Discovery 13.1 DHQ soda-lime


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Subject: I have these optics
By: Anonymous (xxx.xxx.153.208)
Date: 04/28/2003 12:01:08 pm PDT
In a Truss scope I built for my significant other, and all I can say, is I get some of the prettiest star test rings anybody ever did see....


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Subject: Re: vote by xxx.xxx.249.39
By: Anonymous (xxx.xxx.199.20)
In Reply to: Anonymous (xxx.xxx.249.39) (Original Vote)
Date: 10/14/2003 08:20:27 am PDT
>This scope is big - the advertisements say 43 lbs. for the OTA, the Discovery sonotube 12.5" OTA is 61 lbs., this 13.1" has to be at least that. I bought a hand truck to move it around. I've looked at the Whirlpool Galaxy and M4 so far, could begin to resolve stars in M4 and see bridging between the galaxies in the Whirlpool, this on a night in summer when it hadn't really gotten dark yet, but I couldn't wait as I had to work the next day. I've been trying to use it on Mars, but the short (f/4.5) focal length doesn't lend itself well to planetary viewing - the collimation has to be so precise (Mars is better in my 8" f/6 Dob, so I've been doing 90% of my Mars viewing with it).
>My 2x Orion Shorty Plus Barlow doesn't work with this scope, nor my 7mm Siebert Standard. The 17mm Siebert Ultra does fine as do my 4mm Radian and my various Plossls. The secondary has thumb screws for adjustment.
>The mount is birch, very nice. But, my 8" dob has a wider round base and its legs are much shorter, so it's more stable on the grass.
>The longer tube of this Dob causes so unconfortable viewing positions - too high to sit in a regular chair, low enough to be a real pain in the back, definitely need an observing chair. The scope is a bit harder to position than the 8" dob owing to it's weight.
>In conclusion, for the price this 13.1" Discovery Dob is the light bucket I always wanted for DSOs. The short focal length makes it not so good for planetary viewing (at least until my collimating skills improve), a big drawback if you don't have another scope like I do. But with a little learning and maybe a couple of improvements, I'll have years (decades) of enjoyment with this scope.

Update 10/14/03...I moved the primary mirror up 9/16 inch and now all my eyepieces focus. The focuser is great now that I tightened the allen screw in one of the adjustment knobs. The collimation still needs some tweaking (even with a laser) as Mars just isn't as sharp as the 8" dob, but Saturn nearly overhead was extremely sharp, hmmm.... I found Uranus with this scope and have looked at many of the usual suspects: M80, M31, M32, M110, M15, and the Ring Nebula which had a bit of a brownish color to it compared to the grey I've seen with my other scopes. I had a tremendous view of the Orion Nebula the other night using a older type 21mm Siebert, nebulosity visible throught the field of view, the Trapezium's four stars were visible on-axis but distorted when moved toward the edge of the field of view (caused by mirror or eyepiece I don't know), but the amount of light let through was spectacular!
I'm putting together a Denver observing chair.
A great scope for the money!


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