I'm going to re-quote that for emphasis. This is one of those shutters that really acts badly if you cock it and try and reset the speed, and if you cock it at a lower speed and force it up to 500 I read that you can potentially break it.
Originally Posted by edp
I also have one of these. It has no T setting for ground glass focusing but right next to the speed indicator arrow is a little button you can pivot down. Set up your speed and cock the shutter, push this down and the activate the shutter... it stays open for focusing! Cock again and it releases. You don't have to reset your speed to B and use a locking cable for focusing all the time with this feature.