Any SCT's/Mak's comparable to the Tak Mewlon's?

[mbaddah]

After having a look through Chris's beautiful Mewlon-210 few nights ago and having the best views of 47 tuc/M42/ etc... I was wondering if there were any Cassegrains, Mak's etc... which would be comparable (ofcourse not exact) to the Mewlons in terms of contrast (the Mewlon was velvet-black) and image quality (the 8" performed like a 12" dob!).

I never realised how bad the contrast is in my LB scope until I looked through Chris's Tak, I'll never look at my dob in the same way again (thanks Chris :sadeyes:).

[issdaol]

Hi,

I have personally used a friends Tak Mewlon 250 and Tak Mewlon 300 and the visuals have been the best I have seen so far. I am saving up for a future Mewlon 300 :-)

I have not used a large aperture (6inch or above) APO or Mak so cannot compare to them but I have used both Celetron and Meade SCT's up to 11inch and 12inch.

My current Celestron CPC1100 is good provides some impressive views but I have to say that both the Mewlons were better visually and far superior engineering/build finish.


Cheers

[Waxing_Gibbous]

I, unfortunately have also spent a night with a Mewlon. Its pretty easy to get spoiled for anything else. :(

A few years ago I was at the Texas Star Party, and had some time with an Intes 8" Mak. It was pretty speccy, but from memory, not quite up there with the M210. The only scope that I remember as matching or even exceeding it was an 8" Portaball with Zambuto optics.
But they're about twice the price of a Mewlon.
There are certainly no massed-produced cats/reflectors that compare.

If I was going to start again. I'd go with an M210 and an NP101 or LOMO/LZOS 4-4.5"

[casstony]

Thierry Legault has used Takahashi SCT and Mewlons and now uses a Meade 12" SCT according to his website. The link shows photo's from Tak 9" sct and Meade 12" sct.

http://www.astrosurf.com/legault/lunar.html

[mbaddah]

I think i'm going to have to do the same and start saving up for a Mewlon as well, maybe a Mewlon 250/300 though :)

Ive heard the following which use DK design also provide excellent views (and are just as expensive if not more):

Planewave
Parallax
Royce
Orion
Lazarotti

Any experience with the above from anyone?

[mbaddah]

On a side note I've just stumbled across an 8-inch Saxon Maksutov been sold here in Australia. I would assume this would be the closest to a Mewlon-210 out of all the mass-produced scopes?

http://www.astronomyalive.com.au/reflecting-telescopes/maksutov-cassegrain-telescope/saxon-maksutov-8-inch-reflecting-telescope-system.html
http://www.myastroshop.com.au/products/details.asp?id=MAS-065E
http://www.sirius-optics.com.au/saxon_mak.htm

[gregbradley]

I assume you mean the comparison for visual only?

I haven't seen any quality images from Mewlons. They are high focal length and smallish central obstruction scopes.

Meade ACFs though do produce a lot of good images and you'd get more aperture for your dollar if imaging was your game.

Planewave make corrected Dall Kirkhams (Mewlons are Dall Kirkhams) and are imaging /visual instruments with lots of happy owners.
Orion Optics UK also make a corrected Dall Kirkham and are about to produce an 8 inch one at F6.8. That would be similar to Mewlon 210 but shorter focal length. They don't have many examples out in the field yet but seem to be capable of producing a high quality product that on paper appears slightly superior to Planewave (but slow production). Ceravolo astrograph is also corrected Dall Kirkham (it seems to be all the rage in telescope design these days).

If visual only I imagine the Mewlon would be the one to beat. If imaging then the Planewave (big dollars) or the Meade ACF for bang for your buck.

Greg.

[issdaol]

I was recently talking to Claude regarding my options for the Tak Mewlon 300 and apparently the next release from Tak is also corrected versions of the Mewlons :-)

Apparently there is a retrofit option for older versions as well.

For me the decision to go with the Mewlon was based on the visuals I experienced and the engineering of the units combined with excelent advice and support from Claude in South Australia.

Cheers

[Wavytone]

Lack of contrast is frequently a problem in poorly constructed Newtonians.

