Opinion on Maks

[TheFacelessMen (Rob)]

Hi All,

Been thinking of a really good 6 or 8 inch Mak as a second scope.

Any opinions on quality of particular manufacturers? Who are considered better combined quality mechanical and quality optics manufacturers??

I also recently saw an add in the classifieds

http://www.iceinspace.com.au/forum/s...d.php?t=112465

It reads a bit like a dodgy second hand car sales add (apologies to the OP :-) ) once you get past all the redundant exotica, staggering, superlative, ultra amazing terms is this scope a reasonable scope?? Is $9000 around the right tpe of price one would expect to pay for a really good Mak?

Any advice/help appreciated

[MortonH]

The ad you mention is certainly for a very rare "ultra premium" scope. Is it worth $9k used? I can't say.

What I can say is that Intes Micro of Russia are regarded as one of the best makers of Maks in the world. One place in SA sells them, see the ad for "Takahashi Australia" on the side of IIS, or click here

http://www.astronomy-electronics-centre.com.au/

Apparently these are all made to order now so it can take a few weeks to get one. There are a few people on IIS with Intes Micro scopes. I had a 7" f/15 for a while but circumstances at the time prevented me from getting real use out of it and I sold it. Optics were very good. Should have kept it...

Cheers

Morton

[ausastronomer (John Bambury)]

I wouldn't be pulling the trigger too fast on that Quantum 8. I will post some more detailed information on the Quantum 8 tomorrow when I have more time.

Cheers
John B

[UniPol]

I recall that the Quantum 8 was manufactured by Optical Techniques Co. in the US. The "Telescope Bluebook" states :

"Optical Techniques Inc.

This company was started in 1977 by former executives of the Questar Corporation. Their sole purpose was to manufacture a Questar quality instrument without the accompanying Questar price. Their sole product, like Questar, was high quality Maksutov telescopes. The company did well for a few years, but was not able to sustain their product, and ceased production in 1982.

The Quantum series was introduced in 1978 and lasted until 1982. These telescopes were of very high optical and mechanical quality and are much sought after today. The Quantum 4 was a 4" f/15 optical system with a built-in flip mirror a-la Questar. This would allow the image to proceed through the telescope back to a camera or other accessories or divert the image through a 1 ¼" eyepiece holder. When diverted through the eyepiece holder, another knob could insert a barlow lens. The optical tube, with its 6x30 RA finder was placed on a single arm fork type mount with an electric clock drive and table top legs. Quantum 6 was the 6" f/15 version of the above telescope, but with 2" eyepieces a larger support arm and a 8x50 RA finder. The largest model of the line was the Quantum 8. This was an 8" f/15 optical tube with the 2" eyepiece back like the Quantum 6. It was made as an optical tube only. There very few of the 8" models made, and as a result they are very expensive."

Optical Techniques produced a catalogue in 1978 for their range however the Quantum 8 came later, see here http://geogdata.csun.edu/~voltaire/c...um/quantum.pdf

You would be hard pressed to go past the Russian Intes series of Maksutovs, maybe not the best finished scopes around but quality where it counts.

Jacob Apfelbaum (IIS member) was selling a Quantum 8 here on IIS some years ago, I don't know if he ever sold it, here is the link http://www.iceinspace.com.au/forum/s...t=quantum+sale

[Larryp (Laurie)]

Hi Steve,
I remember looking through Jack Apfelbaum's scope when he first bought it many years ago.

[Wavytone]

Rob,

These scopes are long focal-lenth and their primary role is high magnification views of planets, moon, double stars. They're not ideal for low power wide fields, if that is your thing. Short of buying an f/15 APO refractor of the same aperture (expensive, big and bulky), a good f/15 Maksutov is the next best thing. If you are thinking of one, you may have to re-think your eyepiece collection to suit a long-focal length scope.

With all the maks from 7" aperture and up, cool-down time will be an issue if the OTA is not ventilated. The usual symptom is that while cooling down the air inside settles into a laminar flow driven by the thermal gradient inside, and the result is a rather weird "spike" degrading star images. Either wait and hour or so for this to stop, or move the tube rapidly to break up this air current.

With respect to quality of Maks, there are:

1.Questar, well known for their various 3.5" and 7" models. The best of the best and set the benchmark for all. Questars are ostensibly perfect, optically outperforming just about anything of comparable aperture and mechanically they are works of art. If you own one you will probably keep it for life.

