623 replies to this topic

[dr.who]

When I was doing my research on the Takahashi Mewlon family of scopes I wasn't able to find very much out there that was related to what I wanted to find out. These scopes tend to be pretty rare in the wild and thus there isn't all that much out there. The things I was looking for were:

What accessories worked with the scopes
What focusers would be compatible
What rings or mounting plates could be used
How the views were compared to other scopes I had used
What was the size of the scopes
How much did they weigh
How long does it take to cool them
How hard are they to collimate

And so on. Since I am now the owner of a Mewlon 210 and a Mewlon 250 I want to use this thread to document my own findings and experiences with the scopes as well as constructive information and experiences both good and bad ONLY ON THE TAKAHASHI MEWLON SERIES so that hopefully someone like me coming along behind me doesn't have to go through the learning curve I did.

Please note the information in bold underline capitals. That means I do not want this thread to drift off course or to start discussing other scopes unless it is in relation to the Mewlon series. For example I have done side by side comparisons between an 8" and 11" SCT and the Mewlon 210 so I will likely be mentioning what I found in that comparison. I will not be going off on a tangent on how the Meade f/8 10" ACF is far superior/inferior to the Celestron EdgeHD 11" SCT because that has no bearing on the topic.

Again the purpose here is to provide information to others thinking about either scope.

First up some quick data:

Mewlon Family Specifications
Mewlon 210 Owners Manual
Mewlon 250 Owners Manual

The reason why I went with the Mewlon series of scopes is because I wanted the very best Reflector scope I could find that was in a similar footprint of a SCT.

Don't get me wrong. I loved my SCT's they were fantastic performers and did everything advertised. I was fortunate to have very good mirror samples on mine. However I also observe from Southern California which means that temperatures can swing from day to night. Not as much as other locations but still enough that I was waiting on cool down for my scopes. And my observing sessions tend to be very short due to life happening. So I wanted something that would give me the refractor like views of the Edge series of SCT, the ability to go deep like the Edge, but that would cool much faster and stay that way with less intervention.

The Mewlon 210 was the ideal scope for this. It is light enough to go to the field easily, its mirror quality was top notch, its mechanical quality was acceptable (more in a moment), and it cooled to the point where I wasn't seeing wooly stars (I HATE wooly stars) in half the time of my SCT even with the Deep Space Products TEMPest fans (I highly recommend these for your Edge SCT).

I usually pair my 210 up with my TSA 120 when I am at dark sites and structure my 4-6 hour observing session around objects that each scope excels on. I have found the 210 punches way above its weight class delivering refractor like views to the edge of the field when cooled in a detail level similar to a 9-10" SCT. Especially on planets. I used to not be a big fan of Jupiter. It was my 5th favorite planet after Saturn, Mars, Uranus, and Neptune. Until I got a look at it with the 210 in good stable air. It was amazing the detail and the colors I could see. Ditto on the moon. I would usually spend only a few 10's of minutes at most on the moon. Until I started using the 210. Now I can find myself loosing track of time and spending hours on it without realizing it. Globular clusters are quite nice with individual stars easily resolvable. Same with small planetary nebulae and the appropriate filters. Really really nice to look at.

I found I liked the 210 so much that I decided that I was willing to spend the substantially extra amount of money to down size from the EdgeHD 11" with excellent mirrors I had to the 10" Mewlon 250. Fortunately my local shop, Woodland Hills Camera and Telescope, was very helpful giving me a very generous trade in value for the Edge so I could (barely) afford the 250.

[dr.who]

My understanding of the collimation process for a M210 per a conversation with Takahashi America:

1. Get a 2' X 2' white sheet of cardboard or poster board
2. Use a ruler or T Square to mark the center of the paper
3. Drill a 3/8" hole in the center of the paper
4. Mount the OTA on a mount or in a position where you can comfortably look in the tube
5. Shine a light so you can see inside the tube
6. Sit or stand so the secondary is at eye level
7. Move so you are approximately 4' away from the tube (50" is specified)
8. Look in the tube so you can see the spider vanes and their reflection in the primary
9. If you are at the right level you will also see the black donut that is the baffle tube
10. Move backward and forward until the secondary, main secondary nut and baffle tube merge
11. Once step 10 is done get the card stock and look through the hole as you did in step 10
12. You should see 3 vanes if collimation is good
13 If you see six vanes adjust by 1/8 turn the collimation nuts with a 2.5mm hex key until you see three vanes.
14. Wreck the collimation further, curse and make rude hand gestures at the scope, CN, me, Takahashi, and anyone else that comes to mind.
15. Finally give up in utter frustration
16. Buy a Hotech Deluxe CT Collimator
17. Repeat steps 14 and 15 with Hotech Collimator and move to step 18
18. Put the scope on a shelf to wait for good seeing and several hours to fiddle with it using Polaris and a high power EP

Honestly just skip to #18

The nuts on the M210 are very tight and can/will squeak on you when you turn them. They need very little turning to make big adjustments so be advised of that when you play with it. In the case of my own M210 it has held collimation very very well in spite of my doing my level best to ruin it by driving recklessly at high speeds into turns and over bumps as well as unpaved roads so the good news is once you have done this and gotten it dialed in you likely will not have to do it very often.

