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mak-newt

Started by kevin7m, 11/29/2006 07:29AM
Posted 11/29/2006 07:29AM Opening Post
I was hoping to get some feed back on these 2 scopes. The Lomo Astele 203MN and the Intes Micro MN76. I have read some stuff already about the Intes-Micro scopes and for the most part have found that they are good quality scopes (except for maybe the focuser :S ) but I can't seem to find much about Lomo Astele scope. I like the idea that it has the finder scope built in but that is also what makes me a little apprehensive. They are both about the same cost so I was hoping to get some feed back on overall design and quality of these two scopes.

Thanx in advance smile
Kev
Posted 11/29/2006 10:05AM #1
Watch your secondary obstruction size. Bigger = less contrast.

Rolando
Posted 11/30/2006 06:38AM #2
Hi Kevin,

Don't know about the Astele, but I have owned a couple of MNs including an MN76. The MN76 was probably the best combination of performance and value I have ever found. Collimation was easy and rarely needed, optics razor sharp given good seeing and cool down seldom an issue here in California. Downside - weight, the crappy focuser you mentioned, a crappy finder and occasional dewing. I often wish I hadn't sold the MN76!
Posted 12/01/2006 09:20PM | Edited 12/01/2006 09:47PM #3
It may be impossible for you to locate an Astele 203MN. They are somewhere between rare and unobtainable. I can only report on the little LOMO Astele 102MN that I have. Built very well. Holds collimation. Very good star test. Focuser could be smoother and lacks a locking mechanism for holding heavy binoviewer. Drilling and tapping a hole and a nylon thumbscrew solves that problem. I use a Borg 1.25" helical focuser for single EP's which totally gets rid of the fine focusing issue at high power. A Siebert 2X 1.25" telecentric OCA called the "SCT 4" is screwed into the Borg focuser nosepiece adapter and takes up the optical path length of the Borg unit and allows focus to be reached, and it is almost parfocal without the OCA in place. Turns the OTA into an f/10 unit, which is more practical for general visual use. The Borg helical focuser is the cheapest high-quality upgrade path for the LOMO focuser problem, and would probably work on the Intes units just as well.

My LOMO 102MN came with very good scope rings and a sliding holder that is easily mounted to a Vixen dovetail bar, or you could have the wider LOMO dovetail milled down to Vixen dimensions if you could stand to lose the sliding holder. The holder and dovetail are safety grooved to prevent dropping to ground.

Dew-Not custom made me a corrector heater strap to my specs for $22.00 plus shipping. The rear cap fit loosely, which I fixed with strips of tape. Includes plastic domed front cap. Unit is backpackable to remote sites and can use the Stellarvue M1 alt-az mount on grab-n-go tripod, which I use for quick views. Fast f/5.5 speed of Mak-Newt allows moderate f/10 focal ratio after 1.8X Siebert OCA is implemented for binoviewing. This allows good deep sky performance with 15mm to 30mm EP's.

The removeable LOMO focuser with steel port cap allows easy transport and the focuser is rotateable to best position. The focuser is extremely rigid and holds my binoviewer with no flexing. The finder changes power when EP is changed, and will be about 30% of the main mirror mag. This means finder brightness also changes with magnification change. Optical quality exceeds that of generic Chinese 30mm finders. The back cover pops off for rapid main mirror cooldown and exposes the entire back of the mirror. Cooldown is thus extremely fast, as good as a 4" refractor.

If used at high power on extended objects, which is mostly lunar viewing in my case, the obstructed optics actually see an increase in image contrast in the top third of useful range, relative to a refractor. Rutten and van Venrooji noted this in their book, Telescope Optics. That's the 200X to 300X range in my scope, right where I use it for lunar viewing. At low and mid powers, contrast suffers relative to a refractor. Optics are diffraction limited, and easily passes 1/4 wavefront star test criteria. LOMO claimed 1/6 wave performance for the 102MN Mak-Newt. Mak-Cass performance is 1/8 wave for 135mm and larger apertures. There is no internal baffling, which reduces tube diameter a bit. LOMO uses a very coarse flat black paint that sucks light, and baffling is of no use on planetary scopes anyway when viewing bright objects as the baffles never intercept the direct light beam. Good call by LOMO. As far as off axis light, I am rarely bothered by it. That flat black paint is some of the best.

The LOMO dovetail bar and sliding holder fits no mount system that I know of except the LOMO EQ mounts. The 203MN was never imported to this country, as far as I know. If I wanted a LOMO Astele scope, I would commission Rex McDaniel at AstroStuff to find me one at the star parties he frequents from one of his old customers. He was one of the biggest LOMO dealers, and also contact Gary Hand at Hands on Optics. I bought a LOMO Astele scope from each of them, and both scopes are killer, the best scopes I own. I have no intentions of selling either scope for what I paid, as I feel they are very undervalued right now. The overall build quality, except for the coarse (but strong) focusing mechanism, is to a very high and extremely rugged standard. The outer tube is a machined unit rather than rolled and welded. Inspectors and workers sign their name in the included booklet. It looks and performs like a serious instrument intended for schools and advanced amateurs rather than a beginner scope. The price in Russia (converting $600 to rubles) would put it far out of the beginner league (about 4 months pay for the average Russian worker), which is better covered by the smaller TAL Newtonian and achromatic refractor scopes coming out of Novosibirsk. Still, this price is peanuts for the quality, and it's a shame that western buyers bought junky Asian scopes for a couple hundred dollars less rather than these very serious LOMO Astele scopes. As a lunar scope during the first and last quarter phases when the moon is at a low angle and seeing limits mags to around 200X, the little 102MN is unbeaten by my 6" and 8" scopes.

If you can't find an Astele 203MN, don't be afraid to pick up one of the smaller scopes. The Astele 150MC is a very fine Mak-Cass, and was one of the more commonly imported LOMO scopes. It will support 400X to 500X mags with no problem if the seeing permits.
Posted 12/26/2006 10:11PM #4
I use an Orion 6" Mak/Newt and would not trade it for any scope. "Refractor" like images with no secondary color. I often use this scope hand held with a low power eyepiece for stunning views of the sky. High power views are also excellent. Not sure why these scopes are not more popular. Compared to the price of 80mm-100mm "apo" scopes on the market today, a 6" Mak/Newt would make a much better investment in observing dollars!!!!!

Just my 2 cents worth . . . . . .

Kreig