Underrating manufacturers ISO speeds for B&W Film

[kenneth]

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I read various articles by the likes of Ansel Adams and Barry Thornton about underrating B&W film and not working to manufacturers ratings. Some say by 30%, others by as much as 50%.

 

I can only assume the reason for this is the tendency on camera light meters to give 18% grey scale readings which in alot of cases is too high when an overall reading is taken. However, if you point the camera or light meter at the area with the shadow detail you wish to expose as visualised there shouldn't be a need to down rate ISO settings should there?

 

I would be interested in hearing others comments on this concerning different film stock.

 

I personally have now standardised on Ilford Pan-F 50asa and Kodak Tri-X 400asa setting the manufacturers ISO ratings on my M6 bodies and opted for selective area meter shadow detail metering with the M6's built in meter. Leica refer to the meter in an M6 as a fat spot meter which I assume means that it is trying to be all things for all men.

 

I guess the other consideration might be a spot meter to meter shadow areas more accurately.

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[Walt Calahan]

Actually it has more to do with the type of developer that is used then the lightmeter.

 

Some developers will not give the manufactures speed.

 

That said, a 1/3 stop adjustment down might simply be how the photographer prefers how the negative is rendered.

[andybarton]

Ansel Adams' advice is only really relevant today if you are processing your individual frames individually.

 

On the assumption that you process a whole roll at a time, the advice may be different.

 

I use Tri-X almost exclusively unless it's Pan F+ weather. I rate them at 320 ASA and 32 ASA respectively, and I cut the developing time by around 15%. This, in my experience, retains the shadow detail and stops the highlights blowing out in the vast majority of cases.

 

Now, Tri-X is a very forgiving film. I rated the front of a film at 1600 ASA in a dark room in the Schindler factory in Krakow last Autumn, and the remainder of the film at 320 when I got outside. The whole roll was processed as normal and I got useable negatives from the front and the back end.

 

1600

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320

[StS]

This image was taken on BW400CN. If I remember correctly, I underexposed it by mistake by five stops.

 

Sure this is technically a poor photography, just to show how extremely tolerant black and white film can be...

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[budrichard]

By using an ASA different than the one quoted by the manufacturer your a tailering the ability of the emulsion to record a certain range of tonal values to the tonal range of a scene. Not all scenes have the same range of tones. A snow scene in bright sunlight has a very wide range of tones and what one usually does is to underexpose this type of scene or tonal range and then tailer the development of the film to capture as best the tonal range of the scene. Scenes with low contrast, typical of s scene at night are usually underexposed and the development time increased to bring out the toanl range on the film. Learning the various Zone systems will help you understand the mechanics but you must also be able to control your own devlopement times. I read where someone said you could use a simplified zone system without development modifcation but I never used it that way because I always shot my film for a specific situation.

Good luck it will take time and effort but your prints will be superior.-Dick

[micky]

;)I´ve found out that if you want to have as near perfect results as possible you have to experiment quite a lot.

Everyone has his/hers own methods of developing, own chemicalpreferences and even if we would use the same type of camera, the lightmeters would still differ slightly. The iso on the box could be a 1/3 or 2/3 less or more on your particular camera.

Therefore one has to find his own combination of iso and developer and time.

The iso on the box is just a startingpoint. And once you´ve found your combination of developer and iso and time, stick to it.

A combination that works for you is the best startingpoint for adjustments according to the Zonesystem.

One has also to find a combination that works for the whole roll if one is shooting 135.

An idea could be to shoot low iso and short dev-time in bright sun and increase both with increasing clouds. Then you ´d get acceptable negs that would work in situations that don´t differ too much in contrast.

A second idea is also to buy bulkfilm and cut lenghts that are just enough for the day or situation etc. If you shoot 135.

[tgray]

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While all of the above is true, I just wanted to say that it also depends on your metering technique. And also how your meter is calibrated - most are NOT calibrated to read 18%, but something around 12%. This probably accounts for a lot of the common advice to downrate Tri-X to 320 or 250, because by blindly assuming your meter reading is based on 18% when it's actually 12%, you are underexposing a half a stop from where you thought you were.

 

I rate at box speed and never seem to have a problem with my negatives. But I use XTOL, a speed enhancing developer, and am pretty cautious with my metering. If you do the oft-quoted "meter on the shadows and stop down two stops" technique, I think you'll have no problem using your film at box speed.

[Michael Hiles]

I makes tests. I want and ASA that requires Zone 1 (4 stops below the meter reading) to produce a density of 0.1 on the film, using MY camera, meter, film and developer. This test is simple and unambiguous. And it works. YOUR meter, camera, film and developer may produce a different ASA to deliver 0.1 density on the film. So your situation is different. The difference is the meter (mainly), camera (perhaps a little due to shutter variations), and developer. Make orderly tests. The rest is speculation, since YOUR gear is not MY gear.

[kenneth]

Ansel Adams' advice is only really relevant today if you are processing your individual frames individually.

