I recently purchased an Orion 10XT dobsonian telescope and was experimenting with locations for my Telrad 1X finder. I originally placed it on the tube of the XT10 along side the Orion 9x50 finder. I tried this for one night and was constantly having to get on my knees and crane my neck over in order to use the Telrad. I realized this wouldn't work long term so I started looking for alternatives. Here are the results.
This is a side view of the Telrad on top of the 9x50 finder. I used wire ties to hold the Telrad to the finder bracket. Note the foam rubber between the Telrad and the finder. This serves several purposes. First it protects the finder from being scratched by the Telrad, it also raises the Telrad up a little bit so it doesn't interfere with the lenses cap on the front of the finder. And more importantly it takes up some of the slack from the expansion and contraction that occurs throught the evening.
This is the front view showing how the Teldad is mounted at an angle. This is done so the Telrad does not intefere with the finder's adjustment screws.
The above system worked reasonably well although it was sometimes a little bit of a streach to see through the Telrad. I used this method up until I converted to a Orion 9x50 RACI (Right angle correct image) Finder. As soon as I swapped the finder the Telrad was too long for the finder and my head tended to bump into the Telrad when I tried to look in the finder eyepiece. So I removed the Telrad and repositioned it between the finder bracket and the XT10 focuser.
I was very careful when placing this so that there was no interference getting to the power switch, with the dust cover, Telrad mounting screws, focuser, and making sure my head didn't bump the Telrdad when looking through an eyepiece. The only part I forgot was adjustment of the Telrad. The adjustment screw on the left is a little difficult to get to.
So far I am very pleased with this Telrad location. It doesn't require a lot of contortions in order to look through the Telrad.
So this seems to be the correct and final answer.
I unbolted the finder bracket and moved it away from the focuser and reattached it with a single bolt. It seems to hold just fine. This now gives enough room for the Telrad to fit between the focuser and finder correctly.
This pictures shows the current mounting of the Telrad. The red rubber band is holding on the Kedrick Telrad dew heater pad to the side of the Telrad.
I had to trim the Telrad base a little bit to get it to fit.
I've have been having a lot of problems with dew when observing from my backyard. So I constructed a simple dew shield using 1/8" foam rubber. Haven't had a problem with dew since.
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