Kodak Tri-X 400 Exposure Test

[Stealth3kpl]

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From UK Film Lab

http://ukfilmlab.com/2016/04/03/black-white-film-exposure-test-comparisons-kodak-tri-x-400/

 

Pete

[gbealnz]

Cheers Pete,

A good read, enjoyed it immensely.

Gary

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[Michael Hiles]

This piece reflects what has been shown by years of tests using Zone system techniques. Tri-X is optimal at ASA 200 - i.e. 1 stop over exposed relative to box speed of 400.

[Michael Geschlecht]

Hello Everybody,

 

The people who did the test could have saved themselves a lot of bother if they had simply read the Dx code on the film cartridge.

 

It say: " 3 stops over exposure latitude & 1 stop under exposure latitude with normal development as per the ISO written on the box".

 

Which means that the "optimal" film speed is ISO 200/24.

 

Best Regards,

 

Michael

Edited April 4, 2016 by Michael Geschlecht

[Stealth3kpl]

It's interesting that many people seem to feel Tri-X should be exposed at 320.

Pete

[Keith (M)]

It's interesting that many people seem to feel Tri-X should be exposed at 320.

Pete

 

That is what I do, (with dev time reduced by 15%) on the basis that it results in negs that are easier to scan.  It was interesting to note that:-

 

Film was developed in Kodak xtol, for ISO 400 (i.e. no push or pull)

[AlanG]

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This is a scene with a very low brightness range. If you expose at ISO 200 and process it normally the film curve will not be the same as one with an ISO of 200.

[AlanG]

Sorry I miss-typed and should have written ISO 400 at the end. I meant that if you expose at EI 200 (one stop over the ISO number of 400) the film curve (sensitometric measurement) will not match requirements in shape for an ISO rating. 

 

A low contrast scene can be shifted pretty far up or down on the flat part of the film curve via exposure change and still have pretty much the same look when printed.  But to better understand visually what happens with over and under exposure relating to an ISO number, a "normal" scene should be used.

 

This kind of stuff was well documented ages ago.

Edited April 4, 2016 by AlanG

[Michael Geschlecht]

Hello Alan,

 

The criteria for Dx coding are: For a subject in a "normal scene" which should then be processed with the standard development that is suggested for that film when that film is exposed at the ISO on the film box.

 

That is why Kodachrome 64 had a Dx coding saying it should be exposed within a range of: Not more than 1/2  stop on either side of its box speed. Which means it should be exposed at a speed as close to the box speed as possible.

 

Best Regards,

 

Michael

[NB23]

Over expose and lose all the bite. Tri-X is so widely loved for 2 reasons, IMO: 

 

1: Because of the look it gives.

2: People expose it at 400, which drives us to number 1 above.

 

HP5 has a the opposite problem: People say it's too gray and dull. But once exposed at 800 and 1600, that film really becomes gorgeous!

[AlanG]

Hello Alan,

 

The criteria for Dx coding are: For a subject in a "normal scene" which should then be processed with the standard development that is suggested for that film when that film is exposed at the ISO on the film box.

 

That is why Kodachrome 64 had a Dx coding saying it should be exposed within a range of: Not more than 1/2  stop on either side of its box speed. Which means it should be exposed at a speed as close to the box speed as possible.

 

Best Regards,

 

Michael

Got it but I'm not sure why Dx coding is relevant. Dx is only a barcode that sets the meter to the ISO so that you don't have to do that manually.

 

There are huge amounts of data of what happens with various b/w films in different exposure/processing situations which can then be applied to get what you think will be best for a given scene.  And we all vary in what we consider to be "best."

 

That should be obvious to all. And I hope that it is also obvious that comparing a very flat scene at different exposure levels doesn't tell you much about the shadows and highlights.

Edited April 5, 2016 by AlanG

[sblitz]

Over expose and lose all the bite. Tri-X is so widely loved for 2 reasons, IMO: 

 

1: Because of the look it gives.

2: People expose it at 400, which drives us to number 1 above.

 

HP5 has a the opposite problem: People say it's too gray and dull. But once exposed at 800 and 1600, that film really becomes gorgeous!

Agreed, but when the work-flow is scanning the negatives into the computer, flat and gray with broad midtones is preferred (At least by me) -- I can always add bite, tough to take it away. Eastman XX at 200 has bite, and  I have pushed it one stop with good results.

