Personal EI or film speed test procedure

[silvercloud2323]

Hi everyone,

Can anyone recommend me a good film speed test?

 

[busrider]

Most ( Zonies or non-Zonies ) "personal iso" is 1/2 box speed
The easiest test is what Vestal suggests, bracket rolls and bracket their development. You need to make contact sheets.

 

[Bill Burk]

The best film speed tests start by exposing several pieces of film in contact with a step wedge (e.g., Stouffer scale) in a sensitometer with a stable light source.

The film being tested is developed for a variety of times (e.g., 5, 7, 9, 12, 17 minutes) in a standard developer (e.g., D-76) and the resulting negatives read with a densitometer.

 

[busrider]

The best film speed tests start by exposing several pieces of film in contact with a step wedge (e.g., Stouffer scale) in a sensitometer with a stable light source.

The film being tested is developed for a variety of times (e.g., 5, 7, 9, 12, 17 minutes) in a standard developer (e.g., D-76) and the resulting negatives read with a densitometer.

... and after all that work @Bill Burk does it come out 1/2 box speed ? Zonies and their arch enemies both say the same thing
even when they aren't using D-76 a Jobo Processor and a densitometer..

 

[Andrew O'Neill]

I used to shoot a few sheets under an enlarger to a step wedge, read all the densities, and draw curves, determine dev times and EI, then test it in the field. These days, I shoot a scene that has zone I, III, VII. Do third stop brackets around half box speed. Develop. Check densities. Then do it again with different dev times for N, N-, N+. Easier and more fun.

 

[logan2z]

I followed the procedure outlined here:

Personalizing Your Film Speed, Part 1

After following the procedure rigorously for Tri-X and my condenser enlarger, the result was that my personal film speed was...

half box speed

I plan on doing it again for HP5+ and I'm guessing I'll end up with a similar result.

 

[MattKing]

Using Zone System criteria for speed you start out with a 2/3 stop reduction from ISO (box) speed.
Most people are going to end up close to that.
Any substantial difference would be due to peculiarities in what you prefer, your technique, or your equipment.
FWIW, I prefer prints made from a film exposed at a speed closer to the ISO standard - minimum exposure for preferred prints.

 

[Bill Burk]

... and after all that work @Bill Burk does it come out 1/2 box speed ? Zonies and their arch enemies both say the same thing
even when they aren't using D-76 a Jobo Processor and a densitometer..

Isn’t David Vestal the best!

It's like the time an elephant walked into a darkroom and five photographers argued about what it was. "It's a negative brush" says the photographer holding its tail. "It's a large format negative" says the photographer holding its ear. "It's a dodger" says the photographer holding its tusk. "It's a print washer" says the photographer holding its trunk. "Finally my prints are flat!" exclaims the fifth photographer holding its foot.

The difference between standards and Zone System amounts to what you say, 1/2 box speed. MattKing is right too when saying it's 2/3 stop. It's all somewhere around there.

You can expose a sensitometric strip on part of a roll of film, expose Zone System tests on the next part of the same roll, take a few regular pictures with an average meter at the full rated speed, and then finish off the roll with a few pictures exposed according to Zone System spotmetering at half the rated speed.

After developing the film to ASA/ISO contrast (about 0.62 contrast index), I would expect the sensitometric results will say the film achieved full box speed, the Zone System results will be about 2/3 stop less than rated speed. And all the pictures will come out fine. (Develop the film less, to Zone System N, about 0.58 contrast index, you'll seem to lose another third stop).

I would not be too surprised to find that the f/stop and shutter speed is the same for average readings at full speed and for Zone System readings at half box speed.

 

[gone]

I plan on doing it again for HP5+ and I'm guessing I'll end up with a similar result.

I never cared for HP5 until I shot it at 800, and it looked better than it ever did at 400, at least to my eyes (in F76 Plus). 640 might have been better, that was the first roll of HP5 I've shot in years.

