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Mewlon 210: Can you use focal reducer / corrector for visual? Is this the telescope for DSO?

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#1 Mwestcott

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Posted 16 November 2019 - 05:58 PM

I am thinking of getting a Mewlon 210 . Currently I have a Tak 128 FS - a wonderful scope, that is tack sharp . I use for planets, doubles ,and DSO from my suburban (London) skies. My only issue is that on the rare clear night (and they are rare) I feel a little more more aperture would just let me get a deeper peek at some of the globular clusters that I enjoy looking at.
The Mewlon 210 seems to fit the aperture gap, as by my calculations allows 2.4x more light grasp. Anyone used the 210 primarily for DSO? From prior posts I don't think the Mewlon would improve much over the refactor for planets.
Any alternatives to the Mewlon 210? I already have a SCT 9.25 in another site abroad and I am often frustrated by the "woolyness" of the view, despite percent collimating. Inherent in the  SC and drives me crazy. I am put off the SCT design and attrwct d to the Mewlon.
Also another question: I believe Tak sell a focal reducer / corrector for the Mewlon 210 but I believe it can only be used for imaging purposes?
Previous posts seem to indicate that it won't work for visual purposes? I can. never get my head around this but presume it is something to do with the light train. Is that so?  A pity as the corrector would increase the central field of focused view which is quite limited with an un-corrected Dall - Kirkham design. Might help a bit worse the coma.
Finally, sadly the corrected Mewlon 250 CS would be wonderful optically but it is way off my budget , and too heavy for my mount (IEq45) hence I am limited to the 210.
Thanks
Clear skies


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#2 markb

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Posted 16 November 2019 - 07:11 PM

Eliminating the 9.25 does not appear to be on your agenda, and I look forward to reading the Mewlon opinions!

Going off the request a bit...

But on that 9.25, when you are at that remote site take a look at the alignment marks on the secondary, the secondary ring 'notch' position if a Fastar, and the edge markings on the corrector. You can PM me if you want links to recent can threads with info on how to effectuate aligning both the optical and mechanical (baffle tube reference, normally) axes of that scope.

I am on a plane to visit my GPS11, very soft when I bought it, used. The corrector was rotated randomly, the secondary was installed 120 degrees off into the 'wrong' hole of the holder, and the secondary was also randomly rotated! Don't know why people don't follow the Bob's Knob instrictions. Images were soft, but it could be collimated (not a good clue that there was an issue or 4 issues). Partially restoring the factory alignment made a vast improvement, and on this trip I will complete the factory markings alignment before going farther. It looks to be a very sharp scope when done! If you are not replacing the 9.25 it is worth checking. Sometimes even the factory alignments need to be tweeked.

Short answer, I doubt the Mewlon will disappoint, and good luck with the purchase.

#3 bobhen

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Posted 16 November 2019 - 08:05 PM

HERE is a review of the Mewon 210 that is right on the money.

 

I have a 210 and the stars are sharper and the contrast and sky background are darker than in an SCT. Objects seem to pop more in the Mewlon. For any object that fits in the field, the deep sky views are really wonderful.

 

I use all Delites and other eyepieces that are no more than 68 degrees and the coma is not an issue. The Mewlon is not a low power scope. But for the smaller stuff, it is really fantastic.

 

Use your refractor for the objects that need low power and a wider field.

 

For the planets and moon it does take better than average seeing with objects well placed and a thermally stable Mewlon. But if the conditions are right, it will pull slightly ahead of your 128 on the planets and more so on the moon. I have Tak TSA 120 and they play nice together.

 

The Celestron Edge scopes give you a flatter field and they are of course less expensive.

 

I use a 2" .7 Antares reducer visually with my Mewlon and an image intensifier and that works well. But again, the field is less than 50 degrees and not a wide 82 or 100-degrees, so take that into consideration.

 

Bottom line: Great deep sky scope for anything that fits in the field. 

 

Bob


Edited by bobhen, 16 November 2019 - 08:06 PM.

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#4 dr.who

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Posted 17 November 2019 - 12:32 AM

I own the 210 and the 250. You will really enjoy the 210. Especially with binoviewers. It works super well on small DSO including Glob’s. But I think it will surprise you on the planets too. It does brilliantly on the planets. It will nicely compliment not compete with your 128. If you can swing it, grab the Skywatcher AZ-EQ6. That way you can use both at the same time.

I can’t comment on the reducer. It never crossed my mind to try it. To me the Mewlon is for the small and faint stuff as well as the planets whereas my TSA-120 is for the big and wide stuff.

#5 Mwestcott

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Posted 17 November 2019 - 05:49 PM

Thanks to all for your comments. From what I am hearing tne Mewlon  will perform well for globular clusters and small DSO objects, if the conditions are good. And will compliment my refractor. 

Will take a look st my 9.25 SCT to see if I can improve it and just make the stars tighter. It seems well collimating. 



#6 JOEinCO

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Posted 17 November 2019 - 08:53 PM

.......Will take a look st my 9.25 SCT to see if I can improve it and just make the stars tighter. It seems well collimating. 

Describe your collimation process and exactly what you see. Describe specifically your out-of-focus process, and how far you take it out of focus both inside and outside focus when collimating.



#7 Reid W

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Posted 17 November 2019 - 10:06 PM

I just acquired a 2019 210.  Total observing time so far is about 2 hours over 3 sessions.

 

I sold my 9.25 after bringing in a older deforked C11.  The C11 was improved this year with the installation of Reflectix.  In fact, the Reflectix made the C11 my "roll and go" setup.  It delivers incredible planetary views with the binoviewers.  I was totally content with this setup until the opportunity to acquire the Mewlon from a reliable colleague materialized.

