An idiot's guide to the Takahashi Mewlon 210 and 250

[Dr Strange]

Well since I played Rugby both at Uni and after until becoming too injured to continue I am pretty ugly and not very bright (the good looking smart ones play Cricket or Football) so I qualify for that Idiot tag. Hence the title of this thread. I plan to do several other "Idiot" threads on my other equipment as well since it has been my experience that some of the information I had to work hard at finding would be beneficial to others coming after me. Unless of course it is just a case where I am an idiot and you lot have already gotten these things down pat in which case I will laugh at my own stupidity and get on with things. Note: I originally posted this on the US site cloudynights.com but thought it might be helpful here too. 

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. From my research I found out there are only 40 Mewlon 210's made per year. Of those 40, 20 go to the USA and the rest go to other countries. 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  so that hopefully someone like me coming along behind me doesn't have to go through the learning curve I did.

I have done side by side comparisons between an 8"/203mm, 11"/279mm, and 14"/356mm Celestron EdgeHD SCT's and the Mewlon 210 and 250 so I will be mentioning what I found in that comparison. 

First up some quick data:

Mewlon Family Specifications:
Mewlon 210
210mm/8.27in aperture
f/11.5
32% CO
2,415mm focal length
13.4 limiting magnitude
18mm image circle
210mm back focus
Primary mirror 220mm elliptical Pyrex aluminized multi coating
Secondary mirror 65mm spherical Pyrex aluminzied multi coating
244mm/9.6in diameter
700mm/27.56in length
9 kg/19.8 lbs
7x50 finder 6.3 degree FOV
 
Mewlon 250 CRS (current production model)
f/10
250mm/9.84in aperture
28% CO
2,500mm focal length
13.8 limiting magnitude
21mm image circle
210mm back focus
Primary mirror 260mm elliptical Pyrex aluminized multi coating
Secondary mirror 72mm spherical Pyrex aluminized multi coating
280mm/11in diameter
850mm/33.47in length
15 kg/33 lbs
7x50 finder 6.3 degree FOV with recticle illuminator
 
NOTE:  Takahashi masked off the outer 10 mm of the primary mirror in order to eliminate the coma problem that was noted in the original Dall-Kirkham design.

Mewlon Family system charts:
https://www.takahashi-europe.com/en/mewlon.systemcharts.php

One thing I find frustrating about any Takahashi telescope is the various bits and bobs you need to make the <REMOVED> thing work! So much so that I dumped my FSQ-85. Trying to get it to work with my CCD was an exercise in almost a s**ual fetish where I felt like Merv the Perv, wanted to wash my hands afterwards, and never discuss it in polite company. It was also expensive to do. In comparison the Tele Vue bits were only $140 USD and that was for all the spacers they made. Half of which I don't need but it was cheaper to order the complete kit. Remember I am Irish so cheap, like the budgie. Speaking of which did you know how copper wire was invented? Two Irishmen fighting over a penny!

Mewlon 210 Owners Manual:
https://www.astronomy-electronics-centre.com.au/instruction_manuals/Mewlon 210.pdf

Mewlon 250 Owners Manual:
https://www.astronomy-electronics-centre.com.au/instruction_manuals/Mewlon 250.pdf

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 even using the Deep Space Products TEMPest fans, something I highly recommend since they cut cooling time by about 1/2 and keep the scope at thermal equilibrium while being able to observe too. I like the EdgeHD scopes for visual use because they can be fitted with the TEMPest fans and they provide refractor like views to the edge of the field. A real plus. 

My observing sessions tend to be very short due to life happening. During the week about 1 or so hours (unless I lose track of time because I am so into observing at which She Who Must Be Obeyed gets quite cross because I am a zombie the next day) and about 4-6 hours from a dark sky/during the weekends. 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, and have the best mirrors in the form factor of the SCT that were commercially available with a relatively short lead time. TEC and Intes Mak's and the like are another example of excellent mirror quality but can only be found now on the used market and then rarely.
 
