Film speed testing without a densitometer

[David Home]

Thanks for all the comments.
I will keep my eyes open for a transmission only densitometer.
In the meantime I will use my light meter and look for a 1/3 stop drop with the correct negative.
Regards, David

[Bjorn Nilsson]

You don't need a densitometer.

Here's a brief article that shows you one method. In a nutshell, you try 3 different film speeds, and 3 different developing times.

I'm very much with Ken on this subject. While I own a densitometer, the testing is at best quite tedious. It's also very easy to get caught in an endless testing stage, so that all you do is testing with all the various excuses like, "I'm still not really done with testing that particular combination ...".
So see to that you are getting your negatives close to perfect (where Ken's method is a very good approach) which is much better than most of the classic master pictures had anyhow.

//Björn

[philbed]

There is an excellent article here :
http://www.paulwainwrightphotography..._your_eyes.pdf
You can test your film without a densitometer. Although I own a densitometer, I prefer using Paul's method. As he states on his article : we exhibit prints, not negatives. IMHO it is the simple way to achieve quickly a first good print.

[RichardRitter]

In the DVD book "Finely Focused" there is an article on the Zone I test using a ND filter 0.10, clear film and your enlarger. I have ran the test and checked it against a densitometer and it works.

The DVD info is here http://circleofthesunproductions.com/FinelyFocused.htm

[Louie Powell]

Here's a way to do the film speed test that doesn't require a densitometer.

Film speed is assessed in shadows. Zone I negative density is defined as the density of the film base plus processing fog, plus 0.1.

Run a series of text exposures of a blank, white target. For these exposures, pretend that the target is Zone I - that is, meter the white target, and then give it four stops less exposure so that it records on the film as Zone I. Process normally.

Now, get a small piece of 0.1 neutral density filter. Place the film on a light box, and lay the filter chip on top of the film such that it covers the rebate (unexposed edge of the film), but not the exposed area. Choose the exposure in which the brightness of the exposed area most closely matches the brightness of the rebate plus filter. That exposure represents the proper film speed for your particular combination of film, processing and metering.

If you want to get scientific, you can use a spot meter to compare the brightness of the exposed areas with the brightness of the rebate plus filter chip. My view is that the objective is to find a film speed that results in good shadow detail, and life is too short to make it rocket science.

Incidentally, I've tested many bulk rolls of T-Max 400, and in every case, this test came back with the conclusion that the 'ideal' speed for that film in my Nikon FM-2 and with my processing was in the range of 160-200.

To determine the proper development time, you have to to the test on a Zone VIII exposure. After finding the proper film speed, expose a group of negatives at that speed, and then process them individually, varying the development time in 30 second increments. Set up your enlarger to make a print, and determine the printing exposure required to make the rebate just barely darker than the maximum black that you can achieve on your standard printing paper. Then, holding that exposure time, make a series of test prints of the Zone III negatives. Process them all at once (to assure that they each get exactly the same development). Choose the print where the test exposure is about one Zone darker than blank white paper. The negative from which that print was made was processed at the ideal processing time.

[Andre Noble]

I did one of these tedious film speed tests, but I got caught up in the details, I lost sight of the big picture - and since my articular test still had a subjective component, my film speeds were still inaccurate.

So for now, based on recommendations from people. I consider experts, I am just going to rate all B&W films at 1/2 their box speed. I'm referring to traditional films such as FP4, HP5, Plus X, Pan F, and Tri-X.

[Chuck P.]

While I own a densitometer, the testing is at best quite tedious. It's also very easy to get caught in an endless testing stage.....

I've done testing with and without a densitometer and it's far more tedious without a densitometer than with one, IMO. Being able to determine the optimum film speed along with the characteristic curve with one sheet of film, a step wedge, and a densitometer is a piece of cake. Because of it's simplicity, I would be much more willing to explore various film/developer combinations........in short time to boot.

[seabird]

There is an excellent article here :
http://www.paulwainwrightphotography..._your_eyes.pdf
You can test your film without a densitometer. Although I own a densitometer, I prefer using Paul's method. As he states on his article : we exhibit prints, not negatives. IMHO it is the simple way to achieve quickly a first good print.

Thanks for posting this. I agree that it is an excellent article. It appears so simple that I'm even tempted to try it!

Regards