Mak-Cass versus Schmidt-Cass Systems

[JamesF]

Just now, Pete Presland said:

I didnt see the back reference, both of them are quite heavy. I am ok with the C9.25 at the moment, but in 10 years time though who knows? It is something that i think about more and more even at 54 yrs.

There's a video on youtube of a method for working around this problem for large SCTs, though perhaps it still wouldn't suit everyone.  I believe it involves putting the OTA "corrector down" on a chair or stool and then moving the mount axes to meet it.  I'll see if I can find it.

James

[Alien 13]

Here is an off the wall thought, Maks get better with diminishing aperture and SCTs get better with increasing aperture, the crossover point is around 4-5 inches me thinks..

Alan  

[JamesF]

Here's the video.  He's showing off, and using a C14.  Perhaps he thought a C9.25 would be too easy.

James

[Avocette]

4 minutes ago, Alien 13 said:

Here is an off the wall thought, Maks get better with diminishing aperture and SCTs get better with increasing aperture, the crossover point is around 4-5 inches me thinks..

Alan  

More explanation please!

[Alien 13]

11 minutes ago, Avocette said:

More explanation please!

Its just an observation, nothing beats something like a 90mm Questar Mak for APO like performance but things get more difficult with larger apertures from cool down and mounting issues and the larger Maks have lower f/ratios which reduces contrast a little.. The poor contrast with SCTs seems to improve with aperture and they can be made much bigger..

Alan

[Louis D]

46 minutes ago, JamesF said:

Here's the video.  He's showing off, and using a C14.  Perhaps he thought a C9.25 would be too easy.

James

That still requires a dead lift of 46 pounds to a height of about 2 feet.  I can just manage that, but it leaves me with a backache.  I don't know about the OP's back situation.  Hopefully, he'll chime in with a more specific weight limit.

[Mr Spock]

As someone with severe back problems I can say a C9.25 is easy to lift - the mount it has to go on is impossible to lift.

[Ags]

22 minutes ago, Mr Spock said:

As someone with severe back problems I can say a C9.25 is easy to lift - the mount it has to go on is impossible to lift.

Use it handheld then... 🤣

[JamesF]

39 minutes ago, Louis D said:

That still requires a dead lift of 46 pounds to a height of about 2 feet.  I can just manage that, but it leaves me with a backache.  I don't know about the OP's back situation.  Hopefully, he'll chime in with a more specific weight limit.

Yes, I agree that not everyone will be able to manage that.  He does offer an alternative solution though

James

[Stephenstargazer]

45 minutes ago, Alien 13 said:

Its just an observation, nothing beats something like a 90mm Questar Mak for APO like performance

Well except a good Fluorite APO! I am lucky to have both so it's a fair observation !! Back to the question, I deifinitely agree that an economic 150mm Maksutov  of reasonable quality is hard to beat for the price and ease of mounting. That is what @Goldfinger proposed and I dont see that either that scope or its mount would trouble many backs. As long as he avoids carrying tripod, mount, scope and accessories in one go (which is never necessary, even if occasionally convenient). Likewise seated viewing is a 'no brainer' for comfort.

As someone who started with a 140mm Maksutov (OMC) I think his choice should provide years of use and many observable objects from planets to DSOs  until he develops a more specific interest. Meanwhile if he pines for wider views (the main Maksutov disadvantage) I suggest getting some binoculars, an asset that does not become redundant for any astronomer, ever.

[michael.h.f.wilkinson]

My C8 has been my all-round visual scope for several decades (over 25 years of service), very easy to lift (5.3 kg, 11.6 lbs), collimation is rock solid. I have a 6" F/5 Schmidt-Newton for wider views, and an APM 80 mm F/6 APO triplet for even wider stuff, and solar observing. I have used a Questar 90 mak-cass (not mine). Excellent little scope, which can't touch the amount of detail my C8 can bring out in good seeing (neither can my APO triplet, aperture is king on planets). Note that the Questar has 31% central obstruction, the C8 33% Not a big difference.

I have thought about getting larger aperture scopes (and might still do so), but I do not think the C8 is going anywhere soon, especially when it can produce these kind of planetary images.

[Robindonne]

On 23/05/2021 at 15:57, johninderby said:

Any discussion of Mak vs SCT should also include the Classical Cassegrain. The Classical Cassegrain while an old design has only recently become available in a competitively priced version. I’ve had an 8” SCT and a Skymax180 but have now moved to an 8” Classical Cassegrain. A great performer with no dewing problems and quick cool down and a proper crayford focuser. wouldn’t want to go back to the Mak or SCT in the 8” or there about size range.

