I have the 742 and 685 - the 685 is a LOT brighter and has about the same attenuation of seeing issues. I don't know that I'd make a special point of buying the 685 if you like the 742 but if you have neither, I'd buy the 685.
Beautiful images, Brian.
Jupiter in very good seeing: 10-17-2012
26 replies to this topic
Posted 21 October 2012 - 05:44 PM
Thanks Paul! I agree that the main benefit seems to be the brighter image which is no small thing if you are not shooting with a C14. For instance, folks using C8/C925 class OTAs in particular might want to consider the 685nm filter...