MN or OA? Pro's and Con's?

I am thinking of one or the other as a next purchase. The DGM OA 4" or the Intes MN56. Any and all of your thoughts , experience's and opinions would be greatly appreciated. Thank you for your time. Allen

Hi Al,

I have never seen an OA scope in person so I can't help with that part but I did own an MN56. The MN56 had VERY GOOD optics but I found it to be frustrating to use. It seemed to never want to reach equilibrium, the stock focuser and finder were terrible, and the scope was a challenge for me to collimate. I would suggest thinking about a 6" reflector and a cooling fan modification. I install cooling fans on my reflectors to scrub the primary, ala Alan Dyer's method and I'm always amazed at the views these Newts put up and how well they keep up with the temperature drops.

Hope this Helped,

Steve

Hi Al,

I spent some time comparing an D&G 5" f12 (it's not the same scope of course) with my MN 56, which may be of some help to you. I did not have Steve's problems with thermal equilibrium (given a good 1/2 hour of cool down time), but his other points are well taken. I now have, but have not installed a feathertouch. The tube is also not round, which is frustrating on a GEM.

Now, we compared the D&G 5", the MN 56, and a Tak 130 f6 reflector, on a good night. The views on Saturn were about the best I have ever had. As best I can remember, resolving power and contrast were impressive in both scopes (THe tak lagged considerably on contrast until we improved a "dew" shield, at which point they were all very close). The MN 56 was not as bright as the other two scopes, just more surfaces. It certainly had the flat field and wide field of view. My general conclusion was that well executed examples of the three types of scopes produced very good results.

The D&G was just huge by comparison. The MN or the Tak work adequately on a Vixen GP (or SP) for visual. The D&G needed a lot more.

Al Ellefson said:

I am thinking of one or the other as a next purchase. The DGM OA 4" or the Intes MN56. Any and all of your thoughts , experience's and opinions would be greatly appreciated. Thank you for your time. Allen

I have the DGM 5.5" scope. It produces very bright images for the aperture, very contrasty. Drawbacks are the long tube requires careful balancing for different eyepieces. For planetary viewing, I've found I need to run a cooling fan most of the night, since the primary is quite thick for its size. This is because it is a segment of a much larger mirror (14"?). Also collimation is very different from a standard newtonian and requires some getting used to. Standard collimation tools are useless with this scope. I would not recommend it as a "quick look" scope for the above reasons.

If you get the MN, consider getting a set of parallax rotating rings and upgrade the focuser. I have both an MN55 and MN86 with this set up on on a GEM. I love them. The 55 is my grab & go while the 86 isn't

Can't say much about your other choice as I have no experience with them. Also, I don't do any imaging. Only visual work.