Larger Maks on the market currently include:
- Saxon 8" f/12 Saxon,
- Skywatcher 180mm f/15 (I have one) from Andrews or Bintel,
- Questar's "Astro 7" or "Classic 7" (the Astro version is the better IMHO)
- the Meade 7" LX200, if you can find one secondhand.
- INTES MICRO - many to choose from.
- Cheap chinese 8" from Bosma, quality unknown.
- Orion UK have several 8" - 12".

Of the larger maks, ALL tend to suffer from tube currents and some form forced of ventilation is needed.

The Questar ones are far the best optically with consistently perfect diffraction disks, however there is a big premium to be paid for these; the benefit is you have a scope that performs as well as a 7" APO.

Second to Questar are INTES MICRO - consistently good quality optics and built like a russian tank.

The Skywatcher 180mm that I have is cheap rubbish - ie not great optically - it's resolution is barely better than my 4" refractor and it will not produce a distinct Airy disk. The orange C8 I had long ago was no better.

As for the rest... I suspect you take your chances.

Then you can consider of the Meade/Celestron SCT's in the range 8" - 11".

IMHO its a toss up between a Questar Astro 7, Intes Micro or a Meade 10" ACF. If cost is irrelevant, the Questar is exquisite and a lot more convenient but if you want the biggest bang per buck and the largest SCT that one person can reasonably set up, the Meade 10" ACF is the go.

[AlexN]

From everything I've read, the Intes Micro Maks are amongst the best mak's on the market, I'll give you a better description when my Intes M703 arrives later this week, but I've read may reviews that state for contrast and sharpness the Intes 7" Mak's rival Astrophysics 5"~6" APO's..

Maybe one day Dennis S. and I could get the his Mewlon 180 (180 F/12.5) side by side with my M703 (180mm F/10) and do a comparison...

[toc]

As an aside, this scope is currently in the for sale section :) Ive read very little about it though.

[toc]

There is also the TAL 200/300K scopes - they are a Klevtsov design though. (similar to the Vixen VC200 I think)

[mbaddah]

Thanks guys for all your informative posts. There's a few recommendations there for a Meade ACF, I would assume been an SCT it would be the least constrasty in comparison to the Mak or even a Newt due to the large secondary obstruction?

I thought the Mewlon was designed for lunar/planetary photography as well?

As a side note and something that had just struck me, how would a 16" dob with an aperture mask (say 6"?) fair against these scopes in views? I would assume the 6" is enough to still keep the moon and planets bright at a ratio of ~f/10?

[AlexN]

I have seen Jupiter through a 16" newt with a 6" off axis aperture mask... The view was pretty amazing, however the contrast difference was minimal compared to the newt without the mask, and the image was HEAPS brighter at full 16" aperture.

You're right, an SCT with a 40% CO will show less contrast than a mak with 20% CO or a newt with around 20% To be honest, I don't see the need for an ACF OTA with planetary imaging/viewing in mind... ACF only really makes a difference if you're using really wide EP's or imaging with relatively large imaging sensors for deep sky photography. For planetary you're only using the area of the mirror that is dead on axis, and therefor ACF won't make a difference. So if you could get the Celestron equivalent size SCT cheaper than the Meade ACF, the results will be similar..

I've owned a Celestron 11" SCT, and planetary views were amazing, as were lunar views... I never did much planetary or lunar imaging with it, however if you look around the net at the best planetary images being taken with SCT scopes, its almost all Celestrons... Paul Haese with his C14, Damien Peach with a C14 and his earlier work with a C9.25, Christopher Go with is C11...

I love the Celestron SCT's... Would have another C11 or a C9.25 today if I could afford it...

[toc]

I love my C8 to death as well - especially since I got it for the princely sum of 450 USD. :lol: (a few years ago now)

I hate what the company and distributors are doing to the pricing here though.

[Satchmo]

You can use an elliptical mask on a 16" to give a bit more light, say 6" on the short axis and 9" on the long axis.

Comparing a premium 8" F12 scope to a low cost 12" 0r 16" F4.5 is a bit like apples and oranges.

Cassegrains are often better baffled than truss dobs, and Newts if they are not perfectly collimated coma will smear the on axis image to worse than 1/4 wave . Id they have quality smooth optics ,clean coatings and are well baffled there should be no differnce in the contrast at equivelent magnifications.