What is your opinion on the views when extending the focallength for e.g. the CC8” from f12 to you name it.  Do you think a good focal extender like the powermate will bring the view to the same quality as a scope thats off the shelve in a longer focallength?

Would a C8 f/10 when extended x1.2 give the same view as a CC8” f/12?

I hope its informative for the op’s question but also for my doubt when seeing a Meade sct of 10” or larger show up on the used market having a shorter focallength.  Will it be as versatile to have a short focallength sct + Powermate as a long focallength sct + Reducer?

 

Edited May 24, 2021 by Robindonne

[johninderby]

Haven’t used a a focal extender on the CC8” but it works very well with a barlow. I’m thinking an ES 2x extender ( or clone) would be a good choice.🤔.

Edited May 24, 2021 by johninderby

[michael.h.f.wilkinson]

8 hours ago, Robindonne said:

What is your opinion on the views when extending the focallength for e.g. the CC8” from f12 to you name it.  Do you think a good focal extender like the powermate will bring the view to the same quality as a scope thats off the shelve in a longer focallength?

Would a C8 f/10 when extended x1.2 give the same view as a CC8” f/12?

I hope its informative for the op’s question but also for my doubt when seeing a Meade sct of 10” or larger show up on the used market having a shorter focallength.  Will it be as versatile to have a short focallength sct + Powermate as a long focallength sct + Reducer?

 

F/10 or F/12 makes very little difference, especially if quality EPs are used. The views of planets through my C8 with e.g. a Pentax XW 10 or XW 7 are excellent. Even F/6 or F/8 should not be a problem for quality EPs. The above image of Jupiter was taken with a Meade TeleXtender, which works fine, but I cannot see the difference between the image obtained by a 14mm Delos with 2x TeleXtender and XW7 without. The great advantage of shorter focal length is the wider field of view you get. My C8 at F/10 gives me a maximum field of view of 1.34 deg in a 2" EP, whereas the classical Cassegrain would give 1.17. By contrats, going to F/15 as with certain Mak-Cas designs gives only 0.89 deg FOV.

[Alan64]

https://www.telescope.com/Orion/Orion-StarSeeker-IV-127mm-GoTo-Mak-Cass-Telescopes/rc/2160/e/422.uts

https://www.youtube.com/watch?v=XzKHBFHsgkM

 

[Goldfinger]

Thanks so much everyone who replied. I've narrowed down my search. While I would love to have a Celestron 6se telescope it's a little out of my price range.

So I found these two. Both are 6" Orion models.

https://www.ebay.com/itm/Orion-Star-Seeker-IV-150-mm-Kit-w-Orion-Lens-Kit-/174782720683?_trksid=p2349624.m46890.l49286

https://www.ebay.com/itm/Orion-StarSeeker-IV-150mm-GoTo-Mak-Cass-w-Controller-5mm-Wide-Field-Eyepiece-/334010735531?_trksid=p2349624.m46890.l49286

If appreciate any opinions on these two telescopes...pros and cons..

 

[nfotis]

8 minutes ago, Goldfinger said:

Thanks so much everyone who replied. I've narrowed down my search. While I would love to have a Celestron 6se telescope it's a little out of my price range.

So I found these two. Both are 6" Orion models.

https://www.ebay.com/itm/Orion-Star-Seeker-IV-150-mm-Kit-w-Orion-Lens-Kit-/174782720683?_trksid=p2349624.m46890.l49286

https://www.ebay.com/itm/Orion-StarSeeker-IV-150mm-GoTo-Mak-Cass-w-Controller-5mm-Wide-Field-Eyepiece-/334010735531?_trksid=p2349624.m46890.l49286

If appreciate any opinions on these two telescopes...pros and cons..

 

These are quite different models.

The first one is a Newtonian reflector (around 800mm focal distance, if I remember correctly) - the sideways focuser / eyepiece is a giveaway, while the second one is a Maksutov.

The Skymax 150 gives 1800mm focal distance and an f/ratio of f/12. This gives a contrasty refractor-like image on the planets and the moon.

Forgot to mention, this field of view calculator will give you an idea of what to expect with the framing of planets etc:

https://astronomy.tools/calculators/field_of_view/

You will probably need a zoom eyepiece - the SVBONY 7-21mm zoom is quite nice and works very well with these Maksutovs (using it with both my Skymax 127 and 180).

 

N.F.

 

Edited May 27, 2021 by nfotis

[Louis D]

The Mak is the much better deal of the two.  The Newtonian seller wants new pricing for used equipment while the Mak seller is applying a proper discount against the new price.

The Mak will also have much better resale value down the road.  Those cheap Newts don't hold their value at all.