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Astro-Physics 10" Mak-Cass

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#451 Derek Wong

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Posted 01 September 2019 - 11:24 AM

AP Mak Panther.jpg

 

I finally got decent seeing without clouds.  Here is the AP Mak on the Panther TTS 160.  The photo angle is unusual, and then I realized that I had to reverse the scope on the mount.

 

There were some vibrations, acceptable to me and my friends but some would not be as happy.  I think this scope is at the upper limit of this mount's capacity.  I am going to try to get a smaller and shorter dovetail which should help things.  Loading and unloading the scope horizontally is a joy.  The mount works beautifully with its step and slew functions.

 

The seeing varied between 3/5 and moments of 4/5, and the temperature dropped 10 degrees in 2 hours.  Initially, I had the back on the scope but after a while I exposed the mirror to the night air.  The scope followed temperature changes fairly well, much better than a big 8-9" refractor but not as well as a 4-5" refractor..The night was not good enough at mid to lower altitudes to allow high enough powers to really test the scope, but Jupiter and Saturn had moments of great clarity at 167x.  I did an abbreviated star test at 295x near the zenith and saw similar patterns to the Maksutov images in the second edition of Suiter.  The Maks have some high order balanced spherical aberration that detracts little from the Strehl but causes asymmetry in the test, and that mixed with less than perfect seeing and some thermals made it more difficult to interpret.  In the first version of the Mak, Roland spent a long time aspherizing some of the surfaces because he was afraid of what the star testers would say, but it made no difference at the interferometer.  Here is an ancient post and thread that discussed these things (unmoderated discussions have huge flame wars but are interesting at times).  Note that this was before the second edition of Suiter came out, and I am sure the chapter in the second edition was in part inspired by this discussion.  I am mainly posting this so people who see an asymmetric star test don't freak out.

 

https://groups.googl...04/cDZl3wbrjb8J

 

In any case, I'm going to concentrate on in focus images with this scope but I will need to wait for next year spring for good planet seeing.

 

Derek

 

PS The mechanics of this scope are amazing, as they should be!


Edited by Derek Wong, 01 September 2019 - 11:26 AM.

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#452 Gleason

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Posted 01 September 2019 - 02:23 PM

There are so many local sources of thermal disturbance when observing from an urban area.  Rare too is sub arcsecond to arcsecond seeing to afford perfect star images in my experience with the 6mm - 10mm Delos eyepieces and the MCT.  My understanding is that Roland took considerable time hand aspherizing the optics this time around.  That being said, I would sure like to read more observing reports from the new MCT owners so that we can all compare notes.  Not sure what happened, but maybe poor weather in general has prevented serious observations?  This much I can report. The views of M42 with my 21 Ethos eyepiece is spectacular in contrast and star sharpness.  Difficult for me to describe here, you just have to look through it to believe it. The Trapezium multiple star burning an a blue-green sea of glowing gas. Subtle and brilliant star colors, gray to black molecular clouds like waves on an ocean.     


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#453 Paul Hyndman

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Posted 01 September 2019 - 08:07 PM

Thanks for the SAA link, Derek... a nice trip down memory lane (nicer still, in that this time AP sent one of those puppies my way).



#454 Daniel Mounsey

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Posted 01 September 2019 - 11:53 PM

Nice report Derek. Sorry I couldn’t make it. Next time.

#455 Richard Whalen

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Posted 02 September 2019 - 02:17 PM

Derek,

 

Did you happen to use the big refractor during the same observing period? Did you notice any difference in seeing effects between the two, like one was more effected than the other? 



#456 dr.who

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Posted 02 September 2019 - 07:45 PM

Nice report Derek! Thank you!



#457 Yu Gu

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Posted 03 September 2019 - 02:45 PM

Now several of you have 10" AP MCTs up and running and I assume most of you have owned or used 6" class APOs in the past or concurrently, what's your opinion on the differences between the two on planetary observation?

