Foma Fomapan 400 H+D Curve with Replenished XTOL for 8:45 at 24C in a JOBO

Adrian Bacon

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For reference, and if anybody wants to discuss.

I've made these exposures as carefully as I could and eliminated as many variables as I realistically could. While it is not scientific, and certainly not up to ISO or probably manufacturer standards, it is as accurate as I can make it with what I have available to me, and certainly accurate enough that I thought it would be share-worthy.

Each of the curves is from film base plus fog up to a correctly exposed 18 percent grey card in full stop increments using a studio strobe, and transmission rated lens set to infinity focus. The strobe was incident metered to 1/10 stop and varies less than +- 0.1 stops shot to shot. The intensity of the light to the film plane was controlled with the lens aperture, so once the strobe power was set, it did not change for the duration of the exposures. The 18 percent grey card filled the frame so there shouldn't be any flare.

The densities were measured with an X-Rite Densitometer.



In replenished XTOL in a JOBO at 24C with continuous agitation, I couldn't get better than ISO 160. The flash I was using has a t.1 duration of 1/900 at full power and 1/300 at minimum power so I was within the reciprocity failure of the emulsion.

Pushing to 10:00 at EI 160 has almost no change on the bottom end and only gains ~0.1 more density at the top, but still totally shoulders off. The exposed tongue of the film never exceeded 1.72 above film base plus fog at 10:00 development time.

Other than that, I'm not particularly wild about the shape of the curve, but it's roughly representative of what Foma has published in their tech sheets, at least in terms of shape, though they seem to be able to get a lot more density.
 

MattKing

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Adrian,
Just musing here, but have you considered putting these threads in the Resources section instead?
 
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Adrian Bacon

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MattKing said:
Adrian,
Just musing here, but have you considered putting these threads in the Resources section instead?
Click to expand...

I suppose I could. Can they be discussed there? In all honesty I haven’t really looked at the resources section. I just might be missing out on a whole pile of stuff.
 

MattKing

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Discussions do happen there - for better or worse!
 
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Adrian Bacon

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MattKing said:
Discussions do happen there - for better or worse!
Click to expand...

hmm... well, I do have a number of emulsions in the pipe that I’m doing this exercise on, I’ll look at potentially putting them there, though I guess I do risk less visibility. My goal was really just putting it somewhere that google would find if people were looking. I plan to have them on my website, but, here is a more generic place where discussion can happen.
 

MattKing

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Posts in the Resources section are indexed the same as in other normal sub-fora - it isn't like the Groups.
If, like many, you rely on the New Posts function, they will show up.
 

Lachlan Young

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@Adrian Bacon - I recall from the available published data, Foma suggests that Xtol runs out of steam in about the Gamma 0.75 range (at a claimed EI of about 225 I think) unlike Microphen or D-76/ ID-11 which seem to be able to develop more contrast. It's an OK film in actual use, though it isn't as sharp and the halation seems worse than more modern films.
 

Bormental

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FWIW, my results with Foma 100 and 400 in Xtol 1+1 using MDC times were not great (too thin). Instead of tinkering with it, I've placed Foma into my "D76 bucket of films". It's a quirky film but its quirks are great with D76.

We need "Adrian Bacon D76 Edition" here to do the god's work of testing films with D76 For those of us who haven't converted into replenished xtol religion for various reasons.
 

Bormental

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Lachlan Young said:
@Bormental - I've found that the MDC's relationship to the manufacturers' data to be at best extremely questionable.
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Sorry, I am not following. Foma 400 datasheet does not list times for Xtol 1+1, only for full-strength, so MDC was the only starting point available. Is there another PDF published by them that has more? I'm interested because I generally like Foma picture and want to keep improving at shooting it.
 

138S

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What is important is the shouldering by +4 overexposure, telling how this film has to be used, having to underdevelop if wanting linearity in those extreme highlights. I feel that shouldering can be interesting if accurately metering, to compress highlights to be printable.