The best way to make a fair comparison between a 12" F5 LB and the 8" Tak Mewlon would be to mask the 12" down to 8" ( the central obstructions will still be about the same ) , make sure the tube is shrouded and use the _same_ magnification in both scopes.

The darker sky background in smaller scopes , for a given eyepiece often gives the impression of contrast , compared to wider exit pupils, which also allow aberrations and inhomogeneities in the observers eye more apparent.

Dall Kirham scopes share design with Newts in that they have one aspheric mirror and spherical secondary ( in the Newt the secondary shere is of infinite radius ). The coma is twice that of a Newt of equivelent focal ratio, but most DK's are fairly slow less than F12.

[mbaddah]

Hi Mark,



Sounds interesting will have to give it a try.




So a dob with premium optics can equal in contrast that of a Mak and Refractor? If so i'd be disappointed knowing I just ordered the GSO mirror and not a Suchting mirror :( :D



If only I had the $$$ to do such a comparison :lol:

[Waxing_Gibbous]

I think the main appeal of the Mewlons and Intes Maks is that they "punch above their weight". By a long way!
The images, visually anyway, have more snap, more contrast, are cleaner in these scopes than in larger, mass-market SCTs or Newts.
If even 50% of your time is going to be spent observing rather than imaging, I think you'd be better off saving for a Mewlon or IM Mak (can't speak for the TALs).
Some rate the cheaper Maks (Saxon/Orion/Skywatcher -same scopes BTW), and while you more often than not get a good one, they have nowhere near the QC that smaller outfits do and the subsequent number of 'duff-to-delightful' examples is much higher.

There is also the matter of "accessability" to consider. A big (9.25"+) SCT or Newt is a lot of scope to lug around the garden. Even with a 'Scopebuggy' or similar wheeled carrier, these are big beasts with a lot of inertia. Some owners don't even notice it. Living on a farm, I lug around enough heavy stuff during the day. I can live without it at night!

Both Tak and Intes produce a fair number of these scopes,they're not rare, the waiting list is days or weeks rather than months or years. But see how many you can find used as opposed to "garden variety" SCTs.
Very few people want to part with them. Those that do are usually trading up to a bigger Mewlon or MK. :)

I reckon half the fun of this pastime is acquiring gear. Half the fun of that is arguing about what gear to acqire (IMO). But if you want to get the best for your buck from the outset, then the Mewlons or the IMs are impossible to beat.

"Good Scope"
Peter

[AlexN]

Im hanging out for clear skies to give my Intes Micro scope a fly... Its sitting on the test bench at the moment all collimated and ready to go! :)

[Omaroo]

Same here with the Mewlon Alex. Apart from that one night out - I haven't seen the moon with it yet, which is primarily why I bought it. Arghh! Damn weather...:(

[DavidTrap]

Looking out my back window, I don't like your chances tonight Alex... I just hope the weather clears up by the time my new toys arrive...

DT

[Omaroo]

Have you had the 102 out yet David?

[AlexN]

Yep - Weather here is not going to play nicely tonight thats for sure... We might see an opening over the weekend... though I'm not going to hold my breath... First light for the M703 will be the moon, followed by Saturn.. Hopefully new moon weekend will see it pointed at M83 with the ST8300 stuck up its butt end! :)

Alex.

[Paul Haese]

I got to say if I could afford it I would go for a 13" intes Mak for my planetary imaging. The light cone is very nice for planetary imaging. The Tak mewlon 300 is good but not big enough for serious aperture needs on the planets. The cost is also very prohibitive too. A Tak 300 mewlon is a beautiful scope and for visual use the views would be equal to any refractor you could normally afford.

For imaging well the humble SCT does a fine job. For now I will be sticking to what works for me and is cheapest to work with right now. If you can afford the mewlon and want it buy it for the visual use alone then do so.

