Telescope Reviews: Wow, an alt-az mount I really like!

Attached is a picture of a new DM4 mount, I recently purchased in an attempt to find a alt-az mount for "grab and go". To make it usable for my needs, I put together the setup with two adapters that I machined – one for the tripod and one for the dovetail clamp. As you can see in the picture, I am using an AP DOVE08 dovetail clamp, which works well with the narrow Zeiss dovetails I have on all three of my refractors. The refractor pictured is a custom OTA that I recently finished around a Zeiss ED80/840 apo lens. The tripod is a Davis and Sanford Astro600 (Tiffen ST600). It is the tripod AP offers as an alternative for their AP400 mount. I really like this tripod, it is light weight and very rigid – weighing only 6.5 lbs, but with a capacity rated at 50 lbs. It comes with a three-hole pattern for Celestron wedges and I machined a disc to bolt to the tripod and to the DM4. I then machined a disc that bolted to the vertical disc of the DM4, with four tapped holes for the DOVE08 bolt pattern. I also added a couple of fiber discs of high grade gasket material to protect the DM4.

After I finished, I played with it during the daytime, following the included directions for balancing. I was raised in the hobby on an equatorial mount and have used them for 30 years. However, in the past few years I have tried several of the alt-az mounts and have always been disappointed with the balance issue. Not so with this mount. The DM4 balanced very well with my Zeiss ED80 and I couldn’t get over how I could switch eyepieces and the mount stayed on target! The movement was very smooth and stiction wasn’t an issue. I couldn’t wait to try it under nighttime skies! I got my chance last night - a clear night in November in Michigan and following a new purchase – amazing. The NELM was around 6.2 and the seeing was pretty steady (somebody pinch me :^). I spent a couple of hours out under the stars including some cruising through old favorites or just panning through the Milky Way. Once again the movement was very smooth and it was easy to keep targets centered. I gave the setup a “rap” test and the “settle down” time was less than two seconds – excellent for a grab & go! The majority of my time was spent on comet Holmes – an obvious naked eye object. A few times I tried moving the scope away and then panning back to the comet without using the finder scope. The smooth movement made locating the object in this way, easy.

I then decided to give the balance issue a real test, by taking a snapshot of the comet. To do this I used a Stiletto focuser from Stellar Tech and then a Canon 20D DSLR. Both are pretty heavy and have to be switched between focusing and imaging. The DM4 did amazingly well, although not perfectly; I did have to help it a bit. However, I believe that after I gain some experience with the mount, I may find that it handles this difficult task too.

I am pretty fussy when it comes to my equipment and it usually takes me a while before I am convinced that I have a “keeper”. However, I won’t have to with the DM4 – what a excellent product! Think of it, an alt-az that I like - this is a big step for an “equatorial” man like me, but what a great mount!