Gu


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#458 Gleason

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Posted 03 September 2019 - 09:42 PM

Think of the MCT as a long focus 9.5" color free refractor and all that goes along with that equation when comparing to 6 and 7" refractors in the f/7 or f/9 range. JG.
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#459 Yu Gu

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Posted 04 September 2019 - 07:38 AM

Was that in theory or from direct observations? Most of us do not have access to 10" AP, 9.5" APO and the tropical seeing though...

I would love to hear some observation reports from the users. 

 

Think of the MCT as a long focus 9.5" color free refractor and all that goes along with that equation when comparing to 6 and 7" refractors in the f/7 or f/9 range. JG.



#460 bobhen

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Posted 04 September 2019 - 08:31 AM

Now several of you have 10" AP MCTs up and running and I assume most of you have owned or used 6" class APOs in the past or concurrently, what's your opinion on the differences between the two on planetary observation?

Gu

HERE is a review of the older AP 10" Mak.

 

Here is a quote from that review...

 

"I ran some comparisons with the other telescopes.  The Starmaster 10" EL
matched the Mak on deep sky, but the Dob won't track at high powers like the
Mak will, and the Mak is slightly better on planets.  The AP155 and FCT150
were steadier more of the time on the planets due to their smaller apertures,
but in times of good seeing the Mak put 'em away on low level detail.  On
deep sky the Mak beat the refractors all the time.  The telescope has superb
contrast.  Even the dimmest low contrast galaxies in and around the bowl of
the Big Dipper stood out from the black of the sky."

 

Bob


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#461 Swimmeruk

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Posted 04 September 2019 - 10:21 AM

When my AP shows up I will attempt this comparison.  I have a 12.5 F/5 starmaster that is 20 years old.  I doubt it will keep up.  The primary is needed a re-coating I think.  It has always been a dream to own this scope so I bit at the end of July.  Anyone know how the new ones will compare to the original ?

1, No active cooling but a lighter carbon fiber tube

2.  Dew shield changes

3. I guess a re-designed focuser?  or not  I really cant tell from what I have seen.

Is there anything else?  Has anyone used the sital baader diagonal with it yet?  I have seen it mentioned but the review from 2016 was done with 3 refractors.  I would think that in a reflector it would be less of a difference due to the mirror coatings not being silver based.

-Chad

Indianapolis



#462 Gleason

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Posted 04 September 2019 - 01:49 PM

I own the AP 155 f/7 and the AP 180 f/7 EDF refractors.  The MCT blows them out of the water with sharper and brighter viewing.  No theory, just pure observation across decades of use.  What the MCT can't do is low power. The 155 is superb for that and is hard to beat.   In my observational experience, the MCT comes to temp quicker than either refractor, about 2X faster.  The refractor tubes (aluminum and filled with baffles), love to retain heat and require a good hour for venting with the objective pointed down and the drawtube open.  The older refractors also do not have the benefit of the AP's latest optical anti-reflection coatings.  That would require a restoration.  The star colors in the MCT are more pronounced, with subtle, fine planetary and lunar detail  representative of the 10-inch aperture resolution.  I have been using the Baader silver diagonal.  The Zeiss bioviewer in the MCT has gone beyond anything that I have seen in the refractors. 

 

The MCT idols at 175X with the 21 Ethos, compared to using shorter focal length eyepieces with the refractors.     To be fair, the 155 and 180 are astrograph designs.  They work with big field flatteners for 4x5 or 6x7 format film. And they are amazing with large CCD arrays and with that being said, they have more flexibility than the MCT.  The MCT is a long focus, high resolution, lunar, planetary and multiple star instrument.  Based on what I have viewed of deep sky, the sky background contrast at f/14.5 makes using a 40mm eyepiece quite acceptable. 92X is excellent for most deep sky with a few exceptions on large, extended, low surface brightness nebulae. This combination has proven to be a win over my two refractors showing more contrast and star color. M42 at 175X is amazing in the MCT.      

 

Jump to a larger well made Dob?  Aperture will always win over the small scopes when observing DSO's.  

 

Of course all of this is qualitative and subjective to my own eyes. Your light years may vary. 

 

-jg 


Edited by Gleason, 04 September 2019 - 01:58 PM.

