Orion Optics OMC200 Maksutov

[dweller25]

Thanks to a fellow SGL forum member I am now lucky enough to own this superb planetary scope.

It's a 200mm F/20 Carbon Fiber Rumak so that's a whopping 4mts focal length,  a 20mm Televue Plossl gives x200 !!!

The Orion Optics test printout shows the mirrors are 1/8th wave and have a Strehl of 0.987.

The scope was in really excellent condition when I picked it up and all I have done is to put tube rings on so I could attach a carry handle.

The Vixen GP-DX handles the 9kg scope with ease up to around the x300 mark.

COOL DOWN - If you keep this type of scope in a centrally heated house you will have problems cooling it. Mine is kept in a cool location all the time and then put out with the 2 internal in/out fans running - it's ready to go in around one hour. After this I turn the fans on and off occasionally just to help equalize the internals of the scope with the external temperatures. Keeping the fans on all the time creates unwelcome tube currents.

COLLIMATION - Three small hex head screws on the secondary are all that's needed to adjust collimation. The scope arrived in perfect collimation and despite numerous trips in and out of the house over the last month collimation is still spot on.

MIRROR FLIP - None.

FOCUS SHIFT - Focus is adjusted using a micrometer and is just superb, no shift and the ability to fine tune the focus point - essential for the planets.

THE VIEWS - stars are tight pinpoints with a fine airy disk around them, planetary detail is good but I find contrast to be a little low, here is a recent drawing of Jupiter.......

On the planets this scope outperforms my Takahashi FS128 by some margin , in fact I think it would match a 6" APO and overall I am delighted with it.

I think the contrast issue is due to having 200mm of light gathering which gives me a 1mm exit pupil at x200 which may wash away some of the lower contrast planetary features - I plan to experiment with Neutral density filters.

[knobby]

Looks nice as well as nice looks :-) if you follow my trail of thought

[Mike73]

Looks very nice indeed David.

I didnt realise that you were using this scope when we compared Jupiter sketches, I think I commented at the time that you picked out more detail and now I understand why! 

I take it you have tried coloured filters in the past? Would they not be a better option than ND filters?

[dweller25]

Thanks Knobby.

Mike - I have tried coloured filters and personally found they brought very little to the party in terms of detail but gave a strong/false colour to the views, I prefer the natural look.

I am going to try a Neodymium filter tonight......

[John]

Good report David and it looks a very nice scope too   

...Mike - I have tried coloured filters and personally found they brought very little to the party in terms of detail but gave a strong/false colour to the views, I prefer the natural look.....

Thats just how I've found filters for planetary use as well !. I'll be interested in your views on the Neodymium though, all the same.

My general inclination, through all types of viewing, is not to use filters as far as possible. 

[nightfisher]

David, i spotted your wanted add and wondered if you would get one, when i saw this post i wondered if you had got bigmaksutov`s one but yours is clearly a different scope!

Nice instrument, i look forward to further reports, a 25mm ortho would give some superb views...........congrats

[dweller25]

@John - Tried the Neodymium filter - on the plus side it does reduce the light throughput and it does increase contrast - on the negative side it gives a pronounced blue cast to the views -  I would say the pros just outweigh the cons.

@Jules - Thanks and I will let you know if I move to Orthos....

[Caldwell14]

@John - Tried the Neodymium filter - on the plus side it does reduce the light throughput and it does increase contrast - on the negative side it gives a pronounced blue cast to the views .

I concur. Actually I found that cheap 10 quid moon/skyglow rioters you can buy on Ebay work every bit as well.

[andrew s]

Glad to see you enjoying it. Have you had a go at the sun yet? Very impressed with your drawing skills.

Regards Andrew

[NickK]

I was looking at one of these as a long fl scope.. then all of a sudden they stopped making them (only the 140 is being sold now). Very annoying.. They seem like a great planet scope

[dweller25]

@Andrew - yes I tried it on the Sun at the same time as I took the photos above and saw some very sharp and detailed Sun spots - first time ever and I was very pleased. I had the scope out last night to look at Jupiter and despite it being 3 months past opposition the OMC still showed excellent detail - Mars was a different story though - it's too low at the moment.....

@NickK - I would say they are a dedicated planetary scope - the 4mtr focal length makes it hard to get under x125. OO are making them again now - they are listed on the website.

[Live_Steam_Mad]

Have you ever compared your OMC200 to a decent C11 SCT ? I am interested to know if there is more detail to be seen on Jupiter, Mars, and Saturn if I buy an OMC 200 ? I already have an excellent sample 7" Meade Mak with at least 1/6 wave optics, and my although there is more scattered light in my C11, the actual amount of detail visible in my C11 (non-Edge) was about 1/3 more at 350x, on a night of very good seeing, on Jupiter. My C11 also outperformed my 7" Mak on Epsilon Lyrae. I would like to know if the OMC200 outperforms my C11 ?

Regards,

Alistair G.

[dweller25]

Hi Alistair, Never had a C11 so sorry cannot comment on the relative perormances.

[Alkaid]

Hi David,

Thanks, good read. In your original post you mention a relationship between contrast and exit pupil, something about 1mm exit pupil washing contrast away. Is there an optimum exit pupil for planetary? Can it be calculated at all?

Thanks

[alan potts]

Congratulations on the new scope, I have to say I am a little green as I would have liked it myself and If I had been in England at the time it would have been buy and then worry about how to get it home.

Only the other day I read a report that said nothing can match a Takahashi refractor and I think the 128 was mentioned, I've also read a report by a member that says this scope is the bee's knees, it is only an opinion after all but I personally would love to work a review on both over a few weeks.

Great scope I hope it didn't come with poor weather as an extra.

Alan

[dweller25]

@Steve - I think the optimal exit pupil for the planets is around the 0.7/0.8 mm mark, so for the OMC200 I would be up at x250 which most nights my local seeing will not allow !

Using a 20mm Plossl I found that using a 20% reduction ND filter worked a treat.

@Alan - I have an FS128 - the OMC200 gives visibly better performance but takes longer to cool than the Tak.

[Dave In Vermont]

Wow! That's one fascinating piece of glass! F20 must be wild for planetary observing. Regards filters, I'd give a simple Blue #80A and, perhaps, a Yellow #8 a try (not both at once) and see where that goes visually. My only reservations about my getting a clone of that amazing instrument is that it would be murder for using my video-cams with. I wonder what focal-reducers would do in that...

Nice scope!

Clear Skies!

Dave

[nicks90]

Have you ever tried Jupiter with a UHC filter? Sounds weird, but I was blown away by the extra detail I could see through my 12" dob compared to my neo filter.

It was very green, but once you got passed that it was excellent.

[faulksy]

uhc is great on jupiter , you can realy pile on the power then, over 400x is often great

[dweller25]

Never tried a UHC on Jupiter but I have one so will give it a go .......