Walter, I am not sure you are correct in your description. Consider what each filter does, remembering NO FILTER corresponds to grade 2, but as the filters are designed to work with a uniform exposure time (from 0-3 1/2 grades) there must be some neutral density as well as the yellow or magenta filtering to maintain the same exposure times. Low contrast filters use yellow, to filter out the magenta, so adding No 1 plus No 2 filters gives the neurtal density filter (2) plus some yellow (1) resulting in the same amount of yellow filtration but a longer exposure required, i.e. still equivalent to a No 1 filter. Combining filters with numbers below 2 (yellow) and above (magenta) basically add neutral density requiring longer exposures, with the filter allowing most of its colour through controlling the contrast. If you tried combining filters 0 and 1, you are reducing the magenta further, but if the 0 filter already excludes all magenta then the addition of filter 1 will have no effect, other than increasing exposure. Trying the same with filters in the range 3-5 is more complicated, as from 4-5 there is a required increase in exposure time needed for the paper. My reference to filter 2 being equivalent to no filtration is based on the Ilford Ilfospeed Multigrade II book. However, as others have mentioned, there are techniques of printing different sections of the print using different filtration to perhaps increase the contrast of just the clouds in the sky, or of split grade printing which uses exposures of Filter 0 to bring the paper to a "threshold point" and then a higher grade to improve highlights. One reference is the book by Harry Fearn, "Better in Black and White" ISBN 1 873319 30 4.I may be able find some further references if needed. But if unsure, experiment, and have fun. Jim Thyer ----- Original Message ----- From: "Walter Holt" <locnleave@xxxxxxxxxxx> To: "List for Photo/Imaging Educators - Professionals - Students" <photoforum@xxxxxxxxxxxxxxxxxxxxxx> Sent: Sunday, January 16, 2005 6:47 AM Subject: Re: Enlarger filter question Kostas, I assume your talking about the filters to change the contrast in B&W printing. A #2 plus a #1 would give you a #1.5. Think of it this way, a #2 would give you normal contrast and a #1 would give you less contrast. The #1 filter will lesson the contrast that the #2 alone would have given you. A #3 filter is more magenta than a #2. Adding a #1 and a#2 will give you less magenta than the #2 alone. A #4 and a #2 would probably give you the contrast of a #3 filter. A full set of filters should include all the filters from 1 through 5 plus all the half steps between. Walter ======================================================================== ============================ On Saturday, January 15, 2005, at 04:01 AM, kpp@xxxxxxxxxx wrote: > a quick one. > Can enlarger filters be combined? i.e. is no1 + no2 together a no3? > thanks, kostas > > > _______________________________________________________________________ > ______________ > http://www.mailbox.gr ÁðïêôÞóôå äùñåÜí ôï ìïíáäéêü óáò e-mail. > http://www.thesuperweb.gr Website ìå ÁóöáëÝò Controlpanel áðü 6 Euro > êáé äþñï ôï domain óáò! >