 

On the assumption that you process a whole roll at a time, the advice may be different.

 

I use Tri-X almost exclusively unless it's Pan F+ weather. I rate them at 320 ASA and 32 ASA respectively, and I cut the developing time by around 15%. This, in my experience, retains the shadow detail and stops the highlights blowing out in the vast majority of cases.

 

Now, Tri-X is a very forgiving film. I rated the front of a film at 1600 ASA in a dark room in the Schindler factory in Krakow last Autumn, and the remainder of the film at 320 when I got outside. The whole roll was processed as normal and I got useable negatives from the front and the back end.

 

 

]

That is really useful information Andy especially as I use both the films you mention. As you say Tri-X must be a very tolerant film to cope with using two different asa settings on one roll. As far as Pan-F is concerned, I use Ilfosol 3 and Ilford recommend 4m.30s so to cut that back would create a very short dev time. Could you comment on that and also, Tri-X, again I use Ilfosol 3 6m.30s which I guess could be cut back by 15%. By the way, yesterday I bought one of the new Gossen Starlite Meters which seems really excellent. I will report on how it performs. It has also helped me get my head around Zone System. £329.00 dale Photographic in Leeds

 

http://www.gossen-photo.de/pdf/flyer_starlite_gb.pdf

[kenneth]

By using an ASA different than the one quoted by the manufacturer your a tailering the ability of the emulsion to record a certain range of tonal values to the tonal range of a scene. Not all scenes have the same range of tones. A snow scene in bright sunlight has a very wide range of tones and what one usually does is to underexpose this type of scene or tonal range and then tailer the development of the film to capture as best the tonal range of the scene. Scenes with low contrast, typical of s scene at night are usually underexposed and the development time increased to bring out the toanl range on the film. Learning the various Zone systems will help you understand the mechanics but you must also be able to control your own devlopement times. I read where someone said you could use a simplified zone system without development modifcation but I never used it that way because I always shot my film for a specific situation.

Good luck it will take time and effort but your prints will be superior.-Dick

 

Thank you Dick. You mention the Zone System which I have read in AA's book Negative. It took a little to get my head around it but yesterday I bought a Gossen Starlite Meter and suddenly the clouds cleared and I gained much more awareness of the mechanics that you refer to. It is wonderful that there is so much to learn even after 46 years making pictures

[andybarton]

That is really useful information Andy especially as I use both the films you mention. As you say Tri-X must be a very tolerant film to cope with using two different asa settings on one roll. As far as Pan-F is concerned, I use Ilfosol 3 and Ilford recommend 4m.30s so to cut that back would create a very short dev time. Could you comment on that and also, Tri-X, again I use Ilfosol 3 6m.30s which I guess could be cut back by 15%.

 

Can't comment on Ilfosol, since I have never used it. I use HC-110 now. VERY economical, very flexible and gives great results. If the development times get too short, it's possible to dilute the stock mix further, to increase the times.

 

I can't imagine sitting there inverting for 36 minutes... you must have the patience of Job.

[kenneth]

Can't comment on Ilfosol, since I have never used it. I use HC-110 now. VERY economical, very flexible and gives great results. If the development times get too short, it's possible to dilute the stock mix further, to increase the times.

 

I can't imagine sitting there inverting for 36 minutes... you must have the patience of Job.

No Andy 6min. 30secs Tri-X and 4min.30secs- Ilfosol 3 Pan-f

[tobey bilek]

I have yet to find a Kodak or Ilford or Fiji film that did not for me produce the required separation in the dark tones of a grey scale. I use a standardised target strobe lit so weather does not matter.

 

ISO is set by internation standard by having a certain density in dark shadows measured with a densitometer. My grey scale test is as close as I can get and that is really all that matters. How it works for you.

 

Now if you want more shadow detail, cut the ISO in half and reduce the development time 20%. That neg will print the same as 100 % iso at your normal time.

 

The ISO standard also calls for a standard developer, D76. A speed increasing developer or a fine grain developer upsets the standard and may require the film speed be adjusted.

[kenneth]

Ansel Adams' advice is only really relevant today if you are processing your individual frames individually.

 

On the assumption that you process a whole roll at a time, the advice may be different.

 

I use Tri-X almost exclusively unless it's Pan F+ weather. I rate them at 320 ASA and 32 ASA respectively, and I cut the developing time by around 15%. This, in my experience, retains the shadow detail and stops the highlights blowing out in the vast majority of cases.

 

Now, Tri-X is a very forgiving film. I rated the front of a film at 1600 ASA in a dark room in the Schindler factory in Krakow last Autumn, and the remainder of the film at 320 when I got outside. The whole roll was processed as normal and I got useable negatives from the front and the back end.

 

Andy, Then can I ask what may sound like an obvious question. The old adage used to be- meter for the shadows and develop for the highlights- which seems to make sense. Using downrated ISO numbers like you suggest. Would I still follow this or just take an average meter reading of the whole scene- thank you

[andybarton]

Works for me (I don't own a spot meter)

 

At least, I think it does.

