Orion Optics OMC 140 - any experiences?

[AstroFin]

Recently I've been playing with the idea of having a second, more portable telescope to accompany my Celestron CPC 800. I'd like something lightweight and compact but with as much aperture as possible. This is why I'm very interested in the Orion Optics OMC 140, both the standard (~750€) and the Deluxe (~1100€) models. The scope weighs 3.5kg, so it would be easy to mount it on an alt-az mount such as Vixen Porta.  Most of my observing is done within a city, so the main targets would be lunar/planetary. A Mak-Cass sounds like a good choice for my needs.

 

However, it seems that the scope has had a bit of mixed reception among amateurs, so I'd like to hear some first-hand experiences, especially of the newer Carbon Fiber tube model. Is it good optically and mechanically? How's the cool down time compared to a SCT? Am I better off investing my money in something else? If you have the scope, it would be nice to see a picture of your setup as well! ?

 

Clear skies,

Tomi

[Peter Drew]

I have the standard aluminium tube one, it was donated so I'm not sure what level of optics it contains. Side by side it outperformed a 127 Skywatcher Mak which might be expected and on a par with a good Intes Micro MN56. Cool down time was considerable and I also found the micrometer based focuser awkwardly placed and fiddly to use. Good colour correction and minimal image shift when focusing.  Definitely a lunar and planetary telescope.   ?                    

[Stu]

Hi Tomi,

Welcome to the forum.

I've had several OMC140's, and also an OMC200. The 200 was purchased new, but the 140's were all bought used, infact I bought back one that I sold, must be a glutton for punishment!

I think the new ones are very expensive, but the older aluminium tube ones can be very good value on the second hand market.

As Peter says, they take a long time to cool, so be prepared to have creative ways of countering this, either leaving out in a sealed box for a few hours before observing or even wrapping in thermal insulation to reduce tube currents which is gaining traction as a method. The new CF ones have, I think, cooling vents by the corrector plate which may help.

The long focal length makes them a high power, narrow field of view scope at its best for lunar and planetary observing, although brighter, small DSOs like globs and planetary nebulae also show well.

Dew can be an issue, so a dew shield and dew strap are mandatory if your location has dew issues at all.

I do agree that the focuser location is fiddly and difficult to reach at time.

Finally, collimation has been key to getting the best images for me. I got mine professionally adjusted so I was sure it was correct, but also had an issue with a loose primary and a pinched corrector which needed to be sorted out. The views now, with good seeing and a well cooled scope are excellent. 

I'm glad I have mine, particularly for a relatively low investment, but there are definitely easier, less fussy scopes out there.

[johninderby]

I had the CF tube version with the best grade of optics and did have mixed experiences with it. While opticaly excellent found it was very fussy about seeing. When seeing was good it was a great little performer but in times of ordinary seeing found it gave somewhat disappointing views. 

I eventualy sold it on because of this. 

[Vixen4eva]

I`ve had a couple. Brilliant little scope!!! Fantastic for its aperture on the Moon and planets. Does ok on the brighter DSOs too. Recommended!!

Alan

[AstroFin]

Thank you all for the replies! ? It really seems like a mixed bag. 

I might be inclined to go for the 1/4th wave Standard version, due to the more reasonable price. I understand that this would be somewhere near “Sky-Watcher -level” in terms of optical quality.  At this price point I’d expect  the UK-made OMC to be mechanically superior to Chinese made Skymax etc. but from your comments it seems that this might not be the case after all? 

Alan, was any of your scopes a CF version? If so, what are your thoughts on image stability and cool down? 

John, I am concerned that the CF tube might cause a lot more thermal issues compared to an aluminium tube. This combined with the behaviour you described wouldn’t be a good combination. I have experienced the same issue on much larger catadioptrics, such as C11, though. How long was the cool down time on your scope?

Peter, how do you find the focuser knob placement awkward? Is it too close to the visual back? 

Stu, thanks for the advice on collimation. I’ve never needed to collimate a Mak before. Having read a few articles on the issue I know it requires quite a bit of accuracy to get it right. Where I live, the used market for such scopes is very narrow or even non-existent, so the only choice for me would be buying a new one.

 

 

[johninderby]

I used to leave my CF version for an hour to cool down. I had discussions with others with this scope and found I wasn’t alone in experiencing this “problem” When conditions were right it was a great performer but some nights just didn’t perform.  I just put it down to being a very sensitive scope that didn’t like poor seeing. Had a couple of the Skywatcher Maks and never experienced this. 

[Stu]

1 hour ago, AstroFin said:

Stu, thanks for the advice on collimation. I’ve never needed to collimate a Mak before. Having read a few articles on the issue I know it requires quite a bit of accuracy to get it right. 

The Orion Optics Maks have collimation adjustments on them. The OMC200 has a fixed primary and adjustments on the secondary, whilst the OMC140 is the opposite, a fixed secondary spot on the back of the corrector and an adjustable primary. I can only assume the new CF versions are fundamentally the same.

Strangely, with both my 200 and one of the 140s, the primary mirror had come loose so was not sitting correctly. I finally fixed the 200 myself, but got help with the 140, in part because I could not get either end of the scope off! I'm glad I did, as the issue with the corrector being too tightly held was also identified and addressed. The views are now very good when seeing allows.

I think the problem with these scopes is that with a 2000mm focal length, you are always using highish power, and you have to have seeing, collimation and cooling all in your favour for the views to really come together.

[AstroFin]

On 02/01/2019 at 23:50, Stu said:

Strangely, with both my 200 and one of the 140s, the primary mirror had come loose so was not sitting correctly. I finally fixed the 200 myself, but got help with the 140, in part because I could not get either end of the scope off! I'm glad I did, as the issue with the corrector being too tightly held was also identified and addressed. The views are now very good when seeing allows.

