5" apo Vs Mewlon 180

[Benjamin B]

Hi all!

I have two scopes in mind and it´s quite difficult to decide which one to but, specially since I have never used or seen one live.

I have read about the Chinese 127 ED apo and it sure looks great. But, will it be a good scope?

I have also been looking at the Mewlon 180. The price difference is quite large, but Takahashi is always Takahashi.

The mount I am going to use is a Losmandy G11. Will the 127 ED apo tube rings fit?

[Starkler]

What do you want to do with it?

Visual? ap ?

[Benjamin B]

Visual and moon/sun photography. No CCD.

[Ian Robinson]

Got the money , go for the Tak Mewlon 180 .

Seems to me - it's a no brainer.

[Dennis]

Takahashi have discontinued the Mewlon 180, so I assume you will be looking for a used one?

Cheers

Dennis

[Benjamin B]

Yes, I use one.

[gregbradley]

Hi,

Firstly the term "APO" gets bandied around by scope manufacturers and has become degraded as a term.

It actually means all colours come to focus at the same or extremely closely the same point.

A Chinese ED doublet will not be able to comply with that definition. It will be sharp and a pleasant view but it will have some colour on bright objects to one degree or another.

There has been a lot of discussion about this point over the years in refractor Yahoo groups.

Generally the scale for refractors is something like this:

1. Astrophysics , TEC. Takahashi triplet (TOA or TSA series) refractors - true APOs
2. TMB Stellarvue triplets -true APOs
3. Takahashi fluorite doublets
4. Other ED doublets a fair drop down from #3.
5. Achromats.

So a Chinese ED doublet should really be called a semi-APO but of course that does not make good marketing. Not to say it wouldn't be a pleasing scope as 127mm aperture for a refractor is getting very useable.

A Mewlon though has no lens elements so there is no false colour, and the spot size is low near the centre and weakens as it goes off centre.

Below a Mewlon 250 the focus is by moving the primary mirror which is fine for visual but probably a pain for imaging (mirror shift).

I have had several Tak scopes and a mount and they were all fabulous scopes and very haveable. Whereas a Chinese scope is usually great value but a bit rough around the edges.

Greg.

[Alchemy]

there are currently a few images in the deep sky version with the Chineese 127 ...... of note is the blue halos around the brighter stars, in this case the APO term really should not be used, and as greg says somewhat diminishes the term. Having said that, at 127mm that you can buy for 1200 or so dollars, the william optics 132 is 5000 and the Televue 127 is 10000 so its probably ok value for what you pay.

[Kal]

Isn't the Chinese 127 apo the OP is referring to an FCD1 (FPL51) triplet?

[Alchemy]

no idea the one i was referring to is this http://www.iceinspace.com.au/forum/showthread.php?t=33885
it appears to be the one a few have imported lately (note- the scope used is listed as 127mm APO), theres plenty of detail in the shot but the stars exhibit the blue halo i refferred to.

[gregbradley]

There is a bit of competition in this area.

There is a 130mm triplet I saw at Bintel that would most likely be better as it is a triplet. There are also a number of used Tak FS128 that have been selling rather cheaply on Astromart. There is also the TMB130 SS that are also good value.

But as you point out they are not AUD$1200 more like about AUD$3500 including shipping and GST form Astromart.

If you want to do visual then an Orion Optics UK Mak Cassegrain or Mewlon 210 would be the go.

Greg.

[JohnH]

Humph! Call it what you like this scope is a performer - the blue halos only happen if you do not get the focus spot on. An example image here:

http://www.iceinspace.com.au/forum/attachment_browse.php?a=44437

Or do a forum search for 127 APO and see what others are doing with this scope. I liked it so much I sold my Vixen VC200L and kept the 127 ED.

[marki]

Nice pic John. They certainly seem to be well corrected for colour if focused properly. They are a triplet aren't they?

Ciao Mark

[Phil]

I have to agree with John I have the the 127mm to and love it. This scope will be staying in the observatory next to the NP101mm. Like John says it is a performer.
Phil

[Benjamin B]

Thanks all! I think i will go for this scope. :D I have only heard good thinks about this scope, so I will order one.

[JohnH]

Yup it is an air spaced triplet design.

[toyos]

Even though I'm not deeply impressed by the colour correction of this 127 semi APO, but I prefer a refractor to a comparably-sized reflector of any kind. Can't match the contrast, sharpness & image crispness of a refractor plus I'm not a big fan of diffraction spikes.

It's actually quite a pain getting the focus on that 127mm ABSOLUTELY spot on to get rid of the false colour, and the focuser itself isn't very smooth. Even the el-cheapo GSO Crayford 1:10 works better.

I might sell my 127mm if you're interested since I bought it last month just out of curiosity.