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 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 was very helpful giving me a very generous trade in value for the Edge so I could (barely) afford the 250. Unless you are for sure wanting to have the very best out there and have the disposable income (for me it was the trade in on my Edge plus the fact that I have no other hobbies, was willing to bring my lunch to work and save money that way, and convince She Who Must Be Obeyed that it was a good way to keep me out of the local pub's) for it, I would recommend the 210 or even the 180 over the 250. The 250 really needs good seeing conditions to really bring out its full potential. 

A note on collimation. The Mellon's hold their collimation really well. So far I haven't had to collimate either. However being the 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 M210/250 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 because of a lack of a center spot. Supposedly there is one on the 250. I have the CRS and after just checking to confirm, there isn't one on mine. There might be one on the older models or more recent models but there isn't on mine ergo no Collimation Scope for me. Collimation is not hard with these so save the money since you will have to finish collimation on a star anyway so why bother? 

There is a Feathertouch focuser for the Mewlon 210 and 250. 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. I have this on my 250 because I *HATE* the electronic focuser. More on this in a minute. 

The Mewlon 210/250 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 210 with the BV and other kit:

Mewlon 210 baader 2 inch prism diag TV BV 1.25 GPC 

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:

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p5224_PFZSLOS-90--diagonal-for-your-Losmandy-Astrotrac-Polar-Finderscope.html

And here are photos of it on my 210:

Mewlon 210 with finder close up

Mewlon 210 with finder 1

Make sure to tell the folks at TE that it is for a Mewlon so they can dremmel out the fitting since this is designed by them for a polar scope. This works well on PS's too.

I use a Losmandy Universal D Plate on all of my scopes now. The one I use on the 210 and  250 is the large one at 13"/33cm long. I like it because it has inch/cm 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 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"/2o0mm imaging Newtonian Astrograph rings will also work.

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. 

I strongly 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. 

Coma was minimal and in only the outer 5-10% of edge of the total field of view using Ethos eyepieces in the 17mm and below range in the 210 when the 210 was properly cooled and had (still does) very good collimation. I am sensitive to coma and can't stand it when I look in a scope. Thus why I am such a APO refractor fan. And why I have the Mewlon's. They have the least amount of coma I have seen in a reflecting scope. My old UC15 at f/4.2 had it badly to my eyes (I could see it easily but others sometimes did not as they were less sensitive to it) so I had to use a Paracorr with it at all times or else I would get very frustrated since I hate seagull stars.

The other thing that drives me to distraction is wooly fuzzy flairing stars. Something I would get in my EdgeHD scopes if they were not cooled well enough. Again why I am such a refractor guy. And something that is reduced to near zero much quicker in the Mewlon's than the closed cell SCT's. 

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 9.25"/236mm SCT. Especially on planets. I used to not be a big fan of Jupiter. It was my 5th favorite planet after Saturn, Uranus, Neptune, and Mars. 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. Plus the GRS. I had only seen the GRS in my Obsession UC15. 

And the same applied to 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.

This is pretty much what the 250 delivers. However there is 2"/51cm of more aperture. That is a good amount of aperture increase even with the "wow" factor being defined by many as 3"/76mm in order to get that "wow" factor visually in a reflector. Another key point of the 250 is that with the $500 USD reducer that brings the scope down to f/8, imaging is much easier because of the active cooling and electronic focuser. If you are an imager then this may make the 250 an easier decision though you will need/want a EQ6-R mount of bigger to do so. Visually (since I am not yet good enough to be imaging at 2,500mm focal length) there was a very noticeable increase in brightness in the small objects I look at as well as the planets/moon. 

Is this worth the $6,500 extra the 250 costs? Only you know the answer to that for your given circumstances. To me it was, but I was able to get a very good deal on my EdgeHD 11 that brought that $9,500 cost down quite a bit and I have no other hobbies.

