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5" APO verses BEST 7" MAK CASS

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#76 SeattleScott

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Posted 23 January 2019 - 09:07 AM

A Mak has more like >80% if taken everything into account and with modern coatings.

And this still gives you an aperture of 150mm for your 180mm Mak: sqrt(170*170*0.8) . 170mm is the effect of obstruction.

And your 5" apo has at most 95% light grasp if you are lucky (so 120mm effective).

Sure the gap between 120mm and 150mm is not mega large but will be noticeable (not to speak from the better resolution capabilities of the larger instrument if seeing permitting).


The Maks often have had standard coatings instead of enhanced coatings. At least that was the case six years ago. The enhanced coatings have s little more light scatter apparently and may not be considered as good for planets, and many people get Maks for planets, so it seems different coatings were often employed.

Scott
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#77 Stopforths

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Posted 23 January 2019 - 12:35 PM

I have 2 mounts and often set the vixen 115eds and sw180 up next to eachother.  Vixen in a superb scope no question but can't do the impossible and beat a good 180mm Mak Cass.

 

 

I also have a 10 inch f10 intes micro with tested 1/8th wave p-v strehl (.97 strehl) and that is a stunner in good conditions.  Unfortunately I don't have a 7-8inch apo to compare but suspect  it would be close.  Certainly its ahead of a 6 inch apo according to its previous owner who had a 6 inch tak fs as well and sold both would you believe!!  

 

The obstruction is around 34-35% I consider it as close to a 10 inch questar as you could get just love it.  Jupiter at 280 x with a quality eyepiece is amazing.  I don't go higher on Jupiter personally there is a lot to see at that Magnification.  Mars was a disappointment because of the dust storm.    Saturn the detail on the planet and the rings has to be seen to be believed it has a lot of colour and light contrast on the globe that becomes visible.    


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#78 Magnetic Field

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Posted 23 January 2019 - 01:35 PM

I have 2 mounts and often set the vixen 115eds and sw180 up next to eachother.  Vixen in a superb scope no question but can't do the impossible and beat a good 180mm Mak Cass.

 

 

I also have a 10 inch f10 intes micro with tested 1/8th wave p-v strehl (.97 strehl) and that is a stunner in good conditions.  Unfortunately I don't have a 7-8inch apo to compare but suspect  it would be close.  Certainly its ahead of a 6 inch apo according to its previous owner who had a 6 inch tak fs as well and sold both would you believe!!  

 

The obstruction is around 34-35% I consider it as close to a 10 inch questar as you could get just love it.  Jupiter at 280 x with a quality eyepiece is amazing.  I don't go higher on Jupiter personally there is a lot to see at that Magnification.  Mars was a disappointment because of the dust storm.    Saturn the detail on the planet and the rings has to be seen to be believed it has a lot of colour and light contrast on the globe that becomes visible.    

I posted it many times in the past: Intes (or the Russians in general) missed a trick by not staying in business.

 

They would really add to the joy of the conscious amateur astronomer who wants something good at a reasonable price:***

 

f/10 and say lambda/6 throughout the range:

 

- 110 mm

- 125 mm

- 150 mm

- 180 mm

 

I know people hate me for that: but it has to be  f/10 (good compromise).

 

 

***There are not many who would pay for a Questar or Astrophysics. Nothing personal but just a fact of live (people have other hobbies or commitments, e.g. mortgage etc). However, there would be many to pay for an Intes and everyone understands it that it cannot be cheap Chinese pricing and has to be something that reflects manufacturing costs in Russia.


Edited by Magnetic Field, 23 January 2019 - 01:38 PM.

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#79 vahe

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Posted 23 January 2019 - 02:36 PM

I posted it many times in the past: Intes (or the Russians in general) missed a trick by not staying in business.

 

They would really add to the joy of the conscious amateur astronomer who wants something good at a reasonable price:***

 

 

Agree with your above comments which also reminds me of another comment by Markus Ludes who imported Russian Maks, in his own words;

.

