My application of digital SLRs is chiefly to fit upgrades to medical and\nscientific instruments that were originally fitted with 35mm film\ncameras ([URL]http://www.truetex.com/micad.htm[/URL]). While for many instruments\nshutter lag is not critical, on certain ones the significant difference\nbetween film and digital shutter lag is critical.\n\nI've timed several old film SLRs (by taking 30 fps video and stepping\nthrough frames) and found that they had a typical shutter lag of only 30\nto 50 milliseconds. On a digital SLR like the Canon 400D I measure this\nat 133 msec (although 100 msec reputed at\n[URL]http://www.impulseadventure.com/photo/shutter-lag.html[/URL], I can't find a\nCanon spec on this). With mirror lockup on the 400D you can get this\ndown to about 60 msec, but that still about twice what the old cameras\nneeded without mirror lockup. Some of the higher-end DSLRs improve the\nlag (Nikon sez of the Nikon D2H, "remarkably short 37 millisecond\nshutter time lag is comparable to a fast film SLR").\n\nWhy are DSLRs slower to fire? The mirror and shutter are smaller, so it\nseems they should be faster. Or is this some electronic imaging\nlimitation?\n\nAnything to be done with models like the Canon 400D to speed them up for\ninstrumentation?\n\nThe mirror lockup feature on the Canon 400D seems really clumsy. You\nhave to push the shutter twice to take one photo. Is there some hack or\nsomething to get this camera to lock the mirror up for all photos?