 

[pentaxuser]

lieven2323, logan2z's link looks to be a very detailed and thorough test but as it is all text and not visual you may find this link to be worth a look

It is one of John Finch's Pictorial Planet videos and I found this test to be one of the easiest to follow



pentaxuser

 

[RalphLambrecht]

Hi everyone,

Can anyone recommend me a good film speed test?

the simplest is: reduce boxspeed by 1/3 top and develop according to the big development chart. the mot accurate is the the attached

 

[Doremus Scudder]

Over the years, I've re-though my film-speed testing.

First, how you determine your personal E.I. depends on how you meter. If you're a Zone System user using a spot meter to meter and place shadow values, you'll end up with a different E.I. than if you shoot 35mm using an in-camera matrix meter, etc., etc.

Also, there are different approaches to the whole "finding your personal E.I." process. Some like to nail everything down with step wedges, densitometers and plotted graphs before they make a photograph of anything important, some like to just go out and make pictures and adjust things on the fly.

I've done all the testing, exposing film in 1/3 stop intervals to a gray card then reading densities, making proper proofs, etc., etc.

I no longer think all that work is necessary. Remember, there is a rather large window of exposure and development for black-and-white negative films that will still allow you to make an excellent print. You only need to hit the window.

So, if you plan on basing your exposure on a shadow value à la Zone System and plan on making prints in the darkroom here's my advice: Rate your film at 2/3-stop slower than box speed (for starters). Make photographs, keeping careful notes about the shadow value you used to base the exposure on and what Zone you placed it on as well as where the other values in the scene fall (e.g., highlight value in Zone VIII or wherever). Don't worry about N+ or N- developments to start with. Make negatives and develop them according to manufacturers' recommendations (or a reliable recommendation for your film/developer combination if there isn't one from the manufacturer). Then, make "proper proofs" of your negatives, i.e., a proof print where the black of the clear film rebate is just a tiny, tiny bit less black than the maximum black the paper is capable of. Look at those proofs and examine the shadows, highlights and overall contrast carefully.

Then, make adjustments to your starting E.I. and development time as follows: (This may sound familiar...)
-For normal scenes, if your prints consistently have too-dark shadows, rate your film a bit slower.
-For normal scenes, if your prints are consistently to contrasty (i.e., the highlights are too bright and without detail), then reduce your development time 10%. Increase development time 10% if the highlights are too dull and dark.
-Repeat until you zero in on an E.I. and development time that allows you to print your normal scenes at a medium contrast setting (e.g. a #2.5 filter or thereabouts)
(Note, the above is for "normal" scenes, in which Zone III is a textured black and Zone VIII is a textured white).

If you want to explore N+ and N- developments (only really practical if you use sheet film), then do the same for low-contrast and high-contrast scenes (do read about where the highlight Zones need to be for each, e.g., for N-1, Zone IX is the one that should print as a textured white). With today's VC papers, this is less important.

If you plan on using an in-camera meter, then the approach is different. Rate your film at box speed (for starters), go out and make pictures. Print those pictures as well as you can and then make adjustments as follows:
-For normal scenes, if your prints consistently have too-dark, featureless shadows, rate your film a bit slower.
-For normal scenes, if your prints are consistently to contrasty (i.e., the highlights are too bright and without detail), then reduce your development time 10%. Increase development time 10% if the highlights are too dull and dark.
-Repeat until you zero in on an E.I. and development time that allows you to print your normal scenes at a medium contrast setting (e.g. a #2.5 filter or thereabouts)
-Plan on using the leeway VC paper offers to deal with scenes of different contrast.

Best,

Doremus

 

[silvercloud2323]

Over the years, I've re-though my film-speed testing.

First, how you determine your personal E.I. depends on how you meter. If you're a Zone System user using a spot meter to meter and place shadow values, you'll end up with a different E.I. than if you shoot 35mm using an in-camera matrix meter, etc., etc.

Also, there are different approaches to the whole "finding your personal E.I." process. Some like to nail everything down with step wedges, densitometers and plotted graphs before they make a photograph of anything important, some like to just go out and make pictures and adjust things on the fly.

I've done all the testing, exposing film in 1/3 stop intervals to a gray card then reading densities, making proper proofs, etc., etc.