[AlexN]

I drool at the idea of a 13" IM Mak!! My 7" is a far cry from 13", however it should be ok.. My cheapy skywatcher 8" newt provided good images of Jupiter, if a cheap 8" newt can do it, a top class 7" mak can too.. :) (I hope! :D )

[Waxing_Gibbous]

If I were you two, I'd be using them for advanced birdwatching or spying on people.
Seems criminal to have 'em sitting there. Might just as well send them to me!:D

[Satchmo]

A Dall kirkham Cass ( ie Tak Mewlon) is a reflecting telescope with two aluminised mirrors like a Newtonian. If full attention is payed to the issues of full light baffling ,smooth accurate optics , minimised central obstruction and high quality coatings, then there is no intrinsic reason for any contrast difference between the two types . You will not find all these features optimised in a low cost mass produced dob. I don't know what a Tak Mewlon costs but i would guess that all these features have been played close attention to :)

Refractor objectives scatter less light than aluminised surfaces , and are easier to baffle properly, but are limited in aperture. Maks are hybrids of which I've seen some really lousy and some really excellent examples of.

[AlexN]

I looked at a building or two during my initial test of the M703 Peter.. They were 25km away, so I figure this isnt exactly spying on people, but its been looked through!

[DavidTrap]

Not yet Chris - I tried to put it on a rickety part aluminium, part plastic camera tripod, but the plastic head couldn't hold position to look at anything for more than about 2 seconds!!! I decided to give up before I damaged something.

However, a request for funding was approved by the Minister for War & Finance and a mount should be here in the near future.

Regards
David T

[gregbradley]

Sounds like a nice option.

Retrofitting a corrector may not be enough for imaging as the secondary mirror size has to be enough to create a big enough imaging circle that is fully corrected. Then again Tak are awesome as imaging experts so I am sure they will come up with the goods.

Orion Optics UK though already make corrected Dall Krikhams with carbon fibre tubes, with triplet correctors, with fan controls, with design from scratch to be a great imaging scope as well as great visually things Mewlons don't have as standard.

Planewave also makes a 12.5 inch corrected Dall Kirkham for US$9995 which has carbon fibre tube, heavy duty focuser, 52mm corrected imaging circle, lightish weight, lots of fabulous images on the net and about half the price for the Mewlon 300. So the Tak scope is hard to justify when it doesn't have a carbon fibre tube (extra upgrade, which means focus will go off over temperature shifts to some degree as well as heavier), no fans (means thermal layers on mirrors unhandled and tube currents more likely) no corrector currently means no good for imaging, Mewlon no doubt is very heavy placing a strain on the mount so you may need a heavier duty mount.

Tak's Mewlons are really yesterday's design and were great at the time but the market has moved on and now they are overpriced, heavy and lack the versatility of the modern corrected Dall Kirkham.

The Mewlon 210 etc is still unique though as corrected Dall Kirkhams are usually 12.5 inches up. Orion Optics UK are planning an 8 inch but not yet.

Greg

[mbaddah]

Looks like there will be some clear weather for you guys to test out some of your rigs there :D If so please report how it goes :)

[Satchmo]

Can anyone enlighten me as to the cost of a Tak Mewlon 200mm in Australia ?

[Omaroo]

$4,625 incl. finder Mark.

Gee... that's harsh - "Tak's Mewlons are really yesterday's design and were great at the time but the market has moved on and now they are overpriced, heavy and lack the versatility of the modern corrected Dall Kirkham."

I'm pretty happy with mine, I can tell you! :)

[AlexN]

I'd agree with Chris on that... The Mewlons are beautiful, and for their designed niche, they are brilliant scopes. Sure, you can't wack a 52mm square CCD in the rear of it and expect a flat field, but why would you want to? its a scope with lunar/planetary work in mind... and for that purpose, there are really 3 optical designs that stand out. Newtonians, Dall Kirkhams and Mak Casses...

One could argue that a corrected RC is a better optical system than an uncorrected Dall Kirkham. However take a 12" RC and pit it against a Mewlon 300 for either visual or photographic planetary work, I'd have my money on the mewlon...

[Satchmo]

Yes , the more spherical surfaces the better for a smoother wavefront, which gives the DK an edge over RC's on-axis. The Dall Kirkham is similar to a Newt in having one aspheric and one spherical surface involved. Coma on an an F12 is the same as an F6 Newtonian ( which is minimal ) .

I think Greg's comment related to teh DK uncorrected being redundant as a deep sky astrograph. I don't think they would ever have been used for that purpose due to slow speed. That being said there are plenty of nice 2" 40mm 70 degree eyepieces around that would deliver a 3.3mm pupil at F12 , so would still be very nice for medium field deep sky.