Help analysing results of Tri-X reversal, please

[mr.datsun]

Thanks for the explanation. I don't understand the chemistry too well but get the principle. I'll give this a go once I can get some sodium thiosulphate.

I didn't know about the Scala 200X. That's a quite exciting prospect as it has a good reputation amongst still photographers as a reversal film. I see Wittner recommend rating it at 100ASA and using D94a.

If working in Super 8 pays off for me then I'll consider investing in a bulk system.

Tofek, where is the best forum for discussing Super8?

[Tofek]

The forums I know of are filmshooting.com , cinematography.com and super8.es (the most complete about reversal processing, though in spanish ), filmvorfuehrer.de (even worse, in german).

[mr.datsun]

thanks tofek. I tried joining filmshooting.com a little while ago. I'm waiting for a response. I'll check out cinematography.com, too.

[Mike Wilde]

When I am calbrating an unknow film (and I do this semi often - on found films in bulk loaders I buy, etc). I expose them to a reflective step wedge test target in a copy camera, to determine the minimum effective exposure to overcome base and get image content off of the toe of the H-D curve.


Then a transmission step wedge is useful.

I use the step wedge in a slide copier where the light source is daylight to fine tune developer times.

For reversal, thiocyanate into the first developer has always worked best for me to get rid of the overall grey haze.

[mr.datsun]

When I am calbrating an unknow film (and I do this semi often - on found films in bulk loaders I buy, etc). I expose them to a reflective step wedge test target in a copy camera, to determine the minimum effective exposure to overcome base and get image content off of the toe of the H-D curve.


Then a transmission step wedge is useful.

I use the step wedge in a slide copier where the light source is daylight to fine tune developer times.

For reversal, thiocyanate into the first developer has always worked best for me to get rid of the overall grey haze.

Mike. Good advice. I'd never heard the term step wedge but, yes, I had been thinking of printing a zone system strip in the darkroom to use in order to a get a better calibration, especially as I also use a Weston meter. I guess this is the same as a reflective step wedge. But I wonder, can such a reflective 9 step wedge be bought cheaply in the UK? I now see that there is a nice looking thing called a Stouffer 9 step wedge but they do not seem to be available here.

[Mike Wilde]

My reflective step wedge target is found in an old Kodak darkroom data guide.

It is also posible to work from instructions in the 'Way Beyond Monochome' book of Ralph Lambrecht and make your own target on photo paper.
Basically you work systematically increasing expoisures on a sheet of paper under the enlarger with no neg in the carrier with one inch strips progressively being uncovered between exposure intervals.
The page of instructions is somewhere at home.

If you are really serious about honing your craft, Ralphs book is an extremely useful reference that you can read many times and still learn and get ideas from.

[mr.datsun]

hi mike. thanks for the ideas. I've banned myself from buying books so I think the self-made strip will be fine for my purposes .