More on my likes and dislikes about the 250. I liked the fans. I am mostly ambivalent with a touch of hatred towards the motorized focuser. So I am moving off from the I positively *HATE* the thing at this point. It focused acceptably though I had to go inside and outside of focus to tell if things were focused properly. Something I am not used to with my "regular" focusers.  It still frustrates me that the focuser is a major single point of failure that could render the scope useless. That is just bad engineering in my book.
 
What was especially frustrating last night was that I had the unit plugged into a 110-120v plug on my 12v battery pack  and the plug kept coming loose from the controller. Also with all the cables (power for the mount, the hand controller for the mount, and the controller for the scope) things got a bit tangled which was a frustration point. For sure I will be putting the 9v battery in there if I use the bloody thing. I found that if I had the plug come loose then plugged it back in the scope would unfocus itself by a decent bit. No idea why it does this. Anyone know?
 
I did put the above mentioned Feathertouch focuser on it so I can abandon the motorized focuser completely. It is a joy.
 
And a more detailed observing report using the 250. Note the 210 is similar just not a bright and some less detail. I am in a barely red mostly white LP zone which sucks for me but it is what it is. The only EP I used was the 17mm Ethos which gave me 147x magnification on targets. Speaking of which the targets in order were:
 
SAO 113271 Betelgeuse
NGC 1976 Orion Nebula
NGC 224 Andromeda galaxy
Uranus
NGC 752 Open cluster in Andromeda
NGC 457 Dragonfly cluster
 
Betelgeuse - Bright, big, a bit soft, and a bit woolly. And diffraction spikes which don't bother me. It was shortly after the fans were on so the scope was no where near TE and that's fine. It was better than what I would get in my SCT's out of the box and even about 15-20 minutes in with TEMPest fans.
 
Orion Nebula - Also a bit soft but clear nebulosity and the A-C stars clearly visible. Again too close to startup to provide a good view. Sadly when I used my TEC 140 later on in this evenings session (it was first light for it and the scope has since been sold because the TOA 130 did better plus is air spaced since in the last couple years I have seen 7 different cases of oil settling/leaking in oil spaced scopes which scares me since both Roland Christian of Astro-Physics and Yuri Petronin of TEC are of an age where they are closer to the end of their respective journeys than the beginning so repair will be a question) I got the A-D stars with hints of E & F. I do love my refractors. And with it being open cluster season it is really a better time for them.
 
Andromeda galaxy - It was there. There was some hints of structure which was nice.
 
Uranus - Wow! A bright light blue ball! That was nice! And even through it was poor seeing I believe I could have pushed up to 250x with a 10mm Ethos and caught a good bit of detail. I didn't but I fully expect this scope to shine on the Moon and other planets. Update: It does.
 
Open cluster in Andromeda - Good number of stars in the field but couldn't get the whole cluster in the FOV. Saw some faint stuff in there. Caught what looked like a mag 8 and 9 or so double star in the cluster. Likely not a true double but they were close enough together for me to call it as such.
 
Dragonfly cluster - One of my personal favorites. Nice to see it again.
 

And lastly the front of both scopes:

Edited March 31, 2020 by Dr Strange
added photo of both scopes

[mikeDnight]

First things first. Rugby is by far the superior game than either boring cricket or girly football, and the rules are much simpler too, - whoever gets the ball dies!  I lost interest in cricket after seeing my 10 year old school friend Gary get his teeth smashed out with a cricket ball, and the teacher rush him off to hospital in his car. I've never played it since. And who in their right mind could ever like a game like football, when everyone blatantly cheats and no-one does anything about it. And watching grown men cry when they trip over a daisy is just too much to bare. Rugby is much more sivilised in my book. (I'm ugly with a bad back too!)

Now to the Mewlon.  What a brilliant choice. It will cool far more rapidly because of its open tube and will be both sharper and brighter than any catadioptric. I've never looked inside the Mewlon at its cell design, but Tak are renowned for making solid, well thought out mechanics. As for the focuser, well that's the mystery of Takahashi; nobody has a clue why everything is so complicated. As a visual instrument the Mewlon would generally leave Cat's in the dust, and if you only observe for short periods you'll appreciate their rapid cool down.