The Takahashi Collimation scope DOES NOT work on the Mewlon 210. It may work on the 250. I won't know that until I get my 250 out of the box, on the bench, and get a look to see if there is actually a center spot. Supposedly there is.

[dr.who]

There is a Feathertouch focuser for the Mewlon 210. What you want is:

FTF2008 2.0" focuser with 0.8" drawtube
A20-261 adapter to attach it

There is enough back focus to use most eyepieces wit this setup.

The Mewlon 210 has enough back focus for me to use a Tele Vue Binoviewer with Baader T2 1.25" setup, 1.25x Glass Path Corrector, and the stock fitting on the Mewlon. Here is an image of the Mewlon with the BV and other kit.

[dr.who]

One of the things I cannot stand about the Mewlon family is the lack of RACI finderscope. I find it a royal PITA to bend myself into positions to use the finder. Fortunately there is a very nice solution to this. It is made by Telescope Service aka Telescope Express in Germany. Here is the link to it. It is a right angle polar scope adapter:

http://www.teleskop-...inderscope.html

And here it is on my 210. Wonderful to use. The stock one works fine. No special machining needed by the folks at TE.

[dr.who]

I use a Losmandy Universal D Plate on all of my scopes now. The one I use on the 210 and will use on the 250 is the large one at 13" long. I like it because it has inch marks on it in 1/2 inch increments making finding the same spot for balance much easier.

The Mewlon 250 requires scope rings. They are not included in the $9,500 USD price of the 250. They will cost you an additional $500ish dollars. From memory $580. Then you have to spend another $250ish dollars on the special Takahashi Mounting Plate. While I was at peace with the Mewlon 250 cost and my local store, Woodland Hills Camera and Telescope, was very accommodating with me providing me an excellent value on the trade in for my excellent mirror EdgeHD 11" SCT I am still very much Irish and spending the equivalent to a nice APO refractor so I could have the pleasure of using special Takahashi rings and mount plate just wasn't in the cards.

Fortunately Parallax is substantially cheaper. For $260 they are making custom rings for me. And the D plate is about another $80. The outer diameter of the Mewlon 250 is 280cm so there is a possibility that the Orion or Skywatcher 10" imaging Newtonian Astrograph rings will also work.

My 250 is waiting on these rings so I can get first light with it.

[dr.who]

The Mewlon 210 has mirror shift. I am not sure it would be possible to engineer it out for a price point that made it acceptable. However the mirror shift is substantially less than any of the SCT's I have worked with. So if mirror shift is a problem for you then the 210 is likely not the scope for you. But then neither are any other SCT's. Mine has very little but it is there.

[waso29]

tak green r&p focuser is a good add-on

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[waso29]

for flatter and faster imaging, the tak µ 0.8x flattener/reducer works well.

add wide t-ring and slip it into 2 inch opening.

note: there is undercut that might not work well with compression ring adapters.

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[Tyson M]

Awesome info of first hand experience.

 

The Mewlon definitely sounds like a dream scope. 

 

I don't find much of an issue with thermals even with the closed tube up north.

 

But, refractor like views out of a large cat......now that sounds appealing.

 

Everyone who gets one here says the same thing...I hope I am fortunate to look through and/or own one

 

That 250mm- punching above its weight and refractor like? Now that would be a treat. Looking forward to first light. 

[waso29]

for those with portable mounts and find 8kg too much, should try the baby µ:

http://www.cloudynig...ew-mewlon-180c/

[Bill Barlow]

Dr. Who, is the TS fix for the 8x50 straight through Tak finder a RACI prism?  Does it attach using the Tak thumbscrew at the end of the focuser?  With the new Mewlon 180 having a 6x30 finder scope, I wonder if TS makes a 30mm adapter like the one for the 50mm finder scope.  Thanks for the informative posts.

 

Bill

[dr.who]

Hi Bill. I will shoot some more images for you. The back end of the 180 finder is likely the same size so the TE unit should fit. 

 

My 210 with D plate weighs 20 lbs or 9 kg not 8 kg per Takahashi. It would be lighter with a Vixen rail but I am standardized on the D plate. 

 

Thank you Waso! Good information! Please everyone feel free to add on!

[The Ardent]

I just ordered two of these. How well does the 1x-2x feature work?

