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Information on the Takahashi Mewlon 210 and Mewlon 250

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413 replies to this topic

#401 krakatoa1883

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Posted 16 January 2020 - 08:42 AM

Since excellent collimation is a huge factor with the performance of a Mewlon, curious to know how many use the Takahashi collimation scope to achieve this?

I had one but I found it of limited usefulness except for reassembling the secondary mirror after maintenance or cleaning. It allows an approximate collimation that however needs to be refined on a star at high power. Eventually I replaced it with this one, much better and also cheaper.



#402 nva

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Posted 20 January 2020 - 03:47 AM

Silly question. I've never actually swapped out a dovetail on any of my telescopes before. The saddle on my mount is going to wear away at the base of the telescope (I have one of the universal saddles and the vixen dovetail is deep so the saddle rubs against the telescope). I got the losmandy universal 7 inch dovetail but included screws are way too big and the stock screws (they seem like m4 right?) are not long enough (there is not a tremendous amount of travel in them in the first place). I would have to buy longer screws and place them both in slots (which seem pretty wide, I could/may have to use a washer). Am I missing anything here? Should I have chosen some other dovetail?



#403 Astrojedi

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Posted 22 January 2020 - 02:01 PM

I understand the dilemma and yes, you are right about a few of the Mewlon's being bought and sold but it also doesn't surprise me either. It's a very rewarding telescope but you have to play by its rules. It doesn't do it for them on its own and if others don't have the right mix of needs for a Mewlon, then a lens may be a more appropriate choice. I've had several friends that acquired Mewlon's only to fail miserably. I've seen them come and go like another day. One was a Mewlon 300 which a friend sold just a month later. He didn't follow the tips that were given to him. I have another friend who bought a Mewlon 250. He sold it just three months later. He too didn't follow the guidelines. I just sat by and waited to see how long these guys would last with this scope and just said it's a matter of time until they crack. I know another who had an M210 and sold it just a few months later as well. The number one problem isn't the scope, it's the observer. By observer I mean their own ability or inability to understand how scopes behave in their climates, level of patience, seeing conditions, understanding temperatures, proper setup, collimation, fans etc. This is why I'm all about one's experiences in the field. Enthusiasts get too lost in stats and marketing hype but they rarely look in the mirror at their own misunderstandings. We live in a time where enthusiasts want things quick and now. These scopes are not for those kind of individuals. What I can say though is that for those looking into this design in a portable and more forgiving package, the M180 is the best choice of them all. I like it even more-so than the M210. 

I have never owned a Mewlon but this sounds like a very difficult to use scope.



#404 Astrojedi

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Posted 22 January 2020 - 02:05 PM

I appreciate your consistence with tone and approach. The bulk of my consideration has been focused on the 210. Context would be I've probably read all the posts and threads with the word mewlon in them but I've focused on the ones with the 210 and 180 and sometimes gloss over the 250-300 posts as they are less relevant to my considerations and I've seen your current youtube video lineup. When you read the posts over the years the telescope can be VERY polarizing at least to those post about it, lots of people (maybe a dozen?) immediately got rid of this scope after purchase, some its obviously from problems with collimation, some acclimation, for some its unclear but I would wager its a mix of both. Contextually you could blame this on inexperience in some of these cases but the scope has even defeated those who seem to have plenty of it.

 

Anyway, seeing here is average I am generally satisfied with it If I had to pickering it 6 on most nights I'm out, I'm under the jet stream, I have seasons, night deltas could range from 10-20 degrees but are usually more linear at 1-2 degrees per hour, we have humidity and temps are often near the dew point so dew/frost happen. I have considerable light pollution being in a major metro area. The tote idea is inspired from the 2012 mewlon review on cloudy nights and seemed simple and safe and could be done by a family member with instruction even if I wasn't home.

 

Your welcome to dissemble, the scope meets all my requirements except its not optimal for my use case (why I have a refractor) I was just curious if anyone thinks it could meet it with a reasonable amount of preparation with the hesitation I mention from my first paragraph.  I guess I really need to think about the 180? Do you think it will fit the use case that much better? 

I strongly believe that the scopes we use the most are ones that suit our observing conditions and preferences. While the Mewlons sound like good scopes I honestly think for you a 5" or smaller refractor makes more sense. In fact the ease of use is probably the most valuable trait of a refractor.



#405 ckwastro

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Posted 22 January 2020 - 05:28 PM

I have never owned a Mewlon but this sounds like a very difficult to use scope.

Is really not difficult at all, and in fact is quite easy to use. Like any other scope, you just have to plan properly. I’ve had my 1997 version 210 coming up on 12 years. I’m the second owner. It was properly collimated when I bought it, and I have not had to touch it at all. So while it might be a little work to dial it in if you need to, once it’s collimated, it stays put. At least that has been my experience. 
 

Mine has no removable back plate, nor does it have any fans, so I have to plan a little when I use it. Not a big deal. I usually set it up on the weekends, and leave it out and covered if I know the weather is going to be good. The first night I will try to give it at least three hours to acclimate. Not much different than setting up a big dob well before sunset. If I know I won’t have that kind of time, I’ll setup the Stowaway instead. 



#406 Lola Bruce

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Posted 22 January 2020 - 07:04 PM

Any large mirror scope requires thermal equilibrium. Mewlons as a rule give such a sharp and contrasty view that it can very noticeable when they are not equalized to ambient temps. Lesser scopes may not be as apparently sensitive to temperature but I have found they just can't reach the same quality of view. When purchased I carefully collimated my 250 Mewlon and it has not needed redone in four years. A touch-up on a good night on a star would be nice but my eyes are no longer good enough to do the scope justice.

Like an AstroPhysics mount they just work.

