FAQ Split Filter Printing.
Making fine prints with today's Materials
One of the most ignored aspects to Multi contrast papers is the ability to use more than one filter to make a print. As the main paper manufacturers are now cutting back or reducing the varieties of fibre based papers that they offer, a good understanding of how to exploit the current crop of Multi Contrast papers is essential. As a resource for further research I highly recommend Steve Anchell's book, 'The Variable Contrast Printing Manual' pub Focal Press 1997.
Multi contrast papers are are relatively recent innovation in the world of Black and White photography. It was first thought to have been introduced to the world around 1940 the idea had existed for a lot longer since 1912 but the then current crop of emulsions could not support it Frank F. Renwick a scientist at Ilford. 1
Multi-grade papers didn't really catch on when they were commercially introduced, they were considered 'inferior' to the more established graded fibre based papers. As someone who has only used modern fibre based papers I can't offer an opinion here.
My favourite papers when they were available had characteristics that I exploited with my film exposure and processing. I felt these graded papers were superior especially given my overall approach to printing both papers and developer. However during my recent Masters project I discovered to my horror that Agfa has stopped making my favourite paper, 'Portriga Rapid'. This means that I'm now going to have to think about using Multi-contrast papers.
The best way to 'exploit' the papers then is to use more than one filter to print them. There are several ways to do this, all have one thing in common though. The filters need to be in a position where they are easily accessible. This is usually under the lens a word of warning keep the filter as close as possible to the lens to avoid possible image degradation cause by dust and scratches this then means at any point the filter can be changed with out disturbing the negative in the enlarger.
The most simple and direct way to use more than one filter in printing is to use a higher or lower number to burn in areas locally in the print. For example, you can lower the contrast of the sky in an image by 'burning in' using a lower numbered filter than the one used to make the print. Or conversely you can burn in the shadow areas with a higher contrast filter to make the shadows more contrasty.
A more complex approach is to combine both the highest filter and the lowest filter, to add more versatility to the whole process.
Here's how it works.
First place your highest number filter in your filter draw, say a number '5' filter. Place your paper in the easel and do a series of test times across the paper. Next change the filter, leaving the paper in the easel. Put in the lowest filter in the pack. Ilford make a '00'. Now do another test strip this time expose the paper at 90 degrees to the first test. Process as normal and examine the print.
You should be presented with a print that has a dark and overly contrasty appearance on one corner, and the opposite on the adjacent corner. Counting across the paper in one direction pick the time that best suits your intention. From that time count the other exposure time for the other filter. This combination of times will be your next test strip.
What this means is this, say you counted across five exposure times on the test strip in the 5 filter direction, and they were 5 seconds each. This gives you an exposure time of 25 seconds with filter 5. Say you liked the 30 second exposure time for the '00' filter this means that when you return to the darkroom and do your next test strip it will have an exposure time of 25 seconds on filter '5' and 30 seconds on filter '00'. If you are pleased with the results, proceed, however, and this where the advantages of this paper real kick in, try another exposure time at say 20 seconds on filter '5' and 35 on filter '00'. This will give a different contrast to simply lowering the filter from 2.5 to 1.5 for example. Split filter printing will not create any contrast that the paper cannot. What it will allow is precise control over the values in the print.2
1. Focal Encyclopedia.
2. 'The Variable Contrast printing Manual' by Steve Anchell pg 93