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#463 azure1961p

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Posted 05 September 2019 - 08:55 AM

attachicon.gif AP Mak Panther.jpg

 

I finally got decent seeing without clouds.  Here is the AP Mak on the Panther TTS 160.  The photo angle is unusual, and then I realized that I had to reverse the scope on the mount.

 

There were some vibrations, acceptable to me and my friends but some would not be as happy.  I think this scope is at the upper limit of this mount's capacity.  I am going to try to get a smaller and shorter dovetail which should help things.  Loading and unloading the scope horizontally is a joy.  The mount works beautifully with its step and slew functions.

 

The seeing varied between 3/5 and moments of 4/5, and the temperature dropped 10 degrees in 2 hours.  Initially, I had the back on the scope but after a while I exposed the mirror to the night air.  The scope followed temperature changes fairly well, much better than a big 8-9" refractor but not as well as a 4-5" refractor..The night was not good enough at mid to lower altitudes to allow high enough powers to really test the scope, but Jupiter and Saturn had moments of great clarity at 167x.  I did an abbreviated star test at 295x near the zenith and saw similar patterns to the Maksutov images in the second edition of Suiter.  The Maks have some high order balanced spherical aberration that detracts little from the Strehl but causes asymmetry in the test, and that mixed with less than perfect seeing and some thermals made it more difficult to interpret.  In the first version of the Mak, Roland spent a long time aspherizing some of the surfaces because he was afraid of what the star testers would say, but it made no difference at the interferometer.  Here is an ancient post and thread that discussed these things (unmoderated discussions have huge flame wars but are interesting at times).  Note that this was before the second edition of Suiter came out, and I am sure the chapter in the second edition was in part inspired by this discussion.  I am mainly posting this so people who see an asymmetric star test don't freak out.

 

https://groups.googl...04/cDZl3wbrjb8J

 

In any case, I'm going to concentrate on in focus images with this scope but I will need to wait for next year spring for good planet seeing.

 

Derek

 

PS The mechanics of this scope are amazing, as they should be!

Well ok then!

 

Nice star tests !!

 

So are we going to see your reports, images or drawings in the appropriate forums?  I love it when folks get great glass but then u never hear from them again.

 

Pete



#464 Gleason

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Posted 05 September 2019 - 11:51 AM

Pete, there are numerous observing reports, photos, etchings, drawings, lab tests, and white papers, posted in the exclusive, owners only, secret handshake and password protected MCT Bortle Zero forum.  lol.gif  


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#465 Derek Wong

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Posted 05 September 2019 - 04:06 PM

Well ok then!

 

Nice star tests !!

 

So are we going to see your reports, images or drawings in the appropriate forums?  I love it when folks get great glass but then u never hear from them again.

 

Pete

Hi Pete:

 

I can't draw (my art is worse than a kindergarten student, no joke) and my job is so busy that I am no longer active in these forums or any other forums.  I will try the scope out against 8-9" refractors but only when the planets are higher with stable seeing, likely late spring next year.  I won't use the scope much for deep sky because I live near Los Angeles and I bring a Dob to the sites.  The most likely observing will be to transport the scope to Mt. Wilson when the seeing gets really good.  I'll try to post something but no guarantees, sorry.

 

Derek


Edited by Derek Wong, 05 September 2019 - 04:06 PM.


#466 Asbytec

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Posted 05 September 2019 - 08:25 PM

The curious, biting question is, these are arguably some of the finest handcrafted scopes in the 10" aperture class, they should put up an essentially perfect image. If not a perfect diffracted image. So, yea, a nice description of Jupiter, for those of us familiar with it, can tell us something about what you see in such a fine instrument. We all want to know what a perfect image of Jove looks like. Maybe a galaxy, etc. 