[h0ughy]

i have fixed this problem by using a JMI crayford focuser with robofocus unit;) - it just slips into the existing 2"

[Benjamin B]

To be honest I take it with a grain of salt when I read people that says they can see some color on bright objects. I can see that too with my TMB super apo and as well with my Takahashi. BUT this has nothing to do with the scope! Bad seeing, eyepiece, diagonal and a star/moon that is low in the sky will show some color. Color will also be seen in AP, WO, or any other expensive telescope when other factors are encounted.
The blue hallows in pictures can also be an effect of internal effects of the camera. Seen that with AP, Takahashi, TMB and other telescope. One have to be very sure that the scope is the problem. And the telescope is an apo with 3 elements/triplet objective, not a semi apo. If this is a semi apo my Takahashi and TMB super apo is also a semi apo. This is my opinion.
The lences are from Japan, not china. I have talked to people that bought this scope and have not seen any color what so ever.
I will not take any CCD or images of DSO with this scope, just the moon and sun.
I think it will be perfect for me.
About the focuser, well, I have read that the Takahashi focuser is not good! Well, in my opinion, I like the Takahashi focuser over my FT on my TMB.
The focuser can be fixed on the 127 apo if there is really any problem.
I will let you now all when my scope arrives. Thanks all!

[Kal]

The raw glass used as the ED element in the lens is FCD1 glass from a factory in Japan, but the lenses themselves are manufactured in China.

[IanL]

I have the Mewlon 180 and some others on the site have Mewlons of different flavours as well.
Getting collimation can be a bit of a struggle but once it is collimated its one of the best scopes I have looked through. I have never saw festoons through a scope with my eye and it was the first scope I could really see the GRS with my eye.

For planetary imaging it does a great job. For the scope itself to cool down takes no time at all and dew so far for me has never been a problem. On low end 5” inch refractors I have no doubt that mewlon would knock the socks off most of them.
I have attached a photo of a pic i took of jupiter after 2 months of imaging with it
Ian

[Zuts]

I will probably cop a lot of flack for saying this but, the fact that it is a 3 element apo is irrelevant. I had the Meade 5000 ED 80, which i sold. It was also a 3 element apo. Most reviews I have read say it is a damn good scope. I agree, for the price. It also took some nice photo's, however it was no match at all, not even close, for my TV85, a two element ED type scope. Quite frankly I dont see how it is possible for the 127mm to be any different when compared to say a Tak FSQ or Mewlon. Sure it's a nice scope for the price but i think that qualification says it all.

my 2 cents
Paul

[Benjamin B]

OK, One thing is Imaging and the other is visual. I don´t do Imaging and I will not do that with this scope, maybe on the moon and sun, but manly visual. So, if we forget imaging, how much of difference are we talking about here? I will not use this telescope in super dark places, only close to my home.
I have seen images taken with a WO telescope, like the WO 66mm and with a FSQ, and I personaly could not see any difference. So, for me I don´t like to pay saveral times more for a scope that is on the paper better but with the human eye one can hardly see any fifference. For me I don´t see the point. I want to enyo the night sky with a telescope. :rofl:

[toyos]

I have a 4-element/quadruplet Petzval 6" refractor, so you call this a super 'apo' then? :lol::rofl:I think the term 'APO' has now been loosely used by some manufacturers to market their inferior products.

I know the difference between chromatic aberration from the scope or from other 'factors'. I tested the scope on several occasions on various objects across the sky in and out of focus using a range of ep's including Naglers and an Ethos. The dielectric mirror from my diagonal does not cause false colours.

Anyway, compare it properly yourself against a triplet Tak in and out of focus when you get it. Even my 9-year old niece can tell the difference in colour correction. But I'll still take this over the Mewlon 180. Since you've already convinced yourself with your own reasoning, go for it, as long as you're happy with it.




The WO is only 66mm and the FSQ is 106mm, it's easier & cheaper to make well-corrected optics with only 66mm. If you've done the comparisons based solely on other people's images, keep in mind that the results would also depend on their imaging & image processing skills.

[Zuts]

The Meade 5000 ED 80 had a quite curved field. With a very low power eyepiece the view was no good as it was too curved. At higher powers it was OK. It was a better imaging scope than a viewing scope. The TV85 is flat across the entire field with even a 35 mm panoptic.

The Meade ED80 is the baby brother of the 127. It may be better as it has a longer FL than the 80mm, i am not sure as i dont own one.

The Skywatcher ED 80's also suffer from this problem.

I would go for the Mewlon, but i wont suggest that to you because the scopes are not in the same leugue price wise, so not a fair comparison. Also the Mewlon is not a rich field scope by any stretch of the imagination, its what F9 or more? So again not possible to compare.


Cheers
Paul

[HAlfie]

this is my first post here, my english isn't perfect but I'll try to do my best to be understood ;-).



Hello Benjamin :hi:,

I have already viewed in a Takahashi FS128 (5") (which, I think, might has a better color correction than the meade 127mm) under excellent seeing conditions and I have owned a Mewlon 180 during approximately one year that I used for both visual/planetary imaging..
I'm gonna give you a few advice ;), I hope it will help.