Questar have a range of mirror and corrector coatings designed to last a very long time, and in addition provide full service if you wish to have an older one refurbished.

b) Quantum. Started by some guys who left Questar, there were 4", 6" and 8" models. Direct competition to Questar at the time, they were optically excellent. However: These scopes are now 20-30 years old which means the mirror coatings won't be in great nick. In addition its not at all clear whether the correctors were antireflection coated, some of the photos imply they weren't which means theres a 15-20% light loss for starters. With poor mirror coatings, transmission could be as low as 50%. Need to consider whether you're buying a collectible museum-piece, or a scope that you will actually use regularly.

c) TEC. (Telescope Engineering Company). Makes big maks from time to time, optically these are superb but huge, heavy, expensive and really only suit an observatory.

d) A few odd-ball big maks are offered from time to time through APM in Germany, mostly using high quality russian optics, assembled to order. These are usually listed on Astromart - when available.

e) Dynamax. Another attempt to copy Questar, complete rubbish, steer clear.

f) Meade 7" f/15. The Meade 7" Maks are excellent optically and if you can find one, buy it. Only thing to note is that the ones in the fork mounts had a heavy iron weight in the back to balance the OTA in the fork, some of the de-forked ones have had this removed which also improved the cool-down time.

g) The russians: Intes / Alter / Intes-Micro / LOMO. The russians made excellent maksutov and maksutov-newtonian optics, various sizes from 6" to 12" and focal ratios f/8 to f/20, and you can still buy one of these. Excellent choice if you can handle the hassles of buying one, or pick one up secondhand.

h) Celestron. Made a few small maks from time to time, mainly spotting scopes.

i) Skywatcher. Cheap chinese clone, optically not in the same league as the russians or Questar, but mine is nonetheless a fine scope. 127, 150 and 180mm apertures. One aspect of my 180mm f/15 Skywatcher is that its about the smallest mak that has a proper 2" back for big eyepieces. If you have a chance to try a few and hand-pick one, I would because you could get a really good scope at a bargain price.

j) Saxon. Cheap chinese clones, 90, 125, 150 and 203mm apertures, optically OK.

k) Orion. Orion in the UK sold a few maks, up to 8", probably rebadged chinese clones.

l) Bosma. Cheap chinese clone.


A few oddball copies appear from time to time in smaller apertures but these are the main ones to watch for.

[dannat (Daniel)]

most mak's are a sealed tube & hence the mirror can remain in very good condition for a long time, a well kept celestron orange tube from the 70's can be still good today (unlike newts which are open to the air)
the thing the old mak's lack are th newer coatings on the corrector glass on the front -how much diff it makes is up to the observer.
To check prices goto the classifieds section of http://www.astromart.com
click search in the left hand column & type in quantum 8 or 6 -- keep in mind the quantum ota's go for lower than the equiv questar model (no mount)-so if you cant find any 8 sales check the questar 7 prices & work your way from there

[netwolf]

Some information here on the Russian Maks Intes, STF and Santel.

http://www.stellaroptical.com/cass.htm

[Steffen]

The pedigree of Russian optical design (or what's known of it) seems fascinating, I hope some day one of the main protagonists will write a memoir to fill in the gaps.

There appear to be several diverse continuing lines of Russian Mak designs. The Intes-Micro Maks are quite different from the original Intes Maks, whose designs seem to live on at Santel (though I have no way of knowing for sure).

Andrey Strakhov, the designer of my Intes MK-67, is now designing Super-APOs at Astreya (some of his designs were sold by WO under their FLT moniker). By all accounts those Astreya refractors are up there with the very best at a much more agreeable price.

Cheers
Steffen.

[Wavytone]

Steffen,

Regarding the pedigree, Sky & Telescope's "Gleanings Bulletin C" provides all the early history including D.D. Maksutovs original paper, John Gregory's design and a few others. These articles cover the theory behind a prime-focus Maksutov (essentially a Maksutov-Newtonian), the familiar Maksutov Cassegrain, and the theory for the sub-aperture corrector as used by Vixen and a few others. I have a copy, if interested. Scientific American's 3-volume set "Amateur Telescope Making" from the 1950's has a few chapters too, mainly on making the corrector. Interesting reading.

There are some texts that cover the maksutov design.