One of the things I cannot stand about the Mewlon family is the lack of RACI finderscope. I find it a royal PITA to bend myself into positions to use the finder. Fortunately there is a very nice solution to this. It is made by Telescope Service aka Telescope Express in Germany. Here is the link to it. It is a right angle polar scope adapter:

http://www.teleskop-...inderscope.html

[bobhen]

I’ve had my Mewlon 210 for a year…

 

Here in PA, and I presume anywhere above the Mason Dixon line, if you bring your scope from inside the house to the outside, ALL Cassegrains (Mewlons, SCTs, Maksutovs, etc.) need some type of cooling and acclamation assistance (fans of some type) or you might be waiting a very long time to use any of the above for high power viewing.

 

The Mewlon 250 has fans but the Melon 210 (or the new 180) do not.

 

I found that by adding fans to my 210 they helped with initial acclimation but more importantly they also kept heat plumes from reforming during the night if temperatures continued to fall, as they tend to do here in PA. Fans that can be used while observing are a big plus in this regard. Newtonian owners add and use fans without a second thought and Newtonians have open tubes. So just because your Mewlon or other Cassegrain has an open tube does not mean that you are exempt from cooling issues.

 

The finders on the 210 and 250 can be removed if you remove the telescope’s back plate and I believe (?) Synta finder shoes can be made to work and Synta finders can then be added. I use my Mewlon 210 on a side-by-side ALT/AZ mount so other scopes can serve as finders or the DSC are used or my AVX GEM GOTO mount is used to help find difficult objects. The AVX holds the Mewlon 210 perfectly.

 

I found that with my 210 an after market focuser like the FT was not absolutely needed but an aftermarket focuser is really nice to have for very fine focusing and I added a Moonlite to my 210 and I like it.

 

I found that collimation difficulty or ease was about the same as with an SCT but you do have to make very small moves and listen for that squeak! Also don’t drop the wrench down the tube or you will have a very bad day. My 210 was not far off and it took me about 5 to 10 minutes to collimate it when it arrived. Collimation holds really well.

 

What has impressed me so far with the 210:

 

Contrast for a compound mirror scope is off the charts. This is plainly obvious and not subtle when compared to SCTs.

 

Sharpness is also excellent with in-focus stars sharper and better defined when compared to SCTs. The stars are not as sharp as in my TSA 120 but they are very sharp and well defined for a compound scope falling between the refractor and SCTs.

 

Portability and ease-of-use are excellent.

Deep Sky reach seems to punch above its weight, likely do to the wonderful contrast and sharpness. Mewlons are usually promoted as lunar/planetary scopes but the deep sky views (for objects that fit in the field of course) are bright, color free, sharp, and contrasty!

 

The spider veins are not intrusive even when observing deep sky or bright Jupiter. But as with all scopes that use spiders, they can impact double star observing.

 

Here in PA seeing limits high power viewing (that’s why I also have the TSA 120) but on above average nights the Mewlon 210 just kills on the moon delivering a view that is solid and sharply defined and unlike the view compared to SCTs, which have more light spray that can soften very fine details.

 

All scopes have pluses and minuses, but for my needs, and after a year, the Mewlon’s pluses have outweighed its few niggles.

 

Hope my experience helps with those who are considering a Mewlon 210.

 

I’ve posted this image before but take notice of the fan ports and Moonlite on the back of the Mewlon 210.

 

Bob

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[ckwastro]

I can attest to the excellent contrast with the Mewlon series. My 210 optically is far and away the finest folded design I've ever used.  I've been considering the jump to the 250 as I believe it is mechanically superior to the smaller models. But I'm not sure it is worth the cost to do that, especially since I already have a 12.5 Teeter truss dob with a nice Ostahowski quartz mirror. The 210 fits in the progression much better. 

 

Unfortunately I can also attest to the mirror-flop. Mine is nearly as bad as an SCT, & it drives me nuts at higher mags. I really wish they would have employed the moving secondary focuser like they have on the 250 & 300 models. I've held off adding a Moonlite or FT focuser because I was concerned about adding weight to an already back-heavy scope (GEM mounted), and also the back-focus issues. I make heavy use of a binoviewer and was concerned it might be a problem. For those of you who have added the after-market focuser are there any balance issues for you? Anyone else have any back-focus problems or does the ability to move the position of the primary with the stock focuser alleviate that particular problem?  Thanks!  

[ckwastro]

One of the things I cannot stand about the Mewlon family is the lack of RACI finderscope. I find it a royal PITA to bend myself into positions to use the finder. Fortunately there is a very nice solution to this. It is made by Telescope Service aka Telescope Express in Germany. Here is the link to it. It is a right angle polar scope adapter:

http://www.teleskop-...inderscope.html

And here it is on my 210. Wonderful to use. The stock one works fine. No special machining needed by the folks at TE.
 