Oh my. The scope is beginning to sound more unconvincing the more I read your experiences. ? A loose primary is definitely not something I want to be dealing with. My C8 had a loose secondary due to poor design of the gasket between the secondary mirror and corrector plate, I had to order a new gasket all the way from Starizona in the U.S. 

Thank you all for your replies! This might be steering me to take a look on some other scopes.

 

 

[Tyson M]

I have always been curious about the OMC's (especially the 140 deluxe), but there is just so much negative press about them that it really seems like an expensive gamble. 

[Space Hopper]

On 02/01/2019 at 21:50, Stu said:

Strangely, with both my 200 and one of the 140s, the primary mirror had come loose so was not sitting correctly.....

A primary mirror coming loose on a £7.5K scope.....?

Hmmmmmm......

[Stu]

7 hours ago, Tubby Bear said:

A primary mirror coming loose on a £7.5K scope.....?

Hmmmmmm......

Well to be fair, the 200 was an older style aluminium version so around £2.5k when I bought it new. The 140 was bought used, again aluminium version and under £300. Still shouldn't happen though, the common theme seemed to be a grub screw coming loose which allowed the locking collar to unscrew over time so that the primary was not held tightly. A little thread lock would have done the trick when it was originally assembled!!

[dweller25]

Haven’t owned a 140 but did have a 200mm carbon fiber tubed OMC which gave excellent views when fully cooled and seeing allowed BUT cool down was a major issue even with the fans running. The scopes corrector would often dew up internally before the primary had cooled !!!

I have a C6 now ?

[Stu]

54 minutes ago, dweller25 said:

Haven’t owned a 140 but did have a 200mm carbon fiber tubed OMC which gave excellent views when fully cooled and seeing allowed BUT cool down was a major issue even with the fans running. The scopes corrector would often dew up internally before the primary had cooled !!!

I have a C6 now ?

I had similar experiences of the 200. 140 seems better in this respect

[murray451]

There's a pre-carbon fibre OMC 140 OTA currently going on eBay for £575. I wonder if this is a fair prices given the 'scopes characteristics?

[Stu]

16 minutes ago, murray451 said:

There's a pre-carbon fibre OMC 140 OTA currently going on eBay for £575. I wonder if this is a fair prices given the 'scopes characteristics?

I’ve bought and sold very good aluminium deluxe optics examples for around £300 before, so this feels high.

[Peter Drew]

I sold mine for £200.     🙂

[Space Hopper]

A scope thats always intrigued me, (Mak-Cass) but something every time has stopped me purchasing one.

Both the OO 140 / 200 as well as Questars and all the old Russian stuff. I think it's their aesthetics : they are things of beauty, to me anyway.

I'm sure those of us who follow the second hand market have seen the 'as new' OMC 200 on ABS which is on sale at roughly half price.

Also the IM 715 on here. I'm puzzled as to why neither have sold, and perhaps it really is down to those 3 factors of Cooldown, Collimation and Seeing, as well as their cost in todays world.

 

[murray451]

Thanks all. Getting the impression that it’s not a bargain! 🙂

[Stu]

4 hours ago, Space Hopper said:

I'm sure those of us who follow the second hand market have seen the 'as new' OMC 200 on ABS which is on sale at roughly half price.

I’ve looked at that OMC200 many times! Too much for me. I think I sold my old Ali one for about £1200, something like that. I think the cooling is much better on the CF ones and if money was no object I would give it a go, but it’s not, so I won’t.

[Space Hopper]

I think you nailed it 4 years ago Stu, when you said 'there are definitely easier, less fussy scopes out there'

Very true, and i'm at an age now, where given our weather and general conditions, I don't need fussiness, long cool downs or collimation headaches.

That doesn't stop me desiring a Questar though !!   (probably to look at rather than look through ! 😀)

[alex_stars]

On 01/04/2023 at 12:45, murray451 said:

There's a pre-carbon fibre OMC 140 OTA currently going on eBay for £575. I wonder if this is a fair prices given the 'scopes characteristics?

Hi,

not sure if it is relevant still, but I own a carbon-fibre OMC 140 (deluxe version). The advantage of the pre-carbon tube would be a better cooling behaviour. The carbon tube is a nightmare to temperate, so I personally do not see any advantage of the carbon OTA.

If, and that is a big IF, the focuser is working flawless and the primary mirror is not tilted (due to cork rings giving in), than I think it is worth considering. A SW 150 Mak costs more new and is a whole category lower with respect to the focusing mechanism. I owned a SW 180 Mak and a 127 Mak and both were not comparable to the OMC 140.

However I would not buy any OMC-140 without trying it on-site and check for the issues mentioned above. If it is all good, I think the price named is ok, not a bargain, but OK.

[Stu]

1 hour ago, alex_stars said:

The carbon tube is a nightmare to temperate, so I personally do not see any advantage of the carbon OTA.

That’s interesting, I thought the CF ones were supposed to be easier to get to ambient as they have cooling vents? The Ali OMC200 I had was always a challenge!

[alex_stars]

11 hours ago, Stu said:

That’s interesting, I thought the CF ones were supposed to be easier to get to ambient as they have cooling vents? The Ali OMC200 I had was always a challenge!

Interesting indeed. My 2017 OMC-140 deluxe carbon tube OTA has no cooling vents. Did/does the OMC 200 have those?

[dweller25]

I don’t think any of the OMC140 versions had cooling vents.

I believe new OMC200’s have cooling vents on the front and fans on the back, all versions of the older style OMC200’s just had fans on the back.