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LOMO Astele 203 MCT

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#1 maknewtnut

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Posted 11 January 2013 - 12:53 AM

Via request, some pics and info on a rare bird. Some of the digging I've done has revealed that possibly as few as 4 of these were made. The badging includes the EL stamp, which indicates a fork mounted model (although I obtained it as an OTA only). That's a bit odd as it also has a short Tak V width dovetail plate attached, which also bears the serial number.

It's much longer than most 8" f/10 cats. Rough measurements and estimates lead me to believe it might have an f/3.3 primary and 3x secondary...which is definitely a departure from most cats of this focal ratio.

The rear cover was originally held on by screws. I added the retained thumbscrews as part of the cooling modifications. The focuser is via micrometer, which is exceptionally smooth. Image shift is practically nonexistent due to the incredibly close tolerance between baffle and slide.

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#2 maknewtnut

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Posted 11 January 2013 - 01:00 AM

I added the rear port cap I had from an I-M MCT, which has the same pebble finish. When I received it, there was also a Dakin 1.5 Barlow glued into the rear port, which has been removed.

The (2)30mm holes were added to the rear cover and cell plate to accomodate (2)30mmx6mm fans I received today. This evening I added the fan mounting holes, routing holes for wiring, and a power jack.

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#3 maknewtnut

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Posted 11 January 2013 - 01:10 AM

A first glance might lead one to believe this Mak is a Gregory due to the reflective surface seen from the front. It is a Rumak. The secondary likely has a matching radius on it's rear, and then precisely glued to the corrector. The secondary baffle is then attached to the secondary.

In the thread this one originated from I made mention of initially changing one of the primary collimation screws to even get the primary baffle to line up with the secondary. After finding and repairing the root cause (a skewed primary baffle tube), collimation was as close to dead on from a neutral setting as I have ever experienced.

Corrector retention is via the front mounting plate. Underneath the plate is a unique arrangement of spring steel plates in a wave pattern. That applies a clamp load just sufficient enough for retention w/o inducing stress, and it's adjustable via setscrews. Very cool engineering.

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#4 maknewtnut

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Posted 11 January 2013 - 01:22 AM

Even the tube itself is noteworthy. It is not rolled, but rather machined. The first time I picked up this instrument a couple of years ago, it prompted the thought that I might retube it. After analysis, even the tube is a work of industrial art.

Earlier I mentioned that a Vixen width (although the taper on it's sides is steeper, like some Taks) dovetail plate is attached. You can see those mounting tabs in this pic. Despite it's bulk (12.7kg), the combination of no flex between tube and dovetail and the smooth focuser made this telescope useable for visual use on a GM8. I never, never expected that. It will however get a heavier mount of it's own.

After the repair to the primary baffle and addition of fan holes to allow for an improvement to passive cooling, the telescope provided views of Jupiter and double stars on nights with temp below freezing that were quite impressive.

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#5 TxStars

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Posted 11 January 2013 - 02:15 AM

Here is some info:
http://www.lomoameri...m/Astele200.htm

#6 Bob Abraham

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Posted 11 January 2013 - 10:25 AM

Mark: thank very much for posting these pictures... it's a very interesting telescope!

Bob

#7 Bob Abraham

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Posted 11 January 2013 - 11:46 AM

Thanks for the link. Do you know if LOMO is still making these Maks? The website looks like it was updated recently but most of the LOMO Maksutovs I've seen have been quite old.

They seem like nice scopes, although the secondary looks pretty big (about 37% from the specs on the website for the 8" model).

Bob

Here is some info:
http://www.lomoameri...m/Astele200.htm



#8 maknewtnut

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Posted 11 January 2013 - 03:32 PM

I don't believe LOMO is producing any consumer optics at this time. CO around 36% is optimum for any f/10 cat, around 31% for f/12's, and around 26% for f/15's..give or take a few points.

#9 Bob Abraham

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Posted 11 January 2013 - 10:32 PM

Makes sense. Thanks again for the pictures Mark.

#10 maknewtnut

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Posted 12 January 2013 - 01:30 AM

One more after finishing installation of the fans, wiring, and jack. Exhaust ports are around the circumference of the rear plate. The empty fork mounting holes act as exhaust ports as well. The power jack is at the bottom of the rear plate below the bottom fan.

The fans are silent for all intents and purposes. No vibration either, although magnification wasn't pushed tonight with the jet stream sitting overhead. It was bitter cold at 15* F. The telescope cooled enough for stable images after about 50 minutes with the fans running after coming from a heated garage, which is around 50* F. It got even better over the second hour.

One attribute stands out after a few sessions now. The sky is an absolute pitch black with very little scatter even around Jupiter.

Even cleaned and installed what turned out to be a very impressive 40mm finderscope with helical focuser and illuminator port (although my Rigel Pulseguide did not fit). I believe I'll have to obtain an illuminator with 10mm x .75 thread pitch.

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#11 Andy Howie

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Posted 13 January 2013 - 10:10 AM

Lovely pics of a fascinating scope. I've never seen one quite so close up!

The tube really caught my eye. My year 2001 8" Klevtsov, also has a machined, thick aluminium tube(2.5-3mm at thinest points). Even has machined grooves the full length of the interior. Good ole Russian tank like build.

The focus knob, looks top quality and I've heard only good things regarding the 40mm Lomo finders.

Quality bit of kit you have there Mark. I hope you report back and add to this thread over the months ahead.

Cheers,
Andy.

#12 DHurst

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Posted 15 January 2013 - 11:09 PM

Hey Mark,
What is the vintage of the scope? Pretty darn cool!

#13 Edwin

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Posted 16 January 2013 - 03:53 AM

Good ole Russian tank like build.


Yeah, Russian optics rule !






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