As the Mak uses spherical surfaces to a first approximation, the design is analytic and the fundamentals of the corrector can be solved algebraically, see for example http://www.cfht.hawaii.edu/~baril/Ma.../Maksutov.html
http://www.telescope-optics.net/maks...ctor_radii.htm
http://www.telescope-optics.net/maks..._telescope.htm
http://www.telescope-optics.net/Mak_spherical.htm
http://www.telescope-optics.net/MCT_off_axis.htm


After that, there are a few more variants such as the Field, van VenRooi, Rumak, Sigler and Rutten ones, which appear in ATM articles which appeared in Sky & Telescope as well as a few in a rather more serious journal "Applied Optics", for which you have to trawl the annual and 10 year indexes.

Of these the Rumak is perhaps the most interesting one as it was an attempt to produce a fast (f/8) design by separating the secondary from the corrector, although the central obstruction is of necessity quite large, though that won't matter to a camera.

The Questar, Meade and Skywatcher ones are basically the Gregory design.

[TheFacelessMen (Rob)]

Thanks for all the good tips and advice everyone. Much Appreciated. Look forward to seeing John B's review and maybe look closer at the Intes Micro's and other options

[ausastronomer (John Bambury)]

Hi Rob,

Well a couple of the other guys have already given you the previous history of Quantum Optics, being a breakaway from Questar in the late 1970's.

Unfortunately they only lasted 4 or 5 years, in production. The Quantum 8 was a scope they introduced towards the end of the company's life, as it approached death, with a view to boost flagging sales. Sadly, there were only about 8 of these produced and due to the company's pending demise, quality control on the Quantum 8's was bad and a couple of the Quantum 8's were lemons. The good news is that the Quantum 8 Jack Apfelbaum brought in to Australia (the one now for sale) is a good one. I looked through this at the South Pacific Star Party about 10 years ago.

However, that doesn't make it a purchaseable commodity for mine, unless you are looking at it as a collectors item or want the, "nostalgia" value.

We considered purchasing this telescope from Jack Apfelbaum to become part of our 3RF Australia scope arsenal for use at the Ozsky Star Safari, prior to the current owner buying it. However, we decided against the purchase as most of our US visitors and clients are after larger aperture scopes, more suited to DSO viewing. Further, we decided that if we did wish to purchase a large Maksutov, one of the new Russian Maks would be a better option, being cheaper and a better telescope due to the newer coatings and coating technologies.

That Quantum 8 would have been manufactured in 1981 or 1982, making it about 32 years old. There have been monumental changes in coating technology over the past 32 years and those 32 year old coatings would have had to deteriorate to some degree, reducing light gathering ability, compared to a new scope of equal aperture.

I posted this comparison in another thread last week showing the light loss comparisons due to the compounding effect of multiple optical surfaces. and the deterioration in coatings over time.

If we assume the reflectivity of each mirror in the Intes has dropped from 87% when new, to 80% at 20 yrs old; and we assume transmission on the corrector has dropped from say 97% to 94% after 20 years, the overall drop in light transmission drops from 73.4% when new, to 60.1% at 20 yrs of age, or a decrease of 18.1%.

Lets assume the Skywatcher with its newer technologies has 90% reflectivity on both mirrors and a corrector plate transmission of 98%. This gives an overall light transmission for the scope of 79.4%. This is a 6% increase over the Intes when it was new and a massive increase over the Intes with its aged coatings.

With that Quantum being 32 years old, it would only get worse than the scenario for the 20 year old Intes in the above comparison.

The quality of the Russian Maksutovs from Intes and Intes Micro is excellent. Here is a link to a test report on an Intes Micro M715 by Wolgang Rohr in Germany. This is a 7"/F15 Maksutov with a "system" strehl ratio of .985. It just doesn't get any better than this.

On the basis you can buy the Intes Micro M715 "deluxe" (7"/F15) for $4,225 and the Intes Micro M815 "deluxe" (8"/F15) for $6,175 you might want to seriously think about a Russian Mak. If you wish to use the scope for Deep Sky work and want a bit more versatility you might want to consider the F9 versions of these scopes (M709 and M809). Further if you didn't feel the need to buy the "deluxe" versions you save about another $1,000 per scope.

On the other hand if you want a scope that has some "collectability" to it then the Quantum 8 is a great scope, albeit with 32 year old coatings and coating technology.

Cheers,
John B

[TheFacelessMen (Rob)]

Hi John,

Thanks for the great overview. I seems like the new Intes would be a better option for my need.

Thanks for all the advice all