Personally I wouldn't bother with wide field eyepiece designs, but would use things like the 35mm Baader Eudiascopic,  and Takahashi LE's and longer Orthoscopics.

 

[JeremyS]

Lots of useful insights there, thank you.

So I’m now going to have to get an M210 to compliment my TSA 120???

🤣

 

 

[Dr Strange]

4 hours ago, mikeDnight said:

First things first. Rugby is by far the superior game than either boring cricket or girly football, and the rules are much simpler too, - whoever gets the ball dies!  I lost interest in cricket after seeing my 10 year old school friend Gary get his teeth smashed out with a cricket ball, and the teacher rush him off to hospital in his car. I've never played it since. And who in their right mind could ever like a game like football, when everyone blatantly cheats and no-one does anything about it. And watching grown men cry when they trip over a daisy is just too much to bare. Rugby is much more sivilised in my book. (I'm ugly with a bad back too!)

Now to the Mewlon.  What a brilliant choice. It will cool far more rapidly because of its open tube and will be both sharper and brighter than any catadioptric. I've never looked inside the Mewlon at its cell design, but Tak are renowned for making solid, well thought out mechanics. As for the focuser, well that's the mystery of Takahashi; nobody has a clue why everything is so complicated. As a visual instrument the Mewlon would generally leave Cat's in the dust, and if you only observe for short periods you'll appreciate their rapid cool down.

Personally I wouldn't bother with wide field eyepiece designs, but would use things like the 35mm Baader Eudiascopic,  and Takahashi LE's and longer Orthoscopics.

 

I give credit to the Footballers they make gobs of money and have to be really athletic with good endurance. It is a tough game to play. Otherwise they are a bunch of floppers. Rugby is a hooligan sport played by gentlemen. Football is a gentleman's sport played by hooligans.  

Ouch! on your friend! That sucks! 

A good trick for cooling of these scopes is to use a desk fan and a sheet. Cover the front opening with the sheet. Point the fan at the opening from about 300cm away blowing into the opening. That accelerates cooling significantly. The sheet keeps the dust out. 

What I like to do is to use my TSA for the fist half of my observing. Going after the wide field/big stuff. Within that time the Mewlon cools. After I complete the wide field/big stuff I swap out the Mewlon and go after planets and the small stuff or to go deep on the big stuff. Works really well.

[Dr Strange]

16 hours ago, mikeDnight said:

 

Personally I wouldn't bother with wide field eyepiece designs, but would use things like the 35mm Baader Eudiascopic,  and Takahashi LE's and longer Orthoscopics.

 

 

I find that seeing the barrel of the EP takes me out of the immersion and suspension of reality during observing. I used to use Ethos. In the last two weeks I found that I was using the Nagler's I have more than the Ethos. They are lighter, still mean I have to move my little bean head to see the barrel, and get that wide field experience I enjoy. So I sold off all my Ethos and switched completely to Naglers with a 24mm Panoptic in the mix and my biggest EP being the Holy Hand Grenade/ improvised club that is the 31 Nagler. With the 31 Nagler and a OIII filter I am able to get the entire Veil complex in my Tele Vue NP101is and it is amazing. The 31 however is huge and as noted I can use it as a improvised club if I need to beat off a wild animal or Football hooligan. 

Even with the narrow FOV of the Mewlon I find the TV's work really well. A good (and much less expensive) alternative is the Bresser/Explore Scientific 82 or 100 degree EP's. I owned the entire line of ES 82's except the 31. They were great. I updated to the TV's because at certain points of the year vendor's in the US would sell the EP's at cost which was a great discount. TV gave fee EP's, telescopes, etc to vendors who sold a certain amount of EP's in a given timeframe. Some vendors would sell them at cost because the value of the free stuff significantly outweighed the loss of profit by selling them at cost. I don't know if they do that anymore...