"Intes Micro Maks are not very expensive, but they are not also cheap. If you think they are very expensive, name us another company worldwide who makes such high quality Maks for less price, there are non ! Zeiss makes 150 and 180 or Questar cost a lot more, so Intes Microis for the quality they deliver inexpensive."

.

Vahe


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#80 CHASLX200

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Posted 23 January 2019 - 06:54 PM

In bold.

 

Okay the Questar has proven optics and I guess it costs as much as the AP EDF 130.

 

Anyway one more anecdote that a Maksutov is indeed a very good choice for observing planets.

I had a few Maks that were super on the planets. I still like a well made Newt the best for high power planet work and the best bang for the buck.


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#81 Bomber Bob

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Posted 23 January 2019 - 09:20 PM

Size for size, the superb APO wins.

 

That's been my experience.  I bought my Questar for my Really Old Age.  Yes, it's an observatory in a shoebox, BUT it requires a tripod.  It's grab & go, BUT so is my Vixen FL80S F8 fluorite on a Polaris mount + wood surveyor tripod.  And, the APO is more versatile, and delivers finer planetary views at 250x than the Questar.  OTOH, the new Questar 5 is on its way...


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#82 De Lorme

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Posted 24 January 2019 - 12:57 AM

Bomber Bob, did you buy the Questar 5 because of the convenience factor?  Just how much better is the Questar than the apo?  The Questar cost so much more than a apo and a nice small portable mount. What do you understand that I don't?

 

Thanks, De Lorme



#83 SkyRanger

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Posted 24 January 2019 - 09:07 AM

Questar 5?  Is this something new or something vintage?  I can’t find it on the Questar website.

 

Gordon



#84 Magnetic Field

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Posted 24 January 2019 - 09:10 AM

Bomber Bob, did you buy the Questar 5 because of the convenience factor?  Just how much better is the Questar than the apo?  The Questar cost so much more than a apo and a nice small portable mount. What do you understand that I don't?

 

Thanks, De Lorme

Interesting.

 

Didn't know that Questar now makes 5" scopes.

 

I once owned a 5" UHTC Meade ETX. It was optically very good. However, I was surprised by the bulkiness (fork mount and optical tube) compared to the ETX-90. The ETX-90 though wasn't up to the task and not very useful (90 mm is really a very small aperture). My now Vixen VMC 110 with 110mm aperture is the lowest I will ever go I think.

 

I also once owned a 6" Intes Maksutov long time ago (sold it to a friend and I have been regretting it since then).



#85 Erik Bakker

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Posted 24 January 2019 - 09:42 AM

The Questar 5 is not in production yet, but under development. Realistically, production should commence in 2020.


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#86 Asbytec

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Posted 24 January 2019 - 10:11 AM

We hear folks regretting selling their Mak. I feel the same way and have not sold mine. Hope not to feel that regret.

When I first put my Orion Mak through its paces years ago, it began to dawn on me what I had. A good scope in good seeing. Maybe optimistic, but I thought of it as a poor man's Questar. I tested a friend's ETX 90, too. Very sharp. Took magnification very well.

Id argue it's as good as Intes standard which advertises 1/6 pvw. Likely not as good as the deluxe. At least this sample, maybe got lucky. But folks seem to like them more often than not.
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#87 chuckscap

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Posted 26 January 2019 - 11:08 AM

Size for size, the superb APO wins.

 

That's been my experience.  I bought my Questar for my Really Old Age.  Yes, it's an observatory in a shoebox, BUT it requires a tripod.  It's grab & go, BUT so is my Vixen FL80S F8 fluorite on a Polaris mount + wood surveyor tripod.  And, the APO is more versatile, and delivers finer planetary views at 250x than the Questar.  OTOH, the new Questar 5 is on its way...

 

That may be true but how much does a 7" TEC APO cost including the mount you need to hold it, vs a superb 7" Mak and it's mount.   There's a point (in size) when an APO makes sense for very few amateurs.    I think going from 6" to 7" is the break point.


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#88 Bomber Bob

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Posted 26 January 2019 - 12:13 PM

I think going from 6" to 7" is the break point.