I no longer think all that work is necessary. Remember, there is a rather large window of exposure and development for black-and-white negative films that will still allow you to make an excellent print. You only need to hit the window.

So, if you plan on basing your exposure on a shadow value à la Zone System and plan on making prints in the darkroom here's my advice: Rate your film at 2/3-stop slower than box speed (for starters). Make photographs, keeping careful notes about the shadow value you used to base the exposure on and what Zone you placed it on as well as where the other values in the scene fall (e.g., highlight value in Zone VIII or wherever). Don't worry about N+ or N- developments to start with. Make negatives and develop them according to manufacturers' recommendations (or a reliable recommendation for your film/developer combination if there isn't one from the manufacturer). Then, make "proper proofs" of your negatives, i.e., a proof print where the black of the clear film rebate is just a tiny, tiny bit less black than the maximum black the paper is capable of. Look at those proofs and examine the shadows, highlights and overall contrast carefully.

Then, make adjustments to your starting E.I. and development time as follows: (This may sound familiar...)
-For normal scenes, if your prints consistently have too-dark shadows, rate your film a bit slower.
-For normal scenes, if your prints are consistently to contrasty (i.e., the highlights are too bright and without detail), then reduce your development time 10%. Increase development time 10% if the highlights are too dull and dark.
-Repeat until you zero in on an E.I. and development time that allows you to print your normal scenes at a medium contrast setting (e.g. a #2.5 filter or thereabouts)
(Note, the above is for "normal" scenes, in which Zone III is a textured black and Zone VIII is a textured white).

If you want to explore N+ and N- developments (only really practical if you use sheet film), then do the same for low-contrast and high-contrast scenes (do read about where the highlight Zones need to be for each, e.g., for N-1, Zone IX is the one that should print as a textured white). With today's VC papers, this is less important.

If you plan on using an in-camera meter, then the approach is different. Rate your film at box speed (for starters), go out and make pictures. Print those pictures as well as you can and then make adjustments as follows:
-For normal scenes, if your prints consistently have too-dark, featureless shadows, rate your film a bit slower.
-For normal scenes, if your prints are consistently to contrasty (i.e., the highlights are too bright and without detail), then reduce your development time 10%. Increase development time 10% if the highlights are too dull and dark.
-Repeat until you zero in on an E.I. and development time that allows you to print your normal scenes at a medium contrast setting (e.g. a #2.5 filter or thereabouts)
-Plan on using the leeway VC paper offers to deal with scenes of different contrast.

Best,

Doremus

Thank you Doremus

 

[Bill Burk]

I want to point out that everyone who suggests shooting at exposures greater than the rated speed of the film, saying 1/3 stop, 2/3 stop or a whole stop greater exposure is saying the same thing. Black and white negative film looks best when you give enough exposure to reveal some detail in the shadows. “Expose for the shadows”.

The rated speed is intended to provide the least exposure that will give enough detail for an excellent print.

All the tests which conclude that a film is half its rated speed actually confirm the film meets its specifications and is at its rated speed.

Then the photographer gives a little more exposure than necessary and enjoys the results. It’s a positive feedback loop.

 

[Doremus Scudder]

Bill,

It seems that using Zone System shadow-placement metering techniques really likes a lower speed rating. I really think it has more to do with the visualization/metering/placement loop than the actual film speed (which is tested out pretty reliably by the manufacturer to determine ISO).

On the other hand, working with a modern SLR and an in-camera high-falootin' matrix meter, box speed seems a better starting point to me.

Thoughts?

Doremus

 

[MattKing]

Doremus,
The actual, scientific criteria for ISO speed for films - which is based on contrast and density rather than just density over base fog- is by the nature of how the two are defined, 2/3 of a stop higher than film speed determined using Zone system criteria.

 

[Sirius Glass]

Doremus,
The actual, scientific criteria for ISO speed for films - which is based on contrast and density rather than just density over base fog- is by the nature of how the two are defined, 2/3 of a stop higher than film speed determined using Zone system criteria.

That is why I use box speed for most of my photographs and when I want more shadow detail I use the Zone System at Zone 2, Zone 3 or Zone 4 as the subject matter dictates. I do not arbitrarily limit myself by derating the film.