I think it's interesting to also see the meter point position when rated EI 160 which is the right one, of course:






Lachlan Young said:
though it isn't as sharp and the halation seems worse than more modern films.
Click to expand...

It may be noticeable for 35mm film, but not much noticeable for MF and up.
 

grain elevator

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Cool, a real shoulder for once! I don't like the grain I see in samples, but the shoulder in the usually printed part of the curve could convince me to try it for certain things. People list the decreased contrast in the highlights as a benefit of staining developers, which is nothing else than a shoulder, but otherwise linear films are all the rage... I don't get that.
 

Lachlan Young

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Extrapolation from the available data - if it's not listed, average out what the percentage difference between stock and 1+1 times for multiple films in Xtol is & you'll often get pretty close. And in the case of Xtol, 1+1 times are often very close indeed to D-76/ ID-11 at 1+1 - and times for a range of D-76/ ID-11 dilutions are listed in the Foma PDF catalogue (as are the gammas those times reach).

138S said:
but not much noticeable for MF and up.
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It actually is noticeable at quite small enlargements (2x off 4x5) that Foma films are less edge sharp/ crisp than the more modern technology films (and halation does play a role in robbing sharpness). If the look works for what you want to do, don't worry about it. I actually like the Retro 320 film, despite all its quirks.
 
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Adrian Bacon

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yep, it does noticeably shoulder off. Looking at the actual negative, the top 2-3 stops are totally bleeding light into adjacent frames, so up there you’re completely overwhelming the halation layer.
 

138S

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Foma datasheet MTF plot starts falling from 10lp/mm, but I think that perceiving it at 2x it would be quite hard... It would be interesting to make a side by side, at least for LF lens MTF also falls from 5lp/mm so it would be interesting to see when there is a practical difference or not.

The 5x7" F100 negatives of a friend I've been developing look quite sharp even at 1m enlargement.
 

grain elevator

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Adrian Bacon said:
yep, it does noticeably shoulder off. Looking at the actual negative, the top 2-3 stops are totally bleeding light into adjacent frames, so up there you’re completely overwhelming the halation layer.
Click to expand...
Oh well, then not. Do all the Foma films use the same anti-halation layer and show this bad behavior in your tests?
 
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Adrian Bacon

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grain elevator said:
Oh well, then not. Do all the Foma films use the same anti-halation layer and show this bad behavior in your tests?
Click to expand...

I don’t know if they do or not. I’m currently working out speed and dev times for the 100 and 200 emulsions and haven’t yet hit them with 10+ over middle grey to see what they do up there.
 

138S

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grain elevator said:
Oh well, then not. Do all the Foma films use the same anti-halation layer and show this bad behavior in your tests?
Click to expand...

This is not such a bad ISO behaviour, some top notch protraiture gurus were shooting Tri-X 320 Pan at ISO 80 with incredible results. This is about mastering the medium, if you shot wet plates for a time then you'll find that any film has speed in excess .
 

grain elevator

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I wasn't talking about speed but about halation. That will only get worse if you overexpose.
Adrian Bacon said:
I don’t know if they do or not. I’m currently working out speed and dev times for the 100 and 200 emulsions and haven’t yet hit them with 10+ over middle grey to see what they do up there.
Click to expand...
Wait, halation only gets really bad 10 stops above middle grey? So you didn't show that part of the curve because it got so bad you couldn't measure density that wasn't influenced by highlights bleeding in?
I look forward to the comparison with the other Foma films (which I'm more interested in using). Thanks for sharing the results of all this work!
 

Lachlan Young

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@grain elevator You can see the halation on normal negs used in average situations - hill against sky for example. It's not massively obvious, but you do notice its effects on overall performance.