 

I agree.  When I joined the B'ham club back in the 1970s, 6" aperture was the decision point for going from refractors to reflectors.  Now with 6" F8 APOs, 7" makes sense.  

 

I bought the Questar for its quality, convenience, integration, etc. -- like lots of others.  Even used, buying an 80mm fluorite + mount + case isn't necessarily that much cheaper -- and I got all of that gear with the Questar.  But the Vixen has a wider variety of excellent views, and is stabler in temp changes.


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#89 chuckscap

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Posted 26 January 2019 - 03:49 PM

I'm very happy with my TEC 7 Mak.   It's a gorgeous telescope optically and cosmetically.    I still have my Orange C14 but it doesn't get out much.    I sometimes miss my Mewlon 250 but with all the fires in the Western states during the summer I literally didn't use it for three summers.     I can still look through a club members AP 180 APO every now and then :)



#90 De Lorme

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Posted 26 January 2019 - 04:58 PM

Hello everybody, 

 

Rock22 let me know there was a 7" Sky Watcher Mak Cass{as a second}on Amazon so I bought it.  The Baader 2" visual back ,regal collimation cap, and the scope should all be here by next Wednesday{the 30th}. It didn't come with the 28mm

eyepiece but I have a Meade 20mm UWA that I'll be using as a finder eyepieces anyway.

 

Will let you know hopefully by Friday how it measures up tot the ES 5" FCD100.

 

Thanks for the help and Clear Skies,  De Lorme


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#91 Richard Whalen

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Posted 27 January 2019 - 12:29 PM

My TEC 8" f15.5 can easly go beyond 100x per inch with no image breakdown on an excellent night. Rarely go that high except for a few doubles, Saturn, and Uranus/Neptune. Strehl .997


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#92 spongebob@55

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Posted 27 January 2019 - 03:00 PM

Hello everybody, 

 

Rock22 let me know there was a 7" Sky Watcher Mak Cass{as a second}on Amazon so I bought it.  The Baader 2" visual back ,regal collimation cap, and the scope should all be here by next Wednesday{the 30th}. It didn't come with the 28mm

eyepiece but I have a Meade 20mm UWA that I'll be using as a finder eyepieces anyway.

 

Will let you know hopefully by Friday how it measures up tot the ES 5" FCD100.

 

Thanks for the help and Clear Skies,  De Lorme

De Lorme,

Good luck with your purchase.  Looking forward to your report.  If you could, let me/us know how doubles look, specifically if there are any or bright diffraction rings or circles around the stars.  I want to know it this shows up in a 180mm f/15 since I bought a 127mm and they were so bad that I couldn't enjoy the views.  All bullseye targets in focus.   I had a Orion 180mm a number of years ago and the views were great, but I wasn't into doubles then so I don't remember the views, just spectacular planets, moon and tight clusters.

To you others on this thread with 7" + Maks, can you chime in about how doubles look in your Maks?  Thanks

Regards

SB



#93 Richard Whalen

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Posted 27 January 2019 - 03:43 PM

In mine you see the disc and one very faint diffraction ring. As good as any APO Ive used, better than most. Have spilt equal doubles clean down to .53 arc seconds, and figure 8 down to .49 if star info is accurate?


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#94 luxo II

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Posted 28 January 2019 - 12:32 AM

De Lorme, the last SW7” I had was extremely good and would work to Dawes Limit (80X per inch) without issue.

On typical bright stars it typically showed the Airy disk and one ring; on a really bright example (southern hemisphere) Alpha Crucis (mag 0.76) it shows 2 rings.

I’ve had 3 and seen other recent examples of this scope.

Suggest you enquire as to the age of the one you are considering - early ones (2006) were not so good as the recent ones which have been consistently good and I would have had strehl around 0.94 or so. Not as good as Richards TEC or my MK91, but those scopes are unicorns, not mass-produced.

Edited by luxo II, 28 January 2019 - 12:39 AM.

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#95 Freezout

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Posted 28 January 2019 - 02:47 AM

It didn't come with the 28mm eyepiece but I have a Meade 20mm UWA that I'll be using as a finder eyepieces anyway.

