From: "Tom Krajci" From: Mike Simonsen >> determination is so popular is because it can be done unfiltered? >> Isn't there more science that can be done by placing UBVRI filters on >> CCDs while investigating CVs? >...cycling filters is problematic >in CVs because you have to disentangle colour information >from changes due to the ubiquitous flickering. Ideally one >needs several colours simultaneously, but that is likely >beyond most amateur equipment. use some sort of dichroic beamsplitter. You can use one scope, one beamsplitter...but still need to use two detectors. But...dichroic beamsplitters may not be in bandpasses that are commonly accepted as photometric standards. Just some ideas. Tom Krajci Cloudcroft, New Mexico http://overton2.tamu.edu/aset/krajci/ No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 268.2.0/276 - Release Date: 3/7/2006 _______________________________________________