WARNING: Posting from a Commercial Domain! Despite protestations to the contrary it is quite possible to efficiently image Texas Red with a 625nm long pass filter. I used a 630 [Hanzel et al EMBO J., 1991, 10:10:9:2363-2373] to achieve <2% crosstalk of the Texas Red signal in the Fluorescein Channel (540DF40) and this was with an Argon Ion Laser (488/514). Our users routinely image Texas Red and Propidium Iodide with barrier filters of 600 to 625EFLP depending on the strength of the red signal and requirements for spectra separation. david hanzel Molecular Dynamics [log in to unmask] http://www.mdyn.com ______________________________ Reply Separator _________________________________ Subject: 625nm long pass for Biorad 600 A2 to reduce bleed Author: Confocal Microscopy List <[log in to unmask]> at Interlink Date: 8/10/95 8:33 AM 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