In Ilford's datasheets they suggest either a 1-filter or 2-filter method for the levels of contrast on a dichroic head. The 2-filter method is supposed to keep your exposure times contstant all the way through 0-4.

Does this work in practice? Or is it just better to stick with the 1-filter method and know that after about 3 1/2 you need to double exposure times? FYI, I am using a Saunders/LPL 670DXL with Ilford VC RC paper (eventually FB too).

Thanks Roger

-- Roger Bird (rpbird@home.com), April 05, 2001

Answers

The two filter method works quite well provided you believe the data sheets that Ilford supply. If you are using a Saunders/LPL enlarger then I believe that the filtration will be Kodak (as opposed to Durst or Agfa). I am not sure whether the dual filter settings apply to Kodak filtration. The best thing to do is to use the settings initially to get some idea of the contrast available and then fine tune them to get the contrast you want. Grade numbers are only an indication after all. For convenience if you intend to do mainly monochrome it may well be better to trade the colour head in for a multigrade head. You will find exposures much shorter and will find fine tuning much easier as you only have one dial to worry about.

-- Adrian Twiss (avtwiss@ukonline.co.uk), April 05, 2001.

First, the exposure change at grade 3.5 is not a function of the paper. It is a function of the VC filters one can use, say, with a condensor head. If you use the 1-filter method with a dichroic head exposure will change with every filter setting, not just above 3.5. The manufacturers suggest filter settings for the 2-filter method but you can expect to do some testing and tweeking. I suggest you do the one filter method, forget about constant exposure and use test squares instead of test strips, as I explain here.

-- Tim Brown (brownt@flash.net), April 05, 2001.