 

Completely agree.  Thanks for the info on this!

[bobhen]

I can attest to the excellent contrast with the Mewlon series. My 210 optically is far and away the finest folded design I've ever used.  I've been considering the jump to the 250 as I believe it is mechanically superior to the smaller models. But I'm not sure it is worth the cost to do that, especially since I already have a 12.5 Teeter truss dob with a nice Ostahowski quartz mirror. The 210 fits in the progression much better. 

 

Unfortunately I can also attest to the mirror-flop. Mine is nearly as bad as an SCT, & it drives me nuts at higher mags. I really wish they would have employed the moving secondary focuser like they have on the 250 & 300 models. I've held off adding a Moonlite or FT focuser because I was concerned about adding weight to an already back-heavy scope (GEM mounted), and also the back-focus issues. I make heavy use of a binoviewer and was concerned it might be a problem. For those of you who have added the after-market focuser are there any balance issues for you? Anyone else have any back-focus problems or does the ability to move the position of the primary with the stock focuser alleviate that particular problem?  Thanks!  

With my 210 and the addition of the somewhat heavier Moonlite focuser, there are no balance issues with either my AVX GEM or DSV-3 alt/az mount. The Mewlon 210 with diagonal and even a heavy ES 24mm 2” eyepiece balances nicely. SCTs are also back heavy and people use aftermarket focuses without any real problems.

 

I have not used a binoviewer with the scope.

 

I have used a .7 reducer and a NVD Micro image intensifier eyepiece and that combination requires a lot of in-focus but the Micro with the reducer still comes to focus with a 2” diagonal in the 210.

 

My example had little image shift to start with and the after market focusers take care of that and also add another level of focus precision.

 

Bob

[ckwastro]

Great information. Thanks Bob!  If I can eliminate that issue then there isn't much sense in upgrading. The mirror on my 210 is outstanding, and it's long paid for so I'd rather do a couple upgrades than spring for a new OTA.  Appreciate the help.  

[mich_al]

I use a Losmandy Universal D Plate on all of my scopes now. The one I use on the 210 and will use on the 250 is the large one at 13" long. I like it because it has inch marks on it in 1/2 inch increments making finding the same spot for balance much easier.

The Mewlon 250 requires scope rings. They are not included in the $9,500 USD price of the 250. They will cost you an additional $500ish dollars. From memory $580. Then you have to spend another $250ish dollars on the special Takahashi Mounting Plate. While I was at peace with the Mewlon 250 cost and my local store, Woodland Hills Camera and Telescope, was very accommodating with me providing me an excellent value on the trade in for my excellent mirror EdgeHD 11" SCT I am still very much Irish and spending the equivalent to a nice APO refractor so I could have the pleasure of using special Takahashi rings and mount plate just wasn't in the cards.

Fortunately Parallax is substantially cheaper. For $260 they are making custom rings for me. And the D plate is about another $80. The outer diameter of the Mewlon 250 is 280cm so there is a possibility that the Orion or Skywatcher 10" imaging Newtonian Astrograph rings will also work.

My 250 is waiting on these rings so I can get first light with it.

 

 

FWIW Robin Casaday made a Losmandy D plate drilled for the 250.

[dr.who]

I just ordered two of these. How well does the 1x-2x feature work?

I am sorry I don't know. I never used the 2x. It does do a great job of passing light and the helical focuser is handy.

[dr.who]

I do not recommend Bobs Knobs for these scopes. From an authoritative source they actually can cause collimation to slip and thus make it necessary to collimate more often.

[dr.who]

As soon as I get the FT focuser I will try it with my BV setup. My guess is that you will be fine if you use the Baader system and a 1.25x GPC. There was a good amount of in travel left with mine when I tried it and the TV's have one of the longest light paths of all binoviewers coming in at 132mm

[dr.who]

As soon as the rings get here I will do a 210/250 comparison from heavy LP and dark skies. I was hesitant to get the 250 because the 210 was within loud voice not shouting distance of my 11" SCT and for sure the clarity and contrast were superior.

[Bill Barlow]

Bobhen, if you remove the scopes back plate/rear cell to remove the finder scope, won't you risk messing up the collimation or optical alignment?  

 

Bill

[bobhen]

Bobhen, if you remove the scopes back plate/rear cell to remove the finder scope, won't you risk messing up the collimation or optical alignment?  

 

Bill

The Mewlons are engineered to have the back plate removed for easy access to the mirror for cleaning while keeping the collimation close. You will have to tweak collimation after cleaning but it shouldn’t be that far off.

 

HERE is a link to a photo that illustrates the point.

 

Bob

Edited by bobhen, 13 November 2016 - 04:12 PM.