 

De Lorme,

Congratulations on your purchase, but the 20mm will still give you a magnification of 135x and a FOV of 0.61deg, that's quite tight for a finder eyepiece no? I hope it comes at least with a RACI?

I use a 50mm Erfle as finder eyepiece in my Mak, it works perfect. And it's 800mm FL less than yours.  



#96 Asbytec

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Posted 28 January 2019 - 04:00 AM

I've had great luck star hopping to objects with a narrower MCT FOV. Starting off in the finder (unfortunately not RACI) which is centered on my smallish 66 degree True FOV and smaller AFOV at 75x. Find a good star in the finder, star hop till close, then switch to the 25mm Plossl and star hop the last bit. 


Edited by Asbytec, 28 January 2019 - 04:08 AM.

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#97 echan

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Posted 29 January 2019 - 03:18 PM

The allure of the Mak-Cass is real to me, as my observing interests are mainly planetary.  They are short, easy to mount, and their long F/L makes it easy to achieve the magnifications needed.  I owned a TEC6 f12 which I compared extensively with my 4" and 5" apos.  I concluded that for planetary it was likely equal to a 4.5" apo.  My experience with the TEC6 led me to purchase a TEC8 f15.5.  I used that to compare with my 6" and 7" apo and concluded it was probably the equal to a 6.5" apo for planetary.  Fast forward to today and I have a TEC7 f15.  Given the established data points, if one extrapolates the performance it would therefore be a safe assumption that this quality 7" MC would be the equal of a 5.5" apo for the planets. Certainly the TEC7 would outperform a 5" apo.  I've had mine out with my 130GT and can confirm this to be so.  Again, I can attest only to planetary.

 

Some notes from the field:

1) MC's need significantly more time to cool down. As such, not an optimal quick peek scope.

2) MC's are more prone to be affected by seeing by virtue of the CO. On bad-seeing nights, one would probably do better with a 4" apo than a 6" MC. Same holds true for a 5" apo vs a 7" MC.  Apos are more consistent more often. 

3) The TEC8 f15.5 gathered significantly more light than the 6" apo. Whereas I found Jupiter too dim at 300x with the apo, it was still pleasing with the MC.

 

Just my experience, hope it helps.

 

-Evan


Edited by echan, 29 January 2019 - 03:27 PM.

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#98 De Lorme

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Posted 29 January 2019 - 10:54 PM

Thanks Evan for those comments. I have a ES 5"FCD100 which I really like but wanted just a little more aperture but not willing to buy either the APM 5.5" doublet which uses FPL53{a half inch just isn't worth the extra $1300} as one of it's elements or there 6" that uses FPL51 {which to me not worth the $1200 more} because I would still see color{I did with the ES 5" FPL51}.   I had heard that Mak Cass could reach the level of an Apo so I started doing some research.

 

I didn't see comparisons saying the Mak Cass could not surpass an apo but just the opposite. And the reviews on the 7"

Sky Watcher were quit good which is why bought it rather than the Orion.

 

De Lorme



#99 luxo II

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Posted 30 January 2019 - 04:16 AM

1) MC's need significantly more time to cool down. As such, not an optimal quick peek scope.

 

The time for cooling is now a myth IMHO. An MCT (or SCT) with insulated OTA will be ready for high power observing before you are.

 

"... Apos are more consistent more often...."

 

This is related to optical quality (strehl).

 

What I have noticed in side by side tests with several scopes of the same aperture at the same site on the same object, same conditions, is that premium scopes with very good optics - strehl better than 0.95 - are significantly less affected by seeing than scopes with lower strehl.  

 

When comparing the effects of seeing on scopes of significantly different aperture you really must make sure both scopes are working at the same magnification. Otherwise it is as unfair comparison.

 

Ultimately however IMHO refractors are overrated, expensive and easily outperformed by good reflectors - newtonians or MCTs particularly.


Edited by luxo II, 30 January 2019 - 04:31 AM.

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#100 De Lorme

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Posted 30 January 2019 - 02:54 PM

Thanks luxo II for posting your experiences also.  The Sky Watcher should be here by the end of today.




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