[Dr Strange]

16 hours ago, JeremyS said:

Lots of useful insights there, thank you.

So I’m now going to have to get an M210 to compliment my TSA 120???

🤣

 

 

Yes. If you check your TSA certificate it is actually an implied contract that you agree to when you buy the scope. Included in there is a paragraph that says if you buy/own a TSA-120 you are required to buy a M210 or 180 to compliment it. Sorry mate. You don't want to end up having to pay a Solicitor to try and litigate it. It is just cheaper and easier to bite the bullet and buy the Mewlon...

[Froeng]

On 01/04/2020 at 16:33, Dr Strange said:

Yes. If you check your TSA certificate it is actually an implied contract that you agree to when you buy the scope. Included in there is a paragraph that says if you buy/own a TSA-120 you are required to buy a M210 or 180 to compliment it. Sorry mate. You don't want to end up having to pay a Solicitor to try and litigate it. It is just cheaper and easier to bite the bullet and buy the Mewlon...

Good for Jeremy, he has fulfilled his contractual obligations! 🤣

[JeremyS]

2 minutes ago, Froeng said:

Good for Jeremy, he has fulfilled his contractual obligations! 🤣

Completely forgot about that! 🤣🤣🤣

[Alan White]

On 04/09/2022 at 10:50, JeremyS said:

Completely forgot about that! 🤣🤣🤣

Funny how things work through Jeremy.

Now if I can find some clauses in my paperwork with my kit .....

Edited September 5, 2022 by Alan White

[Stu]

How on earth did I miss this very informative and also amusing post/thread? Well thanks to the latest clarifications on vital contractual obligations I’ve now seen it. Thank you @Dr Strange, very useful although it may well indicate another Mewlon 210 for me in future which is painful for the wallet, but worthwhile I think 👍

[JeremyS]

57 minutes ago, Stu said:

thanks to the latest clarifications on vital contractual obligations I’ve now seen it. Thank you @Dr Strange, very useful although it may well indicate another Mewlon 210 for me in future which is painful for the wallet, but worthwhile I think 👍

So are you telling us you have a TSA 120 on order, Stu?

[Stu]

5 minutes ago, JeremyS said:

So are you telling us you have a TSA 120 on order, Stu?

No, absolutely not, but I would love to try one 👍

[Froeng]

be careful of the small print!

[HollyHound]

Does this apply in reverse if you own a Mewlon but not (yet) a TSA120 😬

[JeremyS]

8 hours ago, HollyHound said:

Does this apply in reverse if you own a Mewlon but not (yet) a TSA120 😬

I believe the reciprocity clause in Section 10.4.6 in the Takahashi Global Sales & Purchase Agreement specifies just this eventuality 

[Ted Mickle]

I've ordered a Takahashi Mewlon 210 and am enjoying your evaluation of the 210 and 250.  How did you get binoviewers to work with the 210 - using the native focuser, or using the FeatherTouch & Adapter that you mentioned?

[HizerKite]

Hi and sorry to revive an old thread but am really struggling and may have to ditch my mewlon and buy a new one as cannot, get it working well.

I'm trying to image Jupiter but can't get it sharp (see attached photo showing one of its moons and the best I could get it focused).

 

I'm following the instructions for collimation using a piece of  card but it doens't help as shows the vanes (4 of them) to be perfectly aligned and I can't  see any issue with them.

(see 2nd photo) excuse the quality as is taken on my phone

 

Really appreciate any help - I can't star collimate currently as there is no clear sky here for ages.

 

 

Edited October 18, 2023 by HizerKite

[JeremyS]

2 hours ago, HizerKite said:

Hi and sorry to revive an old thread but am really struggling and may have to ditch my mewlon and buy a new one as cannot, get it working well.

I'm trying to image Jupiter but can't get it sharp (see attached photo showing one of its moons and the best I could get it focused).