Visual : a few years ago with 2 friends, we tried a face to face with the mewlon 180 and the fs128.
- On Saturn under very good seeing conditions (with same magnification and field), both tubes delivered sharp and very contrasted image. The image in the fs128 refractor appeared to be slightly less agitated (because of the closed tube) but the image delivered by the mewlon 180 appeared to be a bit, I quote : "less dimed" than the FS128. The person that I quoted just above had a personnal made dobson 24" and 40":scared:.
We made the same test with M42 and we went to the same conclusion.
--> Both tubes are very close in visual use. But if your observation place has often wind, you should tend to buy a closed tube that will provide you less agitated image. However, notice that the mewlon has 97% reflecting mirror and no menisc of other compared to maksutov-cassegrain or SC. My advice is that the mewlon ,180 can compete with the best 8" SC in visual and "high resolution" imaging.

Moon photography :
For webcam of DMK imaging, I strongly suggest you to go to the larger aperture. You'll get more light to the ccd or cmos chip, and you'll have better resolution.
Without a doubt, the mewlon will beat a 5" refractor in moon imaging due to its better separating power and better luminosity.

Sun photography :
Now, it depends if you're want to do close-up pictures of the sun or if you prefer do entire pictures of it.
On the first hand, you would have a 5" refractor wich would give you images with less shaking (and only under medium or poor seeing), but on the second hand, you'll loose resolution (or separation power, I don't know how to translate) for close up pictures (espacially under good seeing).

To conclude, the Mewlon 180 is not very heavy and is shorter than the refractor.
A 5" refractor is longer and might be heavier. If the mount that you mean to use if not enough solid, you'll be subject to vibrations during your observations and imaging. And vibrations are quickly exasperating !!
The mewlon got shifting, but twice less than a SC celestron or meade. The collimation hold out, the mechanical is serious build, you'll keep it a long time.

For example of mewlon 180 picture, here was my best image of Saturn in 2004 with a toucam pro 2 color Webcam and a klee 2.8x with extension tube (3.45x effective 7500mm focal length).
http://astrosurf.com/halfie/images_persos/mewlon_180/Saturne2_mewlon.jpg
A short avi of this night (divx coded):
http://astrosurf.com/halfie/images_persos/mewlon_180/Saturne.avi
Jupiter here :
http://astrosurf.com/halfie/images_persos/mewlon_180/jupiter5_big.jpg

If I were you, I would take the mewlon 180 :D.

[Benjamin B]

If I say it like this:D

I will buy me two scopes. One 5" Apo and one SCT like the C9,25/C11.

My plan is to use the 127mm apo for visual and of course shoot the moon with, but I do plan to use it for public.
I just want to know if this chines telescope have what I am looking for.
Excellent visual on moon and planets. Quick cool down.
If I am going for CCD work one day I will use my TMB telescope. But right now I´m just interested in visual. But I do not want to buy something that is of bad quality and bad mecanics. I have read several people around the world on different forums that have bought this scope and are amazed about the quality of it. But when i hear you guys telling me that it is not good, I hecitat of course.
I will mount it on my G11 so mount is stable enouth for heavy scopes.

So, tell me. Is this scope from China going to be a good shoice, or shall I go for something ealse?

One more question, can I mount it on my Losmandy G11?

[gregbradley]

One way to work it out is to decide on what image scale you want to have.

Image scale is the size of the object viewed through the scope.

These 2 scopes would have completely different image scales using the same eyepiece. The refractor would be widefield and the Mewlon close up.

So if you want detail on the moon and planets you need a long focal length. This then is the Mewlon.

If you want widefield you get a refractor.

A widefield refractor may not be the best scope for viewing the planets. They will be too small unless you use really short length eyepieces or barlows and then you are putting more glass in front of your view which is not ideal.

So for planets, moon and deep space objects the Mewlon makes sense.

For widefield views, sharp and contrasty then a refractor is the thing to use.

This is one reason Schmidt Cassegrain are so popular as they give a great visual view and are compact.

Greg.

[Stephan]

I don't know what TMB or Takahashi you are refering to, but there is a good chance that the colour you see in those scopes really is cromatic abaration especially if you refering to a Takahashi FS128 or FS152 (even the FS102 is not 100% colour free). Almost every review will confirm that, just Google it!

Regarding the TMB's there is the problem that they sold telescopes with so many different lenses from different manufactures (of widely varying quality) that it is difficult to determine how good your TMB should be. To my knowledge the only TMB's that are completly cromatic aberation free are the fluorite triplets sold in the mid 90's. You will come to the same conclusion if you read the various reviews of experienced TMB-scope users (especially if you read between the lines).

The reports that I find in the Internet about the Chinese 127 Triplet seem to confirm what has been said in this thread:

- good value for many
- not a true APO
- a bit rough around the edges

All at all, I think you will be happy with the Chinese 127 Triplet if you don't expect it to be perfect !

CS

Stephan