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Kickin' it Old School

astrophotography catadioptric classic equipment Meade optics star party


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Alen Koebel

Kickin' it Old School

This was my first prime-focus astrophoto setup, shown here ready and waiting for a night of imaging at the Starfest star party near Ayton, Ontario, Canada. Based on a Meade MTS-SN6 6-inch f/5 Schmidt-Newtonian telescope, a model introduced in the late 1980's. I bought this one in used condition in 1995.

I observed with it for about five years before modifying it to bring it up to snuff for astrophotography. Aside from the addition of a declination motor and a counterweight bar, both stock items from Meade at the time designed originally for 8-inch SCTs, the telescope needed some minor modifications to its beefy 2-inch helical focuser, primarily to prevent flexure from the weight of my Olympus OM-1 35mm film camera but also to avoid diffraction artifacts from the protrusion of the focusing tube into the optical path with the camera at focus (I chopped it!).

I also modified the pier legs with a few parts from the hardware store to allow individual height adjustments, which was essential to level the mount as a first step to obtaining polar alignment. Given the solid-steel, 1-inch diameter, RA shaft and the very nature of a fork mount, there is of course no polar-alignment scope. I achieved precise polar alignment using the drift method, which was time consuming but very accurate.

The mount proved to be very stable and the approximate 30 arc-second periodic error in the primitive AC drive was relatively easy to manually guide out while looking through an illuminated-reticle eyepiece in a Lumicon 2-inch Newtonian Easy-Guider (an OAG) with a 3X relay diagnal. (For guiding I had also bought a used RA-only Meade AC drive corrector and added a declination control circuit and a wired hand paddle. Did the trick.) I typically did exposures from 30 minutes to one hour. When I hear complaints today about autoguiders not working correctly, I feel no sympathy. :)

I used this setup for film astrophotography from 2002 through 2004. I still have the telescope, although it's now more of a decoration in the dining room that I take outside only occasionally for casual observing. BTW, the bicycle-seat-style chair was purchased from Ikea and proved to be ideal for the job. I still use the chair when imaging.


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