You can do this but, you will lose 50 % of your texas red signal, as the major portion of this signal is between 610 and 625. You would be better off with a 610 or no more than 615 long pass. ---------- From: owner-confocal To: Multiple recipients of list CONFOCAL Subject: 625nm long pass for Biorad 600 A2 to reduce bleed Date: Thursday, August 10, 1995 11:26AM Has anyone replaced the 600nm long pass filter in the A2 block with a longer wavelength cutoff? This would reduce the bleed of the red end of the FITC emission through the red filter. It seems as if a 625nm cutoff would be appropriate and would not sacrtifice too much of the red emission fro texas red etc. Has anyone tried this? How were the results? From whom was the filter purchased? Omega Optical can supply one on special order and said it should be polished and AR coated for imaging applications. Has anyone purchased a suitable part from another company? Thanks. Milton Charlton University of Toronto