B&W printing filtration with Old cold light head & 40cc yellow filter

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Just picked up an old Beseler 5x7 enlarger to go with the used Schneider(Durst) 240 componon so I can enarge some of my 5x7 negs. I have a 40cc yellow filter in the head with the cold light tube and in using my Ilford polygrade filters in Forte paper seem to be getting nice changes in contrast as I change filters. Anyone out there with experience on this setup to let me know if I will hit any major glitches, inconsistencies or problems as I get printing more with this setup?

-- Dan Smith (shooter@brigham.net), March 09, 2000


You'll face a couple of problems which will require calibration. First, the cold light is more blue heavy and will give you harder contrast than a regular tungsten source (which is what the filters are designed for) will give you. Second, the contrast grades will be unevenly spaced with the harder contrasts bunching together. There will not be less difference between grade 4 and 5 than there will be between 0 and 1. Typically the yellow or green filtration will help in trying to adjust the colour of your light source but will reduce the light output since the filter absorbs some light. An associated problem is that since the contrast grades bunch together at the high contrast end, you'll find longer holes at the low contrast end. This can be fixed by using additional yellow filtration to patch these holes and get the intermediate levels of contrast.You can calibrate your setup by printing test strips. You can get test strips from Stouffer (www.stouffer.com) or from darkroom innovations (www.darkroom-innovations.com). Project these strips and see what filter gives you the equivalent of a graded paper of your choice, say 2. I use an old Omegalite cold light and a #1 filter which gives me roughly the equivalent of a grade 2. So I just go ahead and use that without any additional filtration. The only filtration I use is when I want to get an intermediate level between 0 and 1 and 00 and 0 (which is a really long hole). There's information at www.ilford.com under multigrade regarding this and I think Howard Bond wrote some articles about this (maybe in Photo Techniques). Hope this helps. Feel free to email me if something is unclear. DJ

-- N Dhananjay (ndhanu@umich.edu), March 09, 2000.

You can also call Aristo. The technician there is very knowledgeable. Their web-page is WWW.ARISTOGRID.COM.

-- neil poulsen (neil.fg@worldnet.att.net), March 10, 2000.

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