[Michael Geschlecht]

Hello Alan,

 

Actually, Dx codes does more more than simply tell the internal meter what the ISO on the box says.

 

The Dx code does tell the meter what the ISO on the box says so the meter can then display this box film speed number for the photographer to see.

 

It also does more:

It also tells the camera how many exposures are on that roll. So the camera knows when to shut a motor off.

 

It also tells the camera the latitude of the film in that specific cartridge so that an electronic shutter can know when to internally adjust the ISO in which direction under certain circumstances.

 

Have you ever noticed that some M7 users on this Forum have said that under certain circumstances their M7's tended to produce better exposed images, especially with transparency films, than their other metered "M" cameras with mechanical shutters do?

 

Best Regards,

 

Michael

Edited April 5, 2016 by Michael Geschlecht

[AlanG]

Hello Alan,

 

 

It also tells the camera the latitude of the film in that specific cartridge so that an electronic shutter can know when to internally adjust the ISO in which direction under certain circumstances.

 

Michael

I don't understand what you mean by this.  We all know there are various circumstances why you would bias an exposure lighter or darker. 

[Michael Geschlecht]

Hello Alan,

 

In the late 1970's & early 1980's there was the development of reasonably inexpensive very accurate electronically governed shutters by a number of manufacturers.

 

These shutters opened the door to possibilities that were not available before.

 

In order to implement some of these expanded possibilities the Dx system was invented for identifying what film, with which parameters, was in a camera.

 

The Dx code establishes the parameters I identified above in my previous Post.

 

The reason for the latitude of available acceptable exposure is to allow the internal program to "shift" from the rated ISO under certain circumstances.

 

Example: Kodachrome 64 has a latitude of 1/2 of a stop above or below its rated ISO. This means the rated ISO should be used (by the camera) when making exposure readings. No shifting here.

 

A film like Kodak Gold 100 has an available latitude range of 3 stops of over exposure & 1 stop of under exposure. This means that if a scene is metered at its rated ISO, or 1 stop under, or 1 stops over, or 2 stops over, or 3 stops over & then exposures are made & that roll of film with the 5 different exposures in a row is given normal development, then: All 5 negatives should be able to produce pretty much equal prints when printed individually appropriately.

 

This is something that became a factor with the advent of "aperture preferred " & "shutter preferred" & later "program" mode cameras. Their electronically controlled shutters were responsible for a lot of really well exposed images. Unfortunately these same cameras were not always as effective at improving a photographers composition as they were at improving their exposure's accuracy.

 

Also, unfortunately, I have to pause At this point. I will continue with my explanation as soon as I am able to.

 

Sorry for the interruption.

 

Best Regards,

 

Michael

Edited April 6, 2016 by Michael Geschlecht

[A miller]

What this test doesn't show is the effect of "expansion" of Tri-X, which is very effective at popping highlights.  A little expansion coupled with a one stop push can add a nice edgy contrast with deep blacks and bright highlights.  

What works best for me is exposing at 800 and developing at 1250 (1.5 stop push)...

Some examples of the results...

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I don't believe that there is one right answer.  It is whatever concoction works for you.

 

I get sublime results from exposing and developing at box speed...e.g., 

 

 

[EoinC]

Stunning, Adam!

[sblitz]

Adam -- I have never really understood the point of pushing development 1.5 stops and then overexposing by a 1/2 stop???? Why not just shoot and develop at 800 or 1200 or whatever? 

[A miller]

Adam -- I have never really understood the point of pushing development 1.5 stops and then overexposing by a 1/2 stop???? Why not just shoot and develop at 800 or 1200 or whatever? 

the idea is that giving the film a little extra development time will increase the highlights to a disproportionately greater extent than it will increase the shadow detail.  So basically the "expansion" of the film by an extra 1/2 stop will increase the intensity of the highlights and not touch the shadow detail.  Combing this effect with the one stop push of the film's box speed will have the effect of increasing overall contrast but in a way that gives a little extra pop to the highlights. 

This approach is most effective in medium to low contrast scenes - not scenes that already have high contrast. 

 

Ansel Adam's book The Negative has a good section on film expansion and contraction.  It is worth a read....

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[sblitz]

unless you need the light, then in a low contrast scene shoot Tri-x at 320 and 400 otherwise (assuming box speed is correct)....or shoot at 200 per the OP's comments and shoot at 120 in a low contrast scene?