Drop test developing time...

[rai]

Hello everyone!!!
Know someone the drop method to calculate the development time of a film with a particular developer?
We need:
*A stopwatch or something that allows us to have seconds.
*The developer
*A piece of fogged film.
Procedure:
You take a piece of fogged film, (the same that we will develop) and put a drop on emulsion face and starts the timer. Change color first, it will become clearer, then take the same tone as the emulsion and become darker than the emulsion, at this moment stop the timer. The total number of seconds we divide by 4 and already have the development time of photographic film in minutes. We'll have to experiment, but the approximate time is pretty accurate. Never fails if the movie and the developer are well.
This method as we used when we did not have timesheets, the books were difficult to obtain and internet did not exist.
Comments?
Sorry for my bad english.

 

[Jim Noel]

AN interesting idea. I'll have to try it soon.

 

[wblynch]

...The total number of seconds we divide by 4 and already have the development time of photographic film in minutes.

So, if it takes 60 seconds, then divide by 4 = 15, meaning development time is 15 minutes?

Sounds easy. I will try it because I have some 25 year old film that I can not find any development times for and my first guess was wrong.

Thank you.

-Bill L.

 

[nworth]

It sounds very approximate. It would be hard to get consistent in judging what is "darker than the emulsion," especially since emulsion colors differ. This method tries to judge when development just begins, the extrapolates it to what is the time for full development. I'm not sure that the induction time has the same relationship to full development for all film and developer combinations, either. Even if the method could get you in the ballpark, you would need more work to determine the right development time for the proper contrast with a particular film.

 

[rai]

So, if it takes 60 seconds, then divide by 4 = 15, meaning development time is 15 minutes?

Sounds easy. I will try it because I have some 25 year old film that I can not find any development times for and my first guess was wrong.

Thank you.

-Bill L.

Yes... 60/4=15 OK.

 

[pentaxuser]

It seems to me that you could test the reliability by taking a known film, known developer, do the test and from the formula decide on the development time then check it against the manufacturer's recommended development time.

If you did this with a few different films and developers and it was reasonably accurate each time then it sounds as if you have a reasonable test.

pentaxuser

 

[rai]

I have used this method many times and work well. The environmental conditions, conservation and manufacturing of developers are different in each case and in every home, exceptions that some may have. If we put a 60 (or more) watt bulb at 40 cm approx. will see the color change quite well. This week I made three batches of Parodinal with slight modifications between them. The development chart times for Parodinal indicate the same as for Rodinal,other people use diferents rates. With this test I got different times (15-17 and 21 minutes) for Fuji film 100 SS and very similar results with my three Parodinals, I'm happy with Parodinal and the drop test. I invite you to try this method.

 

[Athiril]

I've always simply mixed up my working solution/dilution, put a few drops on, and time it how long it takes to reach black, usually tilt the film every minute to move some developer to a fresh part of the film so I can see when it stops getting darker.

I've used the time I've simply measured directly, with good results.

 

[rai]

I've always simply mixed up my working solution/dilution, put a few drops on, and time it how long it takes to reach black, usually tilt the film every minute to move some developer to a fresh part of the film so I can see when it stops getting darker.

I've used the time I've simply measured directly, with good results.

Hi Athiril!, the resulting time in seconds or minutes?

 

[wblynch]

I tried this, both ways, and I got very overdeveloped negatives. I think I'll go back to the charts.

 

[Bill Burk]

Since I was processing film this weekend I did the drop test:

I use TMY-2 and develop in 13 1/2 minutes to a good approximation of ASA standard time in D-76 1:1 at 68F

I dropped some 1:1 D-76 on the emulsion of a spare sheet and watched it lighten then darken to match background in approximately 20 seconds. Then I took D-76 stock solution undiluted and did the same and it lightened-then-matched in approximately 10 seconds.

I viewed the film in open shade at a slight angle so the slightly magenta emulsion shimmered. At different angles I saw different emulsion color and lightness, so the results could vary widely.


For 5 minutes in D-76 1:1, I would get a contrast index of 0.3


Seems it might be useful check for developer activity before developing some important shots, but I wouldn't want to base development time on it.