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Subject: Re: vote by xxx.xxx.206.107
By: Anonymous (xxx.xxx.147.134)
In Reply to: Anonymous (xxx.xxx.206.107) (Original Vote)
Date: 11/16/2004 10:53:26 pm PDT
This scope continues to impress me. I originally stated that there was a noticable loss in contrasts on the planets when compared with say an 80mm apo refractor due to the large central obstruction. However steadier skies has improved the contrasts on the big planets. But where this scope is impressing me is on the fainter objects where its blacker background allows it to outperform longer focal length scopes such as the xt4.5.
>I purchased the 102mn for $248 including shipping. My rating of the scope takes in consideration that it is half the price of its nearest competitor. The things I liked about the scope: 1. (PORTABILITY/TRANSPORTABILITY)built in finderscope won't be damaged when transporting scope
>2.(OPTICAL QUALITY/COATINGS) Once cooled scope star tested very well, edge to edge pinpoint stars
>3.(BIULD QUALITY) Solid tube, metal focuser and camera adapter,
>The things I didn't like:
>1. cool down times of one hour or more are a little long for a portable quick look scope
>2. the large obstruction introduced by the built in finderscope does reduce low contrasts detail on Mars and Jupiter for example. Not bad though, grs and shadow transits still visible
>The scope handles high powers very well. Absolutely no sign of breakdown when looking at Jupiter and Saturn at high power. Sky appears very black and stars are pinpoint giving evidents of a very well directed cone of light coming off the primary. However the central obstruction of 1.5" does reduce contrasts slightly.
Subject: Re: vote by KeithMolkner
By: Anonymous (xxx.xxx.131.188)
In Reply to: KeithMolkner (Original Vote)
Date: 02/01/2009 09:26:49 pm PDT
>The optics on this scope are quite good, with stars coming to nice sharp points. The crispness of stellar images are better in the Lomo than an SCT in that regard. Build quality is generally solid but unrefined in a typical Russian way, although for some reason Lomo uses plastic caps at both ends of the scope (behind the primary and over the corrector) rather than metal, which is disappointing. You can remove the rear cap to speed the cooling of the primary, although I've not yet to determine how much this really does speed the process.
>I have found that you can maintain a perfectly round Airy disc from edge to edge if you are using an eyepiece that supports the f/5.5 aperture. If you are seeing any blurry images with this scope, then suspect your euepiece is at fault!
>The major drawback to this scope is that the secondary obstruction is significantly oversized in order to accomodate the finder assembly. This causes a noticeable reduction in contrast relative to my conventional newtonian which has a proportionally smaller secondary. Contrast on the Lomo is similar to that on my C-5 more or less. Many other Mak-Newts on the market have proportionately smaller secondary obstructions and are often said to have apo-like views. The MN-102 gives a sharp image, but the contrast loss is noticeable and a bit disappointing.
>The contrast loss is most evident at lower magnifications. At 160X or higher on lunar viewing, it is as sharp and contrasty as a refractor.
>The motions on the assembly that rotate between finder and main optics are smooth, and the views through the finder are surprisingly good. There are times I've had to check to see if I'm looking through the finder or the main instrument. On the other hand, because the finder eyepiece is at a right angle to the scope, I have found it helps to affix a red-eye finder to the scope for rough sighting.
>The viewfinder magnification will always be about 1/3 of the main optical tube with any given focal length eyepiece. That preserves a brightness level equivalent to the main optical tube. At very high powers, the finder scope and main OTA may not align too well.
>The focuser is a basic rack and pinion and works fine.
>It can be improved at high powers with a helical focuser. By screwing the front element of a Barlow into a Borg helical focuser, almost any 1.25" eyepiece should be able to focus.
>The most interesting thing about this scope was pointed out to me by Gary Hand of Hands On Optics. This scope can be used without a mount. From a seated position, cradling the scope in your lap, the eyepiece is at the perfect height for viewing. With a low power eyepiece, you can scan the heavens in finderscope mode, then once an interesting object is located, you just click the rotating assembly over to the main optics and you have a nice view through 4" aperture optics. Because of the weight and shape of the tube and the position of the eyepiece, it's possible to hold it steady enough for good viewing at reasonable powers like 25X with no mount.
>This scope excels at lunar and planetary viewing at 100X and up. It deserves to be put on a very good equatorial mount.
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