Developer dilution and exposure question

Xícara

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Hello,

I've been experimenting with x-ray film (Fujifilm UM-MA) and have found an ISO/developer dilution that gives negatives of a good density and with a development time of around 10 minutes. Specifically, I'm exposing at ISO 16 and with a 1+4 dilution of D76H (non-hydroquinone type of D76 dev).

There are many situations where I would prefer to shoot at a higher ISO. If I decrease the developer dilution (eg. to 1+2 or even 1+1), raise the ISO (eg. to ISO 64) and adjust the development time accordingly to get an adequate density in the negative, what qualitative changes am I likely to see in the negative, ie. in terms of contrast and grain or other aspects?

Thanks,
 

Milpool

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If you decrease the dilution of the D-76 type developer as you propose, and develop the film to the same gradient, you can normally expect directionally finer grain and decreased sharpness. Whether or not these differences are visible depends on how big the change in dilution is, and of course magnification. There will most likely not be a significant change in curve shape or emulsion speed.
 

koraks

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Xícara said:
development time of around 10 minutes. Specifically, I'm exposing at ISO 16 and with a 1+4 dilution of D76H (non-hydroquinone type of D76 dev).
Click to expand...

Sounds like you're building a lot of density - or maybe your D76 variant isn't quite as active as the regular one. Anyway, if it works for you, that's great.

If you expose at a higher EI, you'll reduce shadow detail. How you develop it, doesn't matter a whole lot.

When I regularly shot xray film, I exposed it at EI50 and got decent results in terms of shadow detail. I developed in whatever I had at hand; mostly tray development by inspection. I never worried about grain much because it was large format and much of it I used for contact printing to begin with. I did scan from time to time and found the results relatively grainy unless I used Ektascan B/RA mammography film, which was reasonably fine-grained; a bit like Fomapan 100 or so.
 

xkaes

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As already mentioned, increasing the ISO is basically under-exposing the film somewhat. That typically means over-developing the film -- which increases the contrast. Whatever approach you take will result in more contrast, but some developers/dilutions/methods may impact the grain.

In your situation, the solution is easy -- but time-consuming. Take a few tests shots at ISO 50, and develop them as you might expect (or as others advise). If the results are OK, you are all set. If they are too contrasty or grainy, take another set of shots and adjust the development (change the developer, dilution, time, method, etc.). Rinse and repeat.
 
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Xícara

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Thanks for the replies everyone. That's very helpful. I did actually originally rate the film at ISO 64. I got nice results, but at a 1+4 dilution the film took ages to develop (more than 20 minutes). I also left the negatives much thinner than I would have liked, purely due to lack of patience.

UM-MA film (a mammography film) has single-sided emulsion which might explain the longer than normal development times, compared to other double-sided x-ray films.

I'll do some more tests at ISO 64 (or 50) and see how it goes with a stronger developer solution. It's good to know now what I need to look out for.

I've not yet printed any of my tests, since I don't yet have a medium format enlarger (only 35mm). I have digitised the negs, but I don't think I can post any examples here due to the hybrid policy.

All the best,
 
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koraks

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Xícara said:
but I don't think I can post any examples here due to the hybrid policy.
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It's fine, really. Please feel free to post them; so far nobody has ever complained about people offering digitized illustrations in the analog forums.

Given the long development times I'd definitely use a less dilute developer, yes. It's been a while since I did any pictorial stuff with xray film, but only remember relatively short development times, even for the single-sided B/RA film. Maybe the film you use is hardened more, or has a firmer supercoat, which would make it develop a lot slower.
 

MattKing

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koraks said:
It's fine, really. Please feel free to post them; so far nobody has ever complained about people offering digitized illustrations in the analog forums.
Click to expand...

Even in APUG days this was okay - the site has always permitted scans from negatives, as long as the post-processing was reasonably minor, and of the type that one might do with an analogue print (cropping, adjustment of exposure and contrast, restrained dodging and burning, and similar).
And for discussions like this, a backlighted digital photo of the negative itself is very useful.
 
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Xícara

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Thanks. Here are 4 photos exposed at ISO 64. Development times were at least 16 minutes. Negatives were fairly thin but digitised well with a DSLR. Photos taken with a Mamiya C330 with a single exposure back. All photos exposed using an incident light meter:






The next three negatives had good density and the film was exposed at ISO16. All photos exposed using an incident light meter:





Despite the thin negatives, the ISO 64 shots stand up pretty well, I think. Perhaps exposing at ISO 64, and with a stronger developer solution, might be the way to go.
 
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xkaes

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If, as you say, the ISO 64 negatives are thin, then they are under-exposed. Increasing development -- in whatever way -- will just increase contrast. If you want normal contrast, you need more exposure and less development.
 

loccdor

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The ones exposed at 64 look very pleasing to my eye.
 
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Xícara

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I prefer the ISO 64 shots too, but they may just be better photos/subjects, rather than the process being at fault. Here are two of the negatives - shoes at ISO 16, hat at ISO 64 - (photo taken with an android phone - and not using a proper light table) showing the difference in density.



On the weekend I'll do a couple of tests comparing low ISO/dilute developer with higher ISO/stronger developer, on the same subject.

Cheers,
 

loccdor

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If your end aim is digitization the 64 should work fine, 32 or 16 if you plan on analog printing.
 
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Xícara

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Hello,

I did a test yesterday. Took two photos of a stand of buriti palm trees by a lake (the same location as in the palm photo above), both with a yellow filter (compensated by a stop) to try and darken sky and water. The first photo below was shot at ISO 16 and developed in a 1:4 dilution of D76H for approximately 9'30" (I kept time by counting!). The second photo was taken 5 or 10 minutes after the first (and the sun was rising) at ISO 64 and with a developer dilution of 2:3 for approximately 8'30". This should have been developed for less time, as unfortunately the negative came out a bit denser than the ISO 16 shot. But it wasn't overly dense. I'll also include a mobile phone photo of the scene with camera.





On Flickr, the ISO 64 shot was more popular (I suspect because the foreground was lighter), however my preference is for the ISO 16 shot, mainly since the water has a more natural tone. Using Darktable as my photo editor (and not burning any region in), I couldn't darken the water without darkening the palm leaves too much. So I guess the ISO 64 shot has a heavier contrast.

Would that higher contrast be due to the lesser exposure/strong developer solution or would the denser negative have contributed?

Cheers and a good week to all,

Edit: The smudginess of the sky in the ISO 16 shot is strange. There were extremely fine wispy white clouds not visible in the mobile phone shot. Might this be from uneven development? I know some people agitate constantly in the development of x-ray film. I did so every 30 seconds with continuous agitation for the first 30 seconds.
 
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RalphLambrecht

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I agree with the last sentence but think that grain will increase due to longer development times
 

Vaughn

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When does the concentration of Sodium sulfite come into play? A stronger developer (decreased dilution) will have a stronger solution of the silver solvent (Sodium sulfite) and thus have a stronger action dissolving/softening the edges of the silver grains...especially with longer development times.
 
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