FomaPan + HC-110 Characteristic Curve

Ian, I think it would be of more benefit to try to do this yourself. I don't know if you have researched a method, but I suspect it may require a transmission densitometer. These were very expensive a few years ago, but now they can be found quite cheaply. You are clearly interested in researching different film and developer combinations and optimising your processes. It's definitely the way to go if you want to produce the best negative quality for a particular application. I don't scan LF negatives, but I am guessing that it needs a specific type of negative, perhaps more so than traditional printing. I would suggest you check out a method for this, or any other combination you would like to try, and equip yourself to do your own tests. From a personal point of view, I don't think I would rely on someone else to do this for me. One other point to bear in mind is that you seem to produce pretty good pictures already, in my opinion anyway.
Alex.


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Ian,

I have been giving this some thought.

Having read the above I tend to agree with Alex in that you have to do this for yourself. If you farm this out it will not give the same results as you may get, for a variety of reasons. Everybody for example has their own method of agitation both in frequency and method, water quality differs across the country which may affect development, equipment differs and 20 degrees on your thermometer may be slightly different to 20 degrees on mine or whoever does the job for you. What happens is that we adjust our times and procedures to suit our method of working and equipment.

As Alex says a densitometer can be used to read negatives but you can also create the curve specific to you and your methods. As you scan your negatives and read them on your monitor you can take readings that would enable you to create the curve. I believe in PhotoShop there is a tab that shows the histogram of the scan but under the Information tab shows the percentage figure for the K (Black) value. it is there in the copy of Elements 12 that I have.

In a book called Way Beyond Monochrome by Ralph Lambrecht and Chris Woodhouse edition 2 they give typical values for the various Zones of the Zone System including the percentage values for a monitor. This can be found online at http://www.waybeyondmonochrome.com/WBM2/Library_files/TemplatesEd2.pdf second page.

My thought is that you expose a number of sheets (or find a method of creating the exposures on a smaller number of sheets but it gets complicated) in line with the Zone System principals i.e. each sheet (or part) receives one more stop than the previous one. You need to be able to identify which zone each sheet is exposed for. Develop all the sheets together so they get common development. Next scan each sheet with exactly the same scan parameters. Once done you can open each scan on your monitor and read the K value as a percentage. You may need to adjust your scan parameters to show the full range. These values can then be plotted to show a reverse curve but one that would tie in to the values shown in the document above. I am not sure if you would need to invert the scan to be a positive to match the values. Easy enough to do on a digital system.

I have not tried this but have plotted the values given and they look like a curve I would expect from a print read with a reflection densitometer. In order to get the curve you need to assign a log exposure value but that is easy. Zone 0 is 0, Zone I is 0.3, Zone II is 0.6 and so on adding 0.3 for each stop.

I tried to insert the curve I got but it is not in an allowed format. However you could plot it for yourself from the above values as a "standard".

It may or may not work for you but perhaps worth a try. However as Alex said I can see nothing wrong with the work you are producing now.

 

I can't comment on HC-110 as I've never used it, but the pdf data sheet for Fomapan shows curves for different development times in the same developer (in this case, Microphen) and the curve shape alters depending on the time, going from a more or less straight line to an "s" curve at longer times.

 

Depending on whether your glass is always half full or half empty, you could read the upswept curve as indicating greater tonal separation in the highlights - provided that your scanner (in your case) can deal with the densities.

 

There is always the possibilty of using a chemical reducer. They come in two basic types - those that shave off the same amount of density from shadows and highlights, and those that work most on the highlights. I don't know off hand if any are commercially available now (I still have a 1/3d Johnson's Pactum of Farmer's reducer somewhere) but formulae are readily available.

 

Farmers reducer is available from AgPhotographic and others manufactured by Fotospeed. It looks like there are 4 sachets in the pack each to make 250 ml.