 

Bruce


Edited by Lola Bruce, 23 January 2020 - 02:09 PM.

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#407 Larloch

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Posted 23 January 2020 - 06:05 AM

I have never owned a Mewlon but this sounds like a very difficult to use scope.

No it isn't. I was barely an experinced observer when I got mine. But before that, I read every single forum post and advice I found online about the scope. When it finally arrived, I re-read all of those posts, and then applied them in the field, and at my little backyard. Suprisingly, it wasn't that difficult at all. Only patience and practice needed for success – and for a second time "WOW"-feeling.


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#408 AnakChan

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Posted 23 January 2020 - 06:29 AM

Of the 3 primary scopes (FSQ85ED, 125SDP, 250CRS), the Mewlon 250CRS gets the most use. I’m particularly curious what the difficulty is using or maintaining a Mewlon? If it’s collimation, mine has held its collimation in 5 years of ownership, and I have to travel 100+km to get out to the remote site.


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#409 dr.who

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Posted 23 January 2020 - 12:27 PM

 The statement that the 210 or the 250 are hard scopes to maintain is not true. They are very easy to maintain. And to use. Daniel is a very experienced observer who wants as perfect a view as possible. Ergo he goes extra lengths to achieve the full capacity of the Mewlon.

 

If you are wanting the best view possible, cool the mirror until it reaches TE. Once there and if it is properly collimate you will get a view that is equal to or better than what you would get with a Zambuto mirror. I did a comparison between my Teeter 12.5” with a Zambuto and my 210 as well as 250. When all three were properly collimated and cooled the views in the Mewlons surpassed the Zambuto by a very small margin. Granted this is a single sample of each but the Zambuto mirror I had was a well figured one. I was also accounting for aperture difference. The Zambuto had more resolution and brightness overall compared to the Mewlon’s but contrast, coloration, etc were slightly better. Not so much so that it was a very noticeable difference but it was there.

 

Regardless, if you want one of the best reflectors you can get that is compact compared to a Dob or even a Newt and readily available (The AP is likely better but at a $25,000 price tag for a 10” and very hard to find. I say likely because I haven’t had a chance to look through one) then a Mewlon is the best option for the price out there. 


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#410 nva

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Posted 24 January 2020 - 08:44 AM

The scope provides fantastic views, the 210 is reminiscent of a 10 inch newt/dob with the difference mainly being in focal ratio. I think the pain and suffering of this scope is simply due to its folded optical design with the secondary providing 4x magnification. This makes collimation more difficult and would that not magnify tube currents all the same? I only have a few hours under my belt at this time but it seems like a keeper, ready for deep sky in 15-30 minutes, medium-high power after probably an hour and on the moon 500x (60x/inch) was pretty sharp after 90 minutes with 700x(80x/inch) being slightly soft and wavy which was probably the atmosphere. Works great on a AZ Mount Pro. Mine arrived with the primary and finder scope in perfect alignment and collimation.

Edited by nva, 24 January 2020 - 09:47 AM.


#411 amys

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Posted 24 January 2020 - 09:21 AM

Nick - are you trying to covert the straight through finder that comes with the scope to a right angle one via the Telescope Service adapter or are you trying to add another finderscope to the Mewlon?

If the former then you are fine. No Skywatcher(technically Vixen)/Losmandy adapters or rails needed. Have them shave 1mm off the inner diameter of the adapter so it will for sure fit. They will do that for you. If it is the latter, why would you want a second finder? The one that comes with the scope works really well and is already zeroed in to the scope so there is no need to adjust it.

If you are asking what mounting rail to use, you can use a Vixen or Losmandy D rail/plate. It will just depend on what saddle your mount has. Go with the Universal rail in eith Vixen or Losmandy D to make sure everything lines up right.

Well, after ordering the smaller one by mistake, I just received the larger one and found that it too is too small to fit over the Tax finder scope eyepiece.  I didn't see this suggestion of asking TS to shave the inner diameter by 1mm.  So now I'm stuck with 2 of these adapters that don't fit.  bawling.gif



#412 greenstars3

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Posted 24 January 2020 - 02:45 PM

amys

 

The smaller one fits on the 6x30 finder, if someone wants to mount it and leave it they will need some shims, email TS and tell them that your larger one will not fit, maybe they will take it back. I have the u180 and find that the thing is best used as needed and not attached, the outer FOV is not in focus enough for my taste to leave it on all the time but it is fine when you don't want to break your neck while using the finder. Maybe you can find a machine shop that would be able to do the deed for you and mill this larger one to fit on the larger finder.

 

As to adapters to put on your dovetail, ADM has a Losmandy style one that screws onto the mounting gear supplied by Tak

 

Robert

 

edit: it might be easier to have a machine shop make a new ring that screws onto the Tak finder than have the TS right angle ground down, just replace the Tak ring with the new one and you still have astro equipment that has  not been modified 


Edited by greenstars3, 24 January 2020 - 03:07 PM.


#413 dr.who

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Posted 24 January 2020 - 08:52 PM

Or take a dremmel and grind out about 1mm or metal. Both options (grinding or asking for a return) should work. 



#414 tegea

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Posted 05 February 2020 - 06:36 PM

I've been following this thread for months and even participated to it to share my experience with my mewlons 210 and 250. I now only have the 250 and sold the 210 to a friend.
My mewlon 250 is a classic non CRS one, and I'm very happy with it.
I was wondering if it was worth purchasing the CRS corrector. Did some of you did that and with what result ? Is the scope still as sharp as before on axis ? Is there an effect on thermal equilibrium ?
I read Daniel saying that the corrector helped reducing the baffle turbulences.

Edited by tegea, 05 February 2020 - 06:37 PM.



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