 

[Bill Burk]

Doremus,

MattKing said what I was going to say.

The two systems were setup differently, amounting to about 2/3 stop difference.

When you meter by Zone System, the Zone System speed is the right one to dial into the meter. Because you are evaluating as if to place shadow key black at Zone I = 0.1 above base plus fog, four stops below the metered Zone V.

When you shoot with a Nikon F6 (to name a camera known for its accurate metering), then the box speed is right. It aims to put key black at 0.1 above base plus fog too, but it’s targeting 3 1/3 stops below the meter reading.

The general rule could be: when usung Zone System, use 2/3 stop less than rated speed. When doing regular metering use the rated speed. If you go back and forth, it doesn’t hurt to always set 2/3 stop less than rated speed, in case you forget you won’t underexpose a shot. Many photographers like the extra shadow detail.

 

[Sirius Glass]

Doremus,

MattKing said what I was going to say.

The two systems were setup differently, amounting to about 2/3 stop difference.

When you meter by Zone System, the Zone System speed is the right one to dial into the meter. Because you are evaluating as if to place shadow key black at Zone I = 0.1 above base plus fog, four stops below the metered Zone V.

When you shoot with a Nikon F6 (to name a camera known for its accurate metering), then the box speed is right. It aims to put key black at 0.1 above base plus fog too, but it’s targeting 3 1/3 stops below the meter reading.

The general rule could be: when usung Zone System, use 2/3 stop less than rated speed. When doing regular metering use the rated speed. If you go back and forth, it doesn’t hurt to always set 2/3 stop less than rated speed, in case you forget you won’t underexpose a shot. Many photographers like the extra shadow detail.

Based on your post if one uses Nikon AF slrs then one should shoot box speed. Time to sell off the Canons and Leicas.

 

[Paul Howell]

When shooting 35mm based on my testing my newer bodies with matrix metering seem to shoot at box speed. With older bodies non electronic shutters and CCD meters it is all over the map, some spot on others up to 2 stops off.

As I don't have a densitometer I test by setting a scene, in open shade my wife for zone VI, holding a gray card, zone V, with a swatch of black cloth with texture zone III and a white cloth with texture zone VIII start with ASA/ISO 25, shoot a frame, use a lens cap to shoot a blank, then shoot a frame at 50, another blank so on until 1600 develop at manufacture's recommendation and make a contact print grade 2, then find the frame with the tested ASA/ISO that comes closest to Zone III to VII.

 

[Craig]

I plan on doing it again for HP5+ and I'm guessing I'll end up with a similar result.

I did the testing procedure described by Bill in post #3 and I ended up with HP5's speed being 500.

 

[Sirius Glass]

I did the testing procedure described by Bill in post #3 and I ended up with HP5's speed being 500.

And you will end up with thin negatives lacking details especially in the shadows. So much for endless useless wasteful unnecessary testing. One can never test a film as much as the manufacturer has already done.

 

[pentaxuser]

I did the testing procedure described by Bill in post #3 and I ended up with HP5's speed being 500.

I wonder how we reconcile this?

pentaxuser

I followed the procedure outlined here:

Personalizing Your Film Speed, Part 1

After following the procedure rigorously for Tri-X and my condenser enlarger, the result was that my personal film speed was...

half box speed

I plan on doing it again for HP5+ and I'm guessing I'll end up with a similar result.

Quite likely.No coincidence that an understatement for instance is known as a British understatement. Like most things British it is always best to underrate it. Things tend to be slower here. We're a half box speed nation

pentaxuser

 

[Craig]

I wonder how we reconcile this?

I was using replentished Xtol for my testing and when I achieved a contrast that works well for my enlarger, the speed came to 500. It will be different for other peoples developer choice, style of agitation and target contrast.

 

[Sirius Glass]

I was using replentished Xtol for my testing and when I achieved a contrast that works well for my enlarger, the speed came to 500. It will be different for other peoples developer choice, style of agitation and target contrast.

Is that the speed bump that replenished XTOL is supposed to provide?