Posts Made By: Philip Canard

JMI has them for around $100. Also try University Optics.

You will need extension tubes to put the EP field stop at the proper 55mm distance. Try a 15mm + 7.5mm T-2 system tube plus a Click-Lock. Some EP's will need more or less. The 2" T-2 EP holder will be needed for 2" EP's.

I've been spoiled by the finder that came on my LOMO 150 MC. To beat it, I would have to buy a small refractor with a good quality star diagonal. The Stellarvue F50 can exceed it a bit with the right EP, but not the one that comes standard with the F50. I use an illuminated double reticle 10mm Plossl EP by Celestron with a Rigel illuminator that is programmable for intensity, on and off time and has a reticle focuser. It's around $250 plus postage for the F50 with Celestron EP. The standard finder scopes do not equal this setup, but they don't cost $250+ either.

My Nighthawk II with single speed Crayford can't support a TEC EP turret at zenith with 5 EP's installed due to the excessive weight. Even with the focusing lock engaged. It also does not support binoviewers well. Don't know if a dual speed focuser would do a better job. My JMI dual speed focuser handles heavy binoviewers just fine. The Nighthawk II single speed Crayford is only suitable for single EP's....and I don't mean a 31mm Nagler or 41mm Pan.

My next refractor will have a large Feathertouch focuser of over 2", or I probably will not get a refractor at all. My Russian Mak with 2" visual back will support anything you want to hang on it, as it focuses internally. Small refractors are very limited in what the focuser will support from my limited experience. I have no problem with terrestrial observing with my NH II as the focuser doesn't have to vertically support weight.

Tightening the single speed Crayford focuser too much in order to prevent slipping can damage the roller bearings. None of the Chinese Crayfords will do the heavy work that a Feathertouch focuser takes in stride, or what a dual speed JMI is capable of handling. A 2" diagonal and hefty 2" EP's may tend to slip in a single speed Chinese Crayford when pointed to the zenith. My minimum focuser from now on will be a dual speed JMI.

Yep, the SV F50 was a big upgrade over the Meade F-POS that came on my Meade SN8.

I use a 12mm Omni Plossl in mine most of the time. 17X mag with a 3mm exit pupil snags those globular clusters a lot easier than that mediocre 23mm crosshair EP. It's also nice for huge widefield objects like the Pleiades. Planets are revealed as planets rather than just as bright stars.

Cheap Celestron 2" E-Lux Kellners work very well at f/15 and the 26mm and 32mm E-Lux EP's are very contrasty for deep sky studies with greater AFOV and more viewing comfort than a 25mm or 32mm 1.25" Plossl. The 34mm Axiom is another winner if you want 70 degree AFOV, but contrast is less due to the 4 extra elements. It has less pincushion distortion than a Panoptic and is every bit as sharp from f/10 or longer focal ratio. This is my main deep sky EP in my 6" Mak. I can also recommend the 2" 34mm or 36mm Siebert Observatory as a deep sky EP.

Get a high quality 2" diagonal that's 1/10 wave or better, and get a good binoviewer. Maks and binoviewers were made for each other. I really like the 12.5mm and 18mm Ultima, and 15mm and 23mm Axiom for 1.25" EP's. I use Siebert Star Splitters for highest mags, and the 8.9mm and 9.9mm work especially well in an f/15 Mak as they are 3-element designs with very high contrast. 7.9mmm SS and shorter have a doublet Barlow at the front and slightly lower contrast.

Edmund RKE's are noted as good planetary EP's at cheap prices in Mak scopes. 3-element EP's work very well in Mak scopes, and I am developing a fondness for them due to the high contrast.

The thing about an f/15 scope is that the simple and cheap classic EP's work to perfection in them. f/15 Maks have less central obstruction than f/10 SCT's and therefore higher contrast. The longer focal ratio allows using longer FL EP's with greater eye relief.

The TEC EP turret is a recommended accessory for your Mak. If you do a lot of high mag work, it allows you to quickly select the best mag for the job at hand. Remember, you're getting an excellent star diagonal in the deal. A typical lineup is 30mm Ultima or 23m Axiom, 18mm Ultima, 15mm Axiom, 12.5mm Ultima, 10mm or 7.5mm Ultima. That gives me 5 nearly parfocal EP's to spin in the turret.

If you like to look at planets, you got the right type scope for the job. For lunar studies and equal magnitude doubles, your 7" Mak equals an 8" APO in resolution. I have a 6" Russian Mak, and the more I use it the better I like it. A little dim for deep sky, but tack sharp and contrasty on the brighter stuff.

Meade UWA and TV Naglers are not really what long focal ratio Mak scopes are all about. It's about sharpness and contrast. Maks took the place of long focal ratio achromats.

It's the sorbothane that provides the vibration suppression. Put a thick sheet of sorbothane petween two hockey pucks and you will have a vibration suppression pad, or between two steel discs, or between two wood or hard plastic discs. The commercial version is between two nested plastic discs.

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.

I used the rotating Borg helical to upgrade my LOMO Astele 102MN for planetary viewing. I used the 1.25" Borg nosepiece and dropped the focuser into the 102MN R&P focuser. To offset the 1.5" helical focuser optical path length, I use a Siebert SCT 4 or 1.8X MaxLite binoviewer OCA screwed into the end of the helical nosepiece and it makes it about parfocal with an eyepiece used alone. I prefer this setup to a 2.5X TV Powermate because it adds fine focusing for planetary viewing and costs about the same and is shorter. The 1.8X MaxLite has threads for filters but the Powermate does not. The 1.8X MaxLite is a telecentric magnifier like the Powermate, but much smaller and lighter. You can screw it into a 1.25" extension tube and use it just like a Powermate, plus it screws onto the nosepiece of binoviewers and is fully inserted into a Dob focuser. A bit more versatile than the Powermate. I can also use it on the nonrotating 1.25" Borg helical focuser which can be screwed into a T-threaded Baader diagonal or MaxBright binoviewer or other female T-threaded accessory.

The Baader Hyperion EP's have considerable upgrades for only $10 more than the Stratus. Go to the Alpine Astronomical website and check them out. I suspect that Orion isn't wanting to get caught with unsold inventory so they are quietly getting rid of stock at current prices before they meet the Baader upgrades or replace the Stratus with another EP style. I can see no reason to buy the Stratus when only $10 extra gets you a more versatile EP with nicer coatings in the Hyperion series.