I have an SB27 that I use with a 601 (6006) and FM10. As such I need to switch back and forth between TTL auto and A auto. The option to do this is set by a switch in the battery compartment. With the switch suitably set you can toggle between A and TTL when powering up by holding one of the buttons down. A or TTL flashes to show it is operating in this switchable mode. The question I have is that the toggle sequence is A *flashing*, A *solid* and TTL *flashing*. I have no idea what the A solid mode is here. Can anyone help ? Also on the SB27 there is button to switch aperture on the flash unit to match that of the lens. Is this for use as a range guide only or does it affect exposure. I assume it is the former. Paul