 

I'm following the instructions for collimation using a piece of  card but it doens't help as shows the vanes (4 of them) to be perfectly aligned and I can't  see any issue with them.

(see 2nd photo) excuse the quality as is taken on my phone

 

Really appreciate any help - I can't star collimate currently as there is no clear sky here for ages.

 

 

You need to wait until it is clear and star collimate.

These are the best guides I’ve found for my M210:

Post 11: https://www.cloudynights.com/topic/283204-mewlon-210-finally-arrived/

Post 2: https://www.cloudynights.com/topic/354729-best-ever-collimation-video/?p=4548838

[dweller25]

4 hours ago, HizerKite said:

Hi and sorry to revive an old thread but am really struggling and may have to ditch my mewlon and buy a new one as cannot, get it working well.

I'm trying to image Jupiter but can't get it sharp (see attached photo showing one of its moons and the best I could get it focused).

 

I'm following the instructions for collimation using a piece of  card but it doens't help as shows the vanes (4 of them) to be perfectly aligned and I can't  see any issue with them.

(see 2nd photo) excuse the quality as is taken on my phone

 

Really appreciate any help - I can't star collimate currently as there is no clear sky here for ages.

 

 

I also use the “hall of mirrors” procedure during the day to collimate my Mewlon, I find it’s good for 95% collimation, with SLIGHT tweaks being needed at x300 on a perfectly focussed star.

BUT - the mirrors must be fully cooled first - I use active cooling.

First I take off the front and rear caps, then rest a USB powered 50mm PC fan on the front spider for an hour - it works nicely.

Your “hall of mirrors” looks close 👍

Edited October 18, 2023 by dweller25

[dweller25]

@HizerKite

just noticed a slight collimation offset - see the two spider vanes I have highlighted in red below.

It may be worth checking the length of those two vanes - although it will not stop you getting perfect optical collimation.
 

Although it could also be an alignment issue with your camera position.

[globular]

Sorry to butt in momentarily but, for my future reference, how well does a Mewlon hold it's collimation once you get it right?  If it's just on and off a mount and into and out of the house should it stay 'forever'?  Or do they just naturally lose it over time - no matter how carefully it's handled?
Many thanks 

Edited October 18, 2023 by globular

[dweller25]

8 minutes ago, globular said:

Sorry to butt in momentarily but, for my future reference, how well does a Mewlon hold it's collimation once you get it right?  If it's just on and off a mount and into and out of the house should it stay 'forever'?  Or do they just naturally lose it over time - no matter how carefully it's handled?
Many thanks 

I decided to add a RACI finder to my Mewlon a few years ago necessitating back plate removal. So it needed a slight tweak when I put it all back together. It has held perfect collimation ever since after a lot of “in’s and out’s”

An American astronomer - Ed Ting found his Mewlon would not hold collimation but I strongly suspect the locking collar for the primary just needed snugging up. In my opinion they are very solidly made scopes.

[JeremyS]

4 hours ago, globular said:

Sorry to butt in momentarily but, for my future reference, how well does a Mewlon hold it's collimation once you get it right?  If it's just on and off a mount and into and out of the house should it stay 'forever'?  Or do they just naturally lose it over time - no matter how carefully it's handled?
Many thanks 

They hold it VERY well.

[globular]

4 hours ago, dweller25 said:

It has held perfect collimation ever since after a lot of “in’s and out’s”

17 minutes ago, JeremyS said:

They hold it VERY well.

Thanks both.
I'm not scared of collimating (ok, I am a bit scared) but I'd rather spend the few opportunities I get to observe observing rather than fettling.
Sounds like the Mewlon ticks that box.

[JeremyS]

18 minutes ago, globular said:

Thanks both.
I'm not scared of collimating (ok, I am a bit scared) but I'd rather spend the few opportunities I get to observe observing rather than fettling.
Sounds like the Mewlon ticks that box.

No harder than collimating an SCT.