 

Contrast and pin point star wise-the Mewlon operates in another realm from the C11.  The C11 shows more stars in the double cluster asterism but the Mewlon field is seemingly flatter.    

 

The C9.25 seemed to be fussier with cooling and seeing conditions than the 11, even before the 11's Reflectix wrap.  My very early opinion is that the M210 is not as sensitive as the 9.25.  The views at 80x are superb, but late fall/winter do not give too many days of steady seeing.  As such, doubles in the 210 ... I need more time here.  Early views are promising.



#8 OJS

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Posted 18 November 2019 - 07:44 PM

I have an FS-128 and recently acquired a Mewlon 210. The 210 complements the 128 very well; it is considerably more impressive on compact DSO's like open/globular clusters and planetary nebula. Examples: in the 128, M-52 shows a small scattering of stars at one end of the cluster, the rest looks nebulous. In the 210 the cluster is resolved throughout (and is quite beautiful). In the 128 M-76 can be seen as a faint, vaguely rectangular smudge. In the 210 it shows its hourglass shape.

  Stars colors are more saturated/vivid in the 210. Example: The triple Iota Cas. is white, red, blue. Thes e can be seen in the 128 but are less striking.

   But with my local seeing, close doubles at high power are often sharper in the 128. Example: Delta Cyg. can show a steady near-textbook pair of Airy discs, while the Mewlon shows the discs scintillating, harder to resolve, or resolved only at fleeting moments. (I recall looking at the double-double in the 210, and when the image was steady (only a second!) I was surprised at the "greater" separation between each pair;  clearly the Airy discs are smaller in the 210 than the 128 ).

 

 

The Moon is breath-taking in the 210. It is in the 128, but more detail in the Mewlon.

 

 

My backyard has a ClearDarkSky color code of light green. Get the Mewlon out of the city so it can show its stuff.

 

Hope this helps. (rotate a negative 90 deg.!)

 



#9 OJS

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Posted 18 November 2019 - 07:49 PM

I have an FS-128 and recently acquired a Mewlon 210. The 210 complements the 128 very well; it is considerably more impressive on compact DSO's like open/globular clusters and planetary nebula. Examples: in the 128, M-52 shows a small scattering of stars at one end of the cluster, the rest looks nebulous. In the 210 the cluster is resolved throughout (and is quite beautiful). In the 128 M-76 can be seen as a faint, vaguely rectangular smudge. In the 210 it shows its hourglass shape.

  Stars colors are more saturated/vivid in the 210. Example: The triple Iota Cas. is white, red, blue. Thes e can be seen in the 128 but are less striking.

   But with my local seeing, close doubles at high power are often sharper in the 128. Example: Delta Cyg. can show a steady near-textbook pair of Airy discs, while the Mewlon shows the discs scintillating, harder to resolve, or resolved only at fleeting moments. (I recall looking at the double-double in the 210, and when the image was steady (only a second!) I was surprised at the "greater" separation between each pair;  clearly the Airy discs are smaller in the 210 than the 128 ).

 

 

The Moon is breath-taking in the 210. It is in the 128, but more detail in the Mewlon.

 

 

My backyard has a ClearDarkSky color code of light green. Get the Mewlon out of the city so it can show its stuff.

 

Hope this helps.

 

(rotate a negative 90 deg.!)

 

IMG_0230(1).jpg


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#10 bobhen

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Posted 19 November 2019 - 07:30 AM

I have an FS-128 and recently acquired a Mewlon 210. The 210 complements the 128 very well; it is considerably more impressive on compact DSO's like open/globular clusters and planetary nebula. Examples: in the 128, M-52 shows a small scattering of stars at one end of the cluster, the rest looks nebulous. In the 210 the cluster is resolved throughout (and is quite beautiful). In the 128 M-76 can be seen as a faint, vaguely rectangular smudge. In the 210 it shows its hourglass shape.

  Stars colors are more saturated/vivid in the 210. Example: The triple Iota Cas. is white, red, blue. Thes e can be seen in the 128 but are less striking.

   But with my local seeing, close doubles at high power are often sharper in the 128. Example: Delta Cyg. can show a steady near-textbook pair of Airy discs, while the Mewlon shows the discs scintillating, harder to resolve, or resolved only at fleeting moments. (I recall looking at the double-double in the 210, and when the image was steady (only a second!) I was surprised at the "greater" separation between each pair;  clearly the Airy discs are smaller in the 210 than the 128 ).

 

 

The Moon is breath-taking in the 210. It is in the 128, but more detail in the Mewlon.

 

 

My backyard has a ClearDarkSky color code of light green. Get the Mewlon out of the city so it can show its stuff.

 

Hope this helps.

 

(rotate a negative 90 deg.!)

 

attachicon.gif IMG_0228.jpgattachicon.gif IMG_0230(1).jpg

I have a Tak TSA 120 and the Mewlon 210 and the above matches my experience exactly.

 

The Mewlon 210 is one of my all-time favorite lunar scopes! On the planets, and really fine planetary details, the seeing needs to be better than average for the Mewlon to start to pull away from a FS 128 or TSA 120.

 

Bob


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#11 Reid W

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Posted 19 November 2019 - 07:34 AM

Ok.  I have this rig   

 

https://www.denkmeie...tar-diagonal-r1

 

and spent about an hour last evening with a 2" 28mm 68° E.S. on a variety of PNs and OCs.  

 

To answer the original question; yes, you can use a reducer for visual.  Views are 25% ?? wider.  Background is a bit brighter, stars are just as tight, if not, tighter.  

 

I also have the Celestron sct f6.3 reducer/corrector and a special sleve that converts the above to a slip-in 2"accessory.  Over the next few days I'll try that with 1.25" diag/eyepieces.


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