Why are mak-newts not popular?

[mldee]

I'm just trying to improve my knowledge while displaying my ignorance:D

It seems to me that for both viewing and imagery, a 10" Mak Newt with Baader MDCC would be a pretty good coma-free and diffraction-spike free performer, and one heck of a fast light bucket.

Yes, more expensive than a simple equivalent-size dob, but a better performer than many of the other more upscale scopes we seem to lust for, (yes, you and me, AlexN).

Sure, much bigger than an RC or even SCT, but still easy to sit on an EQ6 and no more difficult for viewing than a standard 10" newt dob which many IIS folks possess.

It just seems like best bang for the buck, to hang either a good EP or CCD on, but not popular. Can the more knowledgeable please enlighten me?

Signed, concerned gadget freak.

[ausastronomer]

Hi Mike,

The Mak Newt design is a good one, particularly in smaller apertures. The difficulty with the design comes about because of the Maksutov Corrector plate at the front of the telescope. It is very steeply curved and very thick, particularly at the edges. This makes the corrector progressively more difficult to make, as the aperture gets larger. Further, as the corrector gets larger, cooling issues get worse, particularly having regard to the fact that the scope is a closed tube design. Generally Mak Newts perform at the best around the 6" aperture size. The largest I know of that is readily available is the Intes Micro MN 86 which is an 8"/F6. The Intes MN 61 (not the same company as Intes Micro, but both Russian) was also sold as the "Orion Argonaut". It is a 6"/F6 Mak Newt and one of the best 6" instruments you will find, of any manufacture or design.

Cheers,
John B

[mldee]

Thanks John, point taken,

The reason I got caught up in this was chancing on an article for the Meade LX75 10" SN-10 Mak Newt. I suspect this is no longer in production, various reasons are floating around on the web.

While 10" may be stretching the limit for a mass-produced corrector lens, it would be a good performer, which may offset the additional production costs, especially compared to, say, a 10" RC or SCT, which are readily available.

I'm also a little surprised that someone hasn't yet come up with some really creative air cooling systems for closed-tube OTA's to offset that problem.

Don't worry about me, I suspect I'm also a frustrated inventor:P

[ausastronomer]

Hi Mike,

The Meade SN-10 is a Schmidt Newtonian, not a Maksutov Newtonian. The curves in the Schmidt Corrector are much easier to generate and it is a lot thinner than a corresponding aperture Makstov Corrector. This is evidenced by the fact that Meade Schmidt Cassegrains are available in apertures up to 16". These use the same corrector as would be used in a 16" Schmidt Newtonian.

Cheers,
John B

[ausastronomer]

They have. Roland Christen of Astrophysics produced a very small number of 10"/F14.6 Maksutov Cassegrains about 8 years ago. These were outstanding telescopes incorporating a specially designed rear cell with special cooling fans and exhausts, to aid cooling. At US $10K or US $1K per inch of aperture, they weren't cheap.

Cheers,
John B

[marki]

Or you can just use these.

http://www.optcorp.com/ProductList.aspx?uid=105-766

They work ok and reduce cool down time by about half. Only problem being that it cannot be attached whilst you view or take pics. Some people have also used peltier cooling on large closed tube SCT's. Theres a thread in the ATM section some where.

Mark

[Paul Haese]

Actually I came up with a design for cooling a SCT, it would apply equally to a Mak Newt too. I adapted the idea from Bird who made one for his Newtonian.

See this link for cooling a C14 (http://paulhaese.net/peltierstoSCT.html)

I have also seen Mak Newts made up to 10" by Stellar Optics (http://www.stellaroptical.com/newt.htm)
The look pretty nice but cost a lot of money. A Mak Cass might be better still and Stellar make them too.

[pgc hunter]

I think the lack of popularity of Mak Newts is due to the following factors:

1. Price
2. More difficult to produce than conventional newtonians
3. Price
4. Conventional Newtonians are much cheaper to produce
5. Which again leads to price.
6. Price.

[gbeal]

Mak/Newts are available as big as your wallet will stretch. I had a 10" for a while, nice, but heavy and expensive.
The MN66 or MN76 are hard to beat as all rounders, but being heavier then similar newts they need a slightly beefier mount.
On another note I have recently acquired a 7" Maksutov Cassegrain, and am absolutely loving it. After being apprehensive about imaging at 1800mm focal length it is going well, and the images are coming out OK.
Gary

[mldee]

Thanks for the clarification John. This is the 'displaying the ignorance' part of things.:doh:I was under the impression that a Schmidt corrector would be about the same level of production difficulty as a Mak. Obviously not!

I also was dumb enough to think the Meade was a Mak Newt.

So let me ask the same question for a Schmidt Newt: Fitted with an MDCC, a 10" or even 12" Schmidt Newt would give good bang for the buck, but there's not that many around. Is it just that folks prefer the SCT, even though it's not as fast and presumably far more costly?

The background is that now, with USB Liveview + USB focussers, the inconvenience of a high focusser position is far less important, so a low-cost Dob-derived Schmidt Newtonian on EQ6 could be attractive, especially for imaging, with the occasional EP session.

Perhaps I'm just being pedantic, too:screwy:

[Starkler]

I understand the mak newt design to have 1/2 the coma of a traditional newt for a given f ratio.
Assuming the above to be correct, why wouldnt one just use a conventional newt with a mpcc, or isnt that 'exotic enough'? :whistle:

[Satchmo]

I think Mak Newts can be pretty well corrected for coma over a reasonable size field, but yes I don't see the fascination when you can by an equivelent Newt tube assembly for about 1/4 the price and just add an MpCC. I think the thermal issues of having that big hunk of glass in the BK7 menisuc corrector up front are not trivial too.

All that being said there is something appealing about a scope that has all spherical surfaces and no spider vanes.

Mark

[mldee]

Of course 'exotic' matters! These are boys' toys, but please also see my Schmidt Newt comments below, as I now understand Mak's are far more expensive.:D

It was just the 'elegant simplicity' of a low-cost, spiderless, diffraction-free, coma free, dust free, fast light bucket OTA that seemed attractive.

If it's not practical, so be it:nerd: