Are Mak Cass scopes good for visual use?

[gregbradley]

I have mainly used either SCTs or refractors in the past for visual.

I should try my CDK again.

But for a lighter setup how would you rate Mak Cass scopes and what brands and apertures would you recommend? I don't think I have even looked through one before.

Greg.

[Wavytone]

Depends what you want to observe and which mak you’re thinking of.

When Saturn is high in winter you’re welcome to have a look through my MK91, think you will be intrigued.

Sometimes I’m at the NSAS site at Terrey Hills or, if I can make it, Blackheath.

[gregbradley]

Hi Nick,

I don't know a lot about who makes Maks. TEC used to. Skywatcher/Saxon seems to have some. Meade had a small one on a goto. Intes Micro used to make them.

Mewlon isn't a Mak but seems in a similar category. Price is now a fair bit higher though.

Just general visual not specifically planets more like an SCT goto which is a jack of all trades visually.

I don't know a lot about them or which ones are good or best value.

Greg.

[Wavytone]

Well...There are several issues.

1. There are several mak variants:

- Maksutov Newtonians, mainly by Intes and Skywatcher; typically f/4 to f/8;
- DD Maksutov's original designs;
- The "Gregory Maksutov" cassgrain with an aluminised spot on the corrector, probably the most common type;
- the Rumak cassegrain, where the secondary mirror is separate from the corrector;
- sub-aperture mak cassegrains (Vixen and Takahashi).

2. The optical characteristics inherent in the design you are considering, and there are several if you include scopes that can only be acquired secondhand.

If looking for a lunar & planetary scope they're typically f/12 - f/15 with small secondaries and this really does count. Intes made some at f/8 and f/10, but like Meade/Celestron SCT's, it is not an optimal choice.

All maks are by design perfectly corrected for spherical and chromatic aberration on axis and if well made, should show textbook diffraction patterns at extremely high power. For example the Rumak gives perfectly corrected images over a flat focal plane (nirvana, some would say), whereas the Gregory Mak designs typically have a slight spherochromatism and a curved focal plane, similar to SCT's.

There is as usual the question of the central obstruction due to the secondary mirror and baffles. This varies. Some of the smaller maks have quite large CO, as high as 35% (eg the 102 and 127mm ones from Skywatcher/Orion).

Some designs have smaller secondaries - mine for example is 26%, and some have secondaries around 20% at which point the image is as good as unobstructed.

3. The quality of the optics.

Some manufacturers were awful, some average and some are consistently very good. Over several decades there have been a few premium maks like mine with very high quality optics which are in class of their own.

The point here is that some - notably Intes, Santel, AP, and TEC - consistently produced exquisite optics and these do command a premium. My Mk91 for example is probably the best thing you could wish for, short of a 9" APO.

Intes guaranteed 1/6 wave for standard scopes, 1/8 wave for the deluxe versions. Excellent if you can find one but heavy, built like a Russian tank - crude mechanically but effective.
Santel likewise 1/8 wave or better and with a DPAC interferogram.
Meade - made a 7" Mak Cass LX200, these are excellent optically if you can find one - however need some surgery - throw the fork in the bin and open up the OTA to remove a massive iron weight in the back;
APM Germany - Intes optics (ie superb) in an OTA built buy Matthias Wirth, small numbers only.
Astro-Physics and TEC - don't know if they set a tolerance but they are consistently excellent and beautifully built.
Skywatcher - early ones (2006-8) OK but not great, but the recent examples I've seen are consistently very good.
Orion (Synta) - same as the Skywatcher ones, rebranded
Saxon - Chinese versions included a 150 and 203mm mak, no idea of quality as I haven't seen one. Rare, it seems.
Ottiche Zen (Italy) - good optically but the correctors are not coated. Handmade in small numbers by a craftsman.
iOptron (made by Bosma) - cheap mass-produced Chinese version. Haven't seen one, personally.
Orion UK - do not touch those with a bargepole.

4. Size, weight, portability.

5. The ultimate is Questar, who build a scope designed as a portable observatory in a shoebox, built to last a lifetime, provide guaranteed support seemingly forever (a Questar made in 1957 can be serviced, cleaned, recoated and updated even now). Much admired, for obvious reasons.

6. Issues.

- the heavy corrector - can dew over but because it it is so thick theres more thermal mass, so this doesn't happen as quickly as it does with an SCT. Options include heaters or dewcaps. I use a dewcap and don't need a heater.

- internal tube current off the baffle - as with SCT's and the options is the same - either cool the scope, or insulate it. Insulation works very effectively on mine - it is usually ready to observe as soon as I am.

- focussing mechanism - some maks have moving-mirror focussing (like SCT's) with the usual issues with mirror slop (Skywatcher). Some use moving mirror focussing but got it right (no slop) - Intes, AP, TEC. Others have fixed mirrors and use a focuser bolted on the back (Santel, APM and some Intes) which means the focussing range is limited.

- collimation. Like all cassegrains they are sensitive to misalignment but f you get it right it should stay that way for a very long time.

7. Why use one.

Try mine on a good night and you will understand.

[Ukastronomer]

Why not Orion, I had an Orion Reflecting scope, I was never happy with the focusser and the after sales was crap, any other reasons

[FlashDrive]

A lot of good information there ....!!

I love my Intes MK65 f/10 ... ( fixed mirror )

Thanks Wavey ...:)

[mental4astro]

Greg,

One thing to keep in mind is two scopes, same aperture but different focal ratios, at the same magnification the image will be just as bright. You may know this, but some people can confuse f/ratio as having some visual consequence. f/ratio only matters photographically.

Sure, you won't be able to drop the magnification to get the same wide field with an 8" f/13 Mak as with an 8" f/5 Newt, but it's not like you are looking through a house brick either. Same magnification and with same AFOV, same image brilliance. What can vary though is optical quality, regardless of whether it's a Newt, SCT or Mak, & yeah sure, throw in refractors too.

Wavy has mentioned a lot of the tech stuff around Maks. I'll just relate my visual experiences with Maks vs SCTs.

I had used SCT's for my lunar sketching for many years. I had thought my SCT's were pretty good, even if the assembly of one of them was so poor that the corrector plate was very distorted by a way over tightened retention ring (current SCT owners, read this thread as it may affect your scope (http://www.iceinspace.com.au/forum/showthread.php?t=171466)). I've since looked through Wavy's 9" Santel, and my 7" Intes Deluxe, and the difference is chalk and cheese. My Intes Mak, despite being an inch smaller in diameter, I can push it to 500X and I do not see image degradation, something I cannot do with my SCT and it is now of typical SCT optical quality. And a side-by-side comparison between the Mak and SCT, yes the image in the SCT is a little brighter because of the aperture difference, but the quality of the image, how fine the resolution is I can see in both scope, the difference in subtle contrast variations, and how stable the image is in both, the Intes tears shreds off the SCT. I ended up spending all my time with the Mak and the SCT just sat there, tracking, but with no one looking through it...

No matter the design of a scope, if optical quality is magnificent, then seeing conditions will be less detrimental for visual. If the optical quality is not there, then not all the photons will not be going where they should, so when seeing is not perfect, the photon distribution will be even more erratic, and the image instead of softly waving like a flag in a gentle breeze, will be scintillating/vibrating too making pushing high magnification difficult to impossible to use. But if the optics are schmick, then the image will just gently wave but high magnification will still be possible. This was one thing I came to find out when I tested 6 different Cats to find a new one. This pic below is of the final shoot out between the three shortlisted Cats, two SCT's and the Intes Mak.

242293

Planets, particularly are sensitive to optical quality as it is not just about getting a sharp image, but contrast is often forgotten in the equation. Many of the details are either seen or lost as they are totally dependent on contrast. All the photons need to go where they should, as any stray photons will reduce contrast as well as resolution (coatings & baffling are not the only aspects affecting contrast).

DSO's. Nearly all my DSO experience with Cats has been under light polluted skies. You may think this is a disadvantage, but not really. Instead, it's meant that optical quality needs to be especially good in order to see the best image possible as contrast is the key. Get the optical quality right, and at the same magnification a Mak is good as the very best refractor and Newt around. Get the quality right, and it will mean seeing the skirt around the Homunculus Nebula or not in less than perfect seeing conditions at 200X.

Brands? Wavy has mentioned a few. There are not many Mak manufacturers, but all are boutique optics. Skywatcher though shouldn't be dismissed outright. Whoever it is that is making the 7" Maks for them is doing a stupendous job! They have been refining their manufacturing techniques over the years, and while their earlier Maks were very good (I've looked through these and seen the Enke division through one! :) ), the current crop of 7" Maks are even better. Will other brands that are re-badged Synta scopes be just as good? I cannot say as I have not looked through them. Maybe yes, maybe no - and there is form on the "no" side of things. Saxon at one time offered an 8" Mak, and I only know of one in Western Australia. And the Meade one I suspect is of Synta origin or the same manufacturer as produces for Synta.

Aperture? 7" is currently the largest readily available today. Larger aperture Maks are very rare today. With Intes now ceasing commercial production, and the sets of large diameter optics available to the likes of APM quickly diminishing, large diameter Maks (over 7") are very difficult to come by new. But what size aperture? That's entirely up to you and how deep your pockets are.

Alex.

[gregbradley]

Thank you to Wavy and Mental for the great advice. Most helpful.

So a Skywatcher 180 would be a sweet spot for price, performance and availability? I am wanting a goto visual instrument as I haven't done a lot of visual for some time.

Greg.

[mental4astro]

Yes. And the current model comes with a 2" visual back instead of the 1.25".

Before you buy, try to have a look through one to satisfy yourself that it will be a good match for what you are looking for.

Alex.

[Joves]

I can attest to the Maksutov being a brilliant design.

Whilst my limited time often sees me dragging out the little Skywatcher 127 Mak for brief glimpses at a clear sky, the images it throws out are ridiculously great for the price I paid for it. But of course its aperture is what it is, thus limited. On the occasion that I have the energy to set up my 8” Tec Mak, with conditions allowing, I am always absolutely blown away! Extremely large (and unaffordable to most) Apo views with a more limited field of view (perfect for planets, galaxies, planetary nebulae and globulars) is what I see this scope as being the absolute master of!

Take measures to manage the dew and these things are amazing!!

[Ukastronomer]

8” Tec Mak ????

[mental4astro]

Here's some Maksutov porn up for grabs!! :D

7" Questar on Astromart (https://astromart.com/classifieds/astromart-classifieds/telescope-catadioptric/show/near-mint-questar-7-titanium-classic-fork-mount-and-accessories)

[DeWynter]

The very first image looks like a kids tabletop $50 one. :lol: On the next image you quickly realise why it costs that much! :P

[mental4astro]

Catadioptric scopes have a bad reputation for being difficult to reach thermal equilibrium. They are notorious for being slow.

HOWEVER, there is a change of thinking about both cooling and dew control when it comes to closed-tube Cats, be they SCT's or Maks.

Instead of having them cool, DON'T let them cool!

Have a read through the following thread about insulating closed-tube Catadioptric scopes. It will mean not only not having to wait for thermal equilibrium, but you can begin using your scope at high power straight away, not two hours later.

Insulating Maks and SCT's, and then pimping it (http://www.iceinspace.com.au/forum/showthread.php?t=172245)

Alex.

[FlashDrive]

Alex ....thank you ...I'm going to try this on my Intes Mak

Col....

[Camelopardalis]

Both of my Edge HD SCTs have the vents and have been fitted with TEMPest fans to help equilibrate. They generally don't cause an issue with thermals unless the temperature is dropping particularly rapidly...not especially unusual in winter even in Brisbane.

Another thing with closed tube designs is...don't store them inside. Sure, in the the garage/shed, but not in a spot where they're subject to Sun or other sources of heat. I think it goes without saying that no scope should be left in the Aussie Sun unprotected ;)

The insulation thing is an interesting idea, might have to give it a go this winter...

On topic, all of these exceptional scopes are rare and not inexpensive instruments. The mainstream scopes can be great, but it's subject to random variability in QA. That doesn't mean good ones don't exist...IMO most of the reports (not those from the learned gents above of course!) of poor performing SCTs comes from folk that subject them to large temperature gradients and don't bother to collimate. The difference is night and day.

I, too, have seen the Encke Gap, about 4 years ago from our Sydney back yard, with my Edge HD 8". I wasn't looking for it but noticed it and observed it for some time, then looked it up afterwards. I was stunned. Having thought I was imagining things for some time afterwards, I've subsequently seen it again on those rare good nights with both my Edge HD 8" and Edge HD 11". Brisbane seeing is not usually good for 400x, but it does happen occasionally.

[FlashDrive]

This is a good read ....some of the photos in the thread show how some folks have insulated their Scopes.

https://www.cloudynights.com/topic/605123-insulation-jacket-for-mak/

Credit to the original Poster on CN.

one photo I found was quite amusing ... credit to the poster of photo

Col....

[Joves]

Yep, a Tec MC200 f15.5.

[ariefm71]

A Tak and a Tec... what a great combo

[FlashDrive]

I want it ....:eyepop: ......I want it..... NOW ..!!

[Joves]

Would be even better if they saw some use :rolleyes:

[Joves]

:lol:

:lol:

[mental4astro]

I've got first dibs on Wavy's Santel! :D :D :D

[Wavytone]

No Col... THIS is the stuff dreams are made of...

[FlashDrive]

True.....True Indeed ....!!:)

[FlashDrive]

@ Wavy and @Joves ...... either one....

My TAK FS78 and My Intes MK-65 for your Santel MK91 or the 8" inch TEC MAK.

I'll throw in my Matchbox Car Set at no extra cost. ( Deal Breaker )

1st in gets the swap ...... :D

You can wake up now Col ....it's Morning...:P

Col.....

[Wavytone]

Col there are choices

With some buying and selling you could trade up, there’s quite a nice very collectible example of Zeiss minimalism on AM, fully functional with all accessories and original box in East German communist hospital grey:

https://astromart.com/classifieds/astromart-classifieds/telescope-catadioptric/show/carl-zeiss-jena-telescope-meniscas-1801800-in-wooden-case-include-all-adapters-in-wooden-case

Lewis, stop drooling.

Hard to choose between that vs a nice Questar 7 titanium compete with mount and accessories also on AM. These do not turn up often.

And then there’s this little beastie http://apm-telescopes-englisch.shopgate.com/item/32393331

[Stefan Buda]

Please let me throw a bucket of cold water over this thread before it generates another Maksutov hype.
Back in the nineties I got sucked into one and made a 7.5" Gregory Mak.
Well it turned to be so temperamental regarding thermal control, that I moved on to a DK planetary not long after.
I won't go into details, but it is just about impossible to get a Mak working at it's theoretical limit for more than a few minutes in conditions of dropping temperature.
I know that there are not many big Mak's out there, but I've never seen cutting edge planetary images made with one. Has anyone?

[Wavytone]

Funny you should ask
https://www.cloudynights.com/topic/655947-show-your-mak-casses-deep-sky-pictures/#entry9271071

http://www.astronominsk.org/Planets/Planets_2007.htm
http://www.astronominsk.org/Moon/Moon2008.htm
There's also a composite of the moon made with a Santel that is extraordinary.

And the trick of insulating the OTA - which no doubt seems heretical to many - works a treat on this scope.
I can confess I am toying with the idea of putting an ASI128 or ASI071 on mine as it has a clear 48mm image circle.

[mental4astro]

Interesting points Stefan.

Yes, this is turning into a bit of a Mak love-fest... :rolleyes: A bucket of cold water is a good thing.

Had you insulated your Mak?

The thermal issue is a very real one as you say. Letting closed-tube Cats cool is a confounded problem, with the largest of Cats just refusing to play nice, especially when big temperature differentials exist between starting temp and the ambient temp however much time later. Unless the scope is kept in a cold room, there will always be thermal issues with closed-tube Cats. We've been forcing closed-tube Cats to cool in attempt to force them to behave more like open tube scopes and even refractors. Maybe closed-tube Cats require a different thermal approach.

A few questions are brought up this way. Why are Maks not popular for photo? Thermal issues? Expense? Bad press? Being Russian in origin? Ignorance? I for one had avoided Maks for many years for many reasons: of following a perceived East vs West thing: being so exotic I didn't trust them: seeing that Maks were just about totally shunned in the popularity stakes of scopes: their very slow focal ratio vs the faster and faster trend: price may have been a big factor influencing this. Ignorance though is the one common factor in all of the above other than price. I certainly have changed my opinion about Maks.

Why has this visual quality not translated into photo as suggested? But there are some people who are using Maks, and large Maks at that, for some very high quality lunar and planetary photography. English language forums are the worst representatives for Mak photography too!!!

Insulating closed-tube Cats has made a big difference, especially for Maks. Open tube scopes are a totally different thermal proposition. But with this change in now insulating Maks, maybe it will see a return to Maks for photo? Maybe Maks, and SCT's, needed a different take way of dealing with their thermal characteristics, to which the traditional "cooling" ones are not best practice for them. And insulating them is the trick to slow their cooling rather than forcing a cooling process. This requires a BIG change in the conventional thinking about how to deal with heat in scopes, and how many people will be willing to accept a change in thinking?

[Camelopardalis]

Don’t see a problem with a love-fest, so long as we don’t lose perspective. It’s always nice to dream :lol:

A glint of the perspective is that there are few of these in Australia making them somewhat unobtainium. Where’s the fun in bragging rights when you can’t share the love? :shrug:

Regardless of their magical qualities, mass-produced SCTs are just plain easier to get hold of, in Australia or otherwise, and more gentle on the wallet.

Then there’s the paradigm of resolution in lucky imaging. Getting a good enough SCT just isn’t that hard. I can’t imagine SE QLD is that unique, but I know a number of folk with good scopes - all of which I’ve looked through. My own scopes I don’t regard as particularly special, but the results speak for themselves.

Planetary imaging comes down as much to robust technique as anything, other than the seeing of course. A common weapon of choice is a C14...not outrageously expensive, relatively lightweight, a lot of light grasp and easy to reach the realm of high resolution planetary imaging with a simple 2x Barlow.

When we start talking deep sky imaging, Maks are just too slow. SCTs too. Imagers don’t chose to image at f/10. This is what makes larger newts, with all their flaws, more appealing as it’s not hard to get a seeing-limited focal length in the region of f/4-5. Advances in sensor technology open up reasonable exposure times to slower scopes, but faster f-ratio will always have the upper hand.

Theoretical superiority is one thing, but practical accomplishments are another...

[Stefan Buda]

I would not call the linked images cutting edge, for 230 mm aperture, but I was thinking along custom built Maks. There must be some larger aperture ones out there but no results to show.

What sets the Mak apart from other Cats is the very thick front lens and that is its undoing. Insulating the tube may resolve internal thermal gradients, but if the front lens is above or below ambient, it will have a proximity layer, on the exposed surface, messing with its performance. Though, it won't be as severe as the one caused by the proximity layer on a primary mirror because in case of a mirror the light goes through it twice.

And these are expensive scopes and people should not be sucked into hypes based on subjective comments - like I was.

Please do not evaluate a Mak against another Mak. Do it against a similar aperture, but good, Newtonian using similar magnification - you may be surprised.

[Stefan Buda]

I ended up cutting two large holes into opposite sides of the CF tube for ventilation. That helped but as soon as the front would reach thermal equilibrium, it would start fogging up.
Another experiment I did, was to store the scope in a cold place during the day and then take it outside to look at Jupiter exactly when the ambient temperature crossed over the scope's storage temp. The view, needles to say, was excellent but lasted less than 10 minutes.

[Joves]

Then there is the plain fact that, despite whatever scope you may own, Nick will always come in to tell you that his Santel is better! 😀

[Joves]

Excellent post!

[Joves]

Another great post!

There is nothing magical about these Maks that should see anyone feel they are SOOOOO much better than a large SCT. Sure, I’m happy with mine but, for the price I paid, I’d sure well want to be. Is it exponentially worth the difference between its cost and that of a much larger SCT... I’m not sure, I don’t own the latter. I imagine not....

[Joves]

Very interesting, Stefan.

Would you say that these scopes are best suited to Summertime (or, at least warmer climate) viewing?

[Ukastronomer]

Is this problem not the reason why scopes such as my Edge HD Celestron have tube vents

[mental4astro]

Yes, Jeremy.

This solution follows the conventional thinking around forcing scopes to cool. And while in principle it works, it is not necessarily best practice, but as a selling point it is excellent because this is what people know and expect. It still requires a waiting time and constant monitoring.

Yet the insulation route is totally passive.

Dew formation is a separate matter though. All scopes are susceptible to it, thought needs to go into it, and designed specifically for each scope type, though the principles followed are the same.

As for dealing with dew, one has three options: 1, heating strap around the corrector -not my favourite as you want the scope to cool (slowly or quickly) and then a heat source is re-introduced around an active lens element: 2, rig up a blower system that will evaporate dew, either heated (care needed), or at ambient temp: 3, set up scope at a dew-free location - dew and astro ARE NOT inseparable bed fellows. The dark site location my observing buddies and I use, we are still to experience a night of any dew on our optics in now more than 7 years, a on all types of scopes, Maks included. All about site selection and time into these investigations. Dew-free astro is possible.

One thing I don't want to do is create the impression that I'm saying Maks are the perfect scope. They are not, in the same way no particular scope design is. Maks fill a niche and it is up to the individual to figure out if a Mak satisfies a particular requirement they have. I have some 14 scopes, of these only one Mak, and I still have an SCT as IT fills a niche for me with outreach. And yes Dunk, I do agree with practices being equally important to extract the very best from whatever scope one is using, both photo and visual.

Alex.

[mental4astro]

I forgot to add to the fans on SCT's, it works, but there is an alternative, especially if fans are not an option for you or your scope.

[Camelopardalis]

They can work remarkably well, with the addition of fans (I added the TEMPest units).

I typically switch them on when I setup the scope and depending on the conditions, often leave them running through the night.

Brisbane is notoriously humid in summer but because of the lack of huge temperature swings, I don’t use a dew heater in summer. In “winter”, which is usually dry, it works out more risky because the temperature drops can be quite rapid, especially just after dark.

You might need to keep your wits about you in the UK, as if there is a lot of moisture in the air the fans can draw it inside the tube...one cool winter evening when I lived in Sydney, I had the corrective dew up on the INSIDE :eyepop:

Anyhow, who wouldn’t love a good Mak?! I wouldn’t say no, but (at risk of being on topic) I think they’re more of a visual pleaser. I don’t remember seeing any great planetary images with a Mak. Sure, plenty of images out there with a SW 127, but with telescopes we’re always caught by The Fever, and a big SCT or new (or <insert design here> ) is always going to capture the imagination more than a 6 or 7” Mak...rightly or wrongly.

[beren]

Are the Vixen VMC worth consideration, not sure if they are true Maks ? I have a VMC200l which I have been happy with

[Wavytone]

Diffraction from the vanes and the large CO are the issues with the VMC design. An SCT is probably better (no vanes).

[Ukastronomer]

Then why do all Sc and MC scopes not have such vents or insulation

[Stefan Buda]

Hard to tell. All locations are different.

When your thick Mac corrector lens departs by more that a couple of degrees from ambient temperature, it will have a flowing proximity layer on the front surface no matter how well the tube is insulated. If the tube is metallic and not insulated, then you will have a similar boundary layer on the back surface of the corrector as well. And one on the primary too.

[Ukastronomer]

Surely it is horses for courses isn't it ?

NO scope is perfect, refractor, reflecting SC or any other, a SC is not better or worse than an MC or a "VMC" they are suited to the jobs they do.

No car is perfect, you chose the car depending on your needs, to me a big 4x4 is pointless to others it is a must

[Wavytone]

Aaron seeing isn’t seasonal - but the prevailing wind direction and the terrain upwind of your observing site will influence it. Some sites simply won’t be much good while others can be good, often.

IMHO there are three factors - transparency, seeing, and what’s up high. At a dark sky site, if the transparency is good but the seeing isn’t, just stick to low power and enjoy the DSOs.

When the seeing is very good, enjoy. But remember there’s no point in high magnificent on objects lower than 60 degreeed above the horizon.

[Joves]

Thanks Nick, good advice.

[doug mc]

Last night I was out with my GSO 8 inch classic cassegrain. Dewing was quite heavy. The tube was almost dripping, but at no time was i bothered by it. I gave up on SCTs because of that problem. Was checking a few doubles around Crux. Beautiful intense diffraction patterns. If you have the bank balance, go the Santel, Intes, Tak way if you can, but i am happy with this scope. There is no magic between different types of scope, it's mostly about optical quality.