Making a guide slide - guiding the old fashioned way

[timwetherell]

Starting to enjoy a bit of astrophotography with my Sony A7s but need to correct the drive during long exposures. Autoguider is of course the easiest solution, but I kinda like doing things the old fashioned way. I'm probably the last man alive still using setting circles!  Anyway, trouble with manual guiding is that the thing you're photographing is almost never in exactly the same place as a decent guide star. Been thinking of all the ways to move the guide scope off axis, like classical three screw finder mount etc. Trouble is it's an 80mm guide scope so quite big and heavy and screws are very fiddly to use all the time. So decided it's probably easiest to move eyepiece instead. 

This is my home made rotate and slide stage that allows the eyepiece to be slid and locked anywhere over a 50mm image circle from the objective which amounts to about 5° of sky.  I've incorporated a 2x barlow into the guide eyepiece so it has an effective focal length of about 6mm equating to 100x. Of course a CCD doesn't need that but eyeballs kinda do to get a decent level of precision.

Still working on cosmetic improvements to the guidescope but the system seems to work well. now I need a clever solution to the problem of me leaving the guide illuminator on every time and wasting batteries. Current solution being to buy then in a 50 pack but that's not sustainable!