Archived posting to the Leica Users Group, 1997/09/30
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 00:52 30/09/97 +0100, you wrote: <snip> >>I believe the blue filter trick is as follows: Nearly all of the really >>good enlarging lenses are f/2.8. This is necessary for critically sharp >>focus as it eliminates depth of field. If you use a 2.8 enlarging lens >>wide >>open with a grain focusser, the image is too bright. Hard to really >>critically focus. If you stop down to reduce the intensity, you now are >>dealing with depth of field and cannot really get the exact image plane >>critically sharp. By using a blue (monochrome viewing filter, Kodak >>Wratten >>#90) gel in your focusser, you cut the light intensity and build contrast >>in the grain image you are viewing. Easier to focus critically sharp. On >>some enlargers, the #90 is too dark. Use a level of CC-BLUE that works for >>you. Some enlarger heads, such as the ZBE Starlight head, can put out >>enough light to drill a hole in your eye via the focusser. Almost needs >>two #90 filters. >>Jim One question- if the enlarger has colour filtration built in or will take filters, is there any disadvantage to using that instead of a blue filter on the focuser? Joe Berenbaum