Really a basic question. I have a Crown with the Schneider 135 mm lens with X and M synch in Compur shutter. I have a tilt-a-mite and a modest supply of M5 bulbs. What are the speeds for synching those bulbs with my lens? Can I use all the shutter speeds on the package, with the difference just being guide number and how far off the peak output I am? Thanks.

If your shutter has "M" sync then all shutter speeds can be used. The M denotes medium peak in miliseconds. If you look at the guide numbers on the bulb package however, you will notice a notable decrease as you use the higher shutter speeds. Medium peak bulbs include #5, #5B,#8,M5 etc. Also #25,and 25B. Russ