@138S The Foma films are not necessarily unsharp, they're just noticeably less crisp than all the films that are delivering 100+ % MTF response. This is a large part of why they look more old-fashioned. Some Foma films may not have significantly less resolution at extreme contrast than some more modern technology films, but their ability to contain and represent useful imaging information in low contrast areas is constrained by lower sharpness (halation plays a role here), higher granularity and a curve shape that shrinks useful latitude significantly. For example, 1950's FP3 in 120 will deliver an excellent 1.5m wide print (and full size multi-panel billboard), but it's very obvious that it isn't anywhere near as good as more modern films in the granularity/ sharpness/ latitude relationship. If Foma works for the job you need it to do, that's fine, just don't go making artificial hierarchies that ignore the very significant qualitative and quantitative differences between Fomapan and more modern technology films.
 

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A few generic comments on analyzing the shoulder of films.

1) The way a sensitometer works, the shoulder is exposed through the clear or nearly clear portions of the step wedge. In many cases, the light intensity is not enough to get to the shoulder without multiple exposures.
2) The toe of the curve is produced from the dense portion of the step wedge. Even with expensive carbon step wedges (vs photographic film based step wedges) they are limited in the maximum density to fit the whole series in the sensitometer's target area and yet still have steps large enough to be read by conventional densitometers. Usually 21 steps that are 1/2 stop apart (0.15 log d).
3) Put 1 and 2 together and one should see why a common H&D curve only shows the toe and cuts of the shoulder of most films.

Finally: A comment about my own experiences with placing portions of the scene on the shoulder. Although it seems like it might be a good idea to tame highlights, the prints look bad. I'll describe it as an analogy with an under-exposed negative.
As the curve becomes more horizontal, the separation between the zones becomes less, which is the opposite of what one wants.

An example: If one has three negatives; a) correct exposure for excellent print, b) severe under exposure and c) severe over exposure with portions of the image on the shoulder.
Print all three negatives so the darkest shadow is just black on the print, and the brightest highlight is just white on the print.

How do they look? The correctly exposed negative makes a perfect print with mid good mid tones (by definition). The under exposed negative makes a print where the mid tones are too dark. The over exposed negative (the one with portions on the shoulder) makes a print where the mid tones are too bright. It is an odd look and frequently not pleasing. I'd encourage people to try this to see what it looks like. Maybe it would be used in some special case.
 

NB23

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Great post, Mr. Bacon!

I’m presently on a printing spree of about 30 fomapan 400 films that were developed in rodinal (product called Blazinal in Canada).

I must say that I am very surprissd by the beauty of the tones and the grain.
I like my fomapan 400 with a BW 092 filter.

Here is an example, shot of a print soaking in hypo clearing bath


 

138S

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ic-racer said:
Finally: A comment about my own experiences with placing portions of the scene on the shoulder. Although it seems like it might be a good idea to tame highlights, the prints look bad.
Click to expand...

What ?

Look, all the zone system literature is based in taking advantage from toe and in the shoulder to compress shadows and highlights when necessary.

No mistery, a paper only displays 6 stops and a half. Mids require an standard gradient on paper to not look dull, and the excess dynamic range the scene has can only be compressed to robe some range in the 6.5 stops the paper has.

The problem happens when unsing a linear film like TMax, highlights are to skyrocket to unprintable values if special print manipulation is not used.

Zone System basicly teaches how to place scene spots in uncompressed or in compressed zones, this what Adam's The Negative and The Print explain. All that pool of amazing classic work is based in exploiting toe and shoulder proficiently.

Yes... the John Sexton way is making a TMax linear capture to obtain a flexible negative and later manipulating what necessary to place the scene DR on the limited paper DR, at the end a wide DR scene needs compression to fit in the paper inferior DR, you do that more in the metering+processing or you do it more in the printing, those are different approaches, but no way is better or worse.
 

ic-racer

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The toe and shoulder are horrible placed to place important image information if one wants a good looking print. Of course if one is doing 'something special' or unusual, anything goes.
Compressing on the shoulder makes bad looking prints. You may be misunderstanding something you have read. That is ok, I teach for a living and can post some links to useful information about film's response to exposure and development.
 
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