 

Have a look at my Tri-x and Pan F+ galleries here to judge for yourself

[kenneth]

Works for me (I don't own a spot meter)

 

At least, I think it does.

 

Have a look at my Tri-x and Pan F+ galleries here to judge for yourself

 

I would say it does Andy. Just printed up some Pan-F today with some very pleasing results. I have also taken your advise and adjusted the ISO settings on my M6's- 320 asa Tri-X and 32 asa Pan-F Plus. Thank you

[budrichard]

One last comment, bracket, bracket, bracket. Unless you are shooting 'spot' news or sports and no one uses film for that today anyway, bracket depending on how important the picture is to you and how difficult you precieve the lighting. Its not unusual for me to bracket +- 2 stops in min 1/2 stop increments to assure myself of a usable negative but that is because in the age of film, you had to assure yourself that you brought back a usable shot. One time in front of disgruntled City Editor because you didn't get a usable negative and the City Editor had to use a stock AP or UPI photo, is a lifetime lesson.-Dick

[Mark Pope]

I read various articles by the likes of Ansel Adams and Barry Thornton about underrating B&W film and not working to manufacturers ratings. Some say by 30%, others by as much as 50%.

 

 

I can only assume the reason for this is the tendency on camera light meters to give 18% grey scale readings which in alot of cases is too high when an overall reading is taken. However, if you point the camera or light meter at the area with the shadow detail you wish to expose as visualised there shouldn't be a need to down rate ISO settings should there?

The reason for underrating the film is to make sure that there is sufficient shadow detail recorded when the exposure is made. It's actually got nothing to do with the behaviour of the meter.

However, when you meter off the shadows, if you don't then make a compensation ,then they will be placed on zone V, which equates to 18% grey. Shadows with hints of detail are generally placed on zone III, which is 2 stops below zone V. So, to get the correct exposure, you need to reduce the exposure by 2 stops - for example, if the meter reading for the shadows was 1/30 at f8, then make the exposure at 1/125 at f8. A spot meter is useful for this. However it really comes into its own when you take a shadow and a highlight reading so you can see where the highlights will fall when you make the exposure.

 

The other aspect to consider is development. The basic tenet for the zone system is "expose for the shadows, develop for the highlights". Development or development time will determine the density of the highlights and the idea here is to develop the film so that the highlights aren't blocked out. This is known as normal development or 'N'. When you know your Normal personal development time, you can then do further testing so you can alter the characteristics of the film to cater for different subject brightness ranges: so-called N-1, N+1 development. N-1 means compressing the subject brightness range by 1 stop - so highlights that would have fallen on say zone IX would end up on zone VIII (hints of highlight detail). N+1 expands the subject brightness range by one zone. None of things will affect the shadow detail.

 

So, if you were so inclined, it would be necessary to do a lot of testing which gets a bit tedious in my view.

 

I would be interested in hearing others comments on this concerning different film stock.

 

I personally have now standardised on Ilford Pan-F 50asa and Kodak Tri-X 400asa setting the manufacturers ISO ratings on my M6 bodies and opted for selective area meter shadow detail metering with the M6's built in meter. Leica refer to the meter in an M6 as a fat spot meter which I assume means that it is trying to be all things for all men.

 

My standard film stock for LF work is currently HP5 plus which was rated at EI 200 and developed in Perceptol 1+2 for 12 minutes at 24 degrees C - as per the recommendations in Barry Thornton's book 'Elements' which I believe is no longer in print.

I did a bunch of testing, but it just confirmed Barry's recommendations!

 

For 35mm work, I rated HP5 plus at EI 320 and usually developed in ID11 1+3 for 18 minutes at 21 degrees C. This gave me nice easy to print negatives that generally gave a good print at grade 2 or 2 1/2 on Ilford Multigrade paper.

 

Of course, everything probably changes if you are scanning negatives - I have no idea how one would go about determining the correct EI and development times for scanning. Though I guess you would still want a neg with plenty of shadow and highlight detail.

 

I guess the other consideration might be a spot meter to meter shadow areas more accurately.

I thought you had bought a spot meter - unless this thread pre-dates your spot meter thread?

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[kenneth]

Thank you Mark and yes my original post predated my purchase of a Gossen Starlite which seems very good. I will comment further when I have processed some results. I am also following the guidance given here rating Tri-X 400 at 320 asa and Pan-F Plus 50 at 32 asa and I will reduce my development time by 15%

[Mark Pope]

Thank you Mark and yes my original post predated my purchase of a Gossen Starlite which seems very good. I will comment further when I have processed some results. I am also following the guidance given here rating Tri-X 400 at 320 asa and Pan-F Plus 50 at 32 asa and I will reduce my development time by 15%

That will be a good start - don't forget to meter off the shadopws where you want hints of detail then reduce the exposure by 2 stops to place it on zone III. Should be a piece of cake after that...

 

Cheers

 

 

Mark