is important that 0.314 is 1/10 of the approximate value of π?

I can't see how there would be a correlation other than coincidence.