 

MCTs are sexy scopes, even mine is kind of cute. That large deeply curved meniscus drives a basic survival stimulus in our primitive brain parts. But, the meat and potatoes is the image is delivers. I tried sneaking into the Bortle 0 forum fumbling through my collection of secret handshakes and was promptly booted for being a poser. :)


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#467 Gleason

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Posted 06 September 2019 - 11:46 AM

The curious, biting question is, these are arguably some of the finest handcrafted scopes in the 10" aperture class, they should put up an essentially perfect image. If not a perfect diffracted image. So, yea, a nice description of Jupiter, for those of us familiar with it, can tell us something about what you see in such a fine instrument. We all want to know what a perfect image of Jove looks like. Maybe a galaxy, etc. 

 

MCTs are sexy scopes, even mine is kind of cute. That large deeply curved meniscus drives a basic survival stimulus in our primitive brain parts. But, the meat and potatoes is the image is delivers. I tried sneaking into the Bortle 0 forum fumbling through my collection of secret handshakes and was promptly booted for being a poser. smile.gif

Yes, but atmospheric seeing, and other environmental influences are factors that degrades perfection.  Because I live in the Northern hemisphere, Jupiter and Saturn observing have not been optimal due to the low declination passage across my local meridian.  From my May/June notes on Jupiter: 

 

- No surface shadings visible on any of the Jovian moons although they are large, round disks.  6mm and 10mm Delos.  

- Faint shading within the Great Red Spot. Darker edge seen around circumference the Red Spot. 10mm Delos

- Fine polar shading, occasionally broken into faint bands. 10mm Delos

- Blue-gray festoons always visible with faint shading along the trailing edges 

- Numerous white ovals and cigar-shaped dark clouds between the equatorial bands. 

- The main broad equatorial bands are red/brown, and exhibit fine structure in moments of air steadiness. 

- Planet colors and bands matching the most recent Hubble images, but lower color saturation. 

 

Saturn:

 

Spectacular views in the 10 Delos when seeing has supported it. I have yet to crack the Encke minima at any magnification. Seeing has just not cooperated.   Rings are well defined, shaded, the Cassini gap is black and wide.

 

This brings me back to an original point.  External thermal sources, eyepiece types, atmospheric seeing, the physical attributes and health of the observer's eye all play a role in what can been seen in this telescope, or any telescope.  The true quantification of perfection will only come from an optical bench test in a controlled environment.  


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#468 Asbytec

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Posted 06 September 2019 - 12:44 PM

Gleason, thank you.

 

Your description actually brings out the importance of environmental conditions. I stumbled into a retirement location with fine tropical observing conditions conducive to thermal stability and great seeing. Along with that comes very precise collimation. And of course you're describing Jupiter, the benchmark. smile.gif

 

- Here we get some surface albedo on Ganymede when those features are well placed in it's orbit. My guess is you've seen this, as well, in much better scopes. It does require very good seeing. 

- Yea, sometimes I get some faint shading in the GRS, sometimes not. 

- Polar regions are normally a mix of banding and sometimes blotches. Larger blotches, not the smaller ones. 

- Yes, festoons. Pale blue, anyway. Maybe some grey, but I see mostly pale blue. They come and go with the seeing. 

- I'm glad you mentioned white ovals, those are kind of tough. I might briefly catch one or two at a time, and over time have seen about half of them. 

- Yep, same here. The belts do have some detail within them. 

- At my smaller aperture, color is not far from grey scale. But, learning to spot soft hues is key to seeing detail. 

 

But, here's the kicker. This is what you see in lesser seeing, yes? For me, it takes great seeing and some effort to eek out that level of detail. It's kind of your point. I can only imagine the what increased aperture and higher quality can do under the same conditions. Below is a cherry pick of one of my better observations. It's embellished (hue and contrast) so others do not have to work as hard to see it. It only contains the resolution of a 6" aperture, not the increased resolution of a 10". I am absolutely certain, given the chance, the 10" MCT can do so much better. It has to, and so can a 6" APO. It does depend on the seeing, thermal stability, collimation, and the acuity of the observer. Below is giving it all I got in the best seeing I've known. 

 

Jupiter 22 Dec 1600UT draft.png

 

You mention Saturn, too. Here's one I want to attempt to make Saturn all that more exciting. The multi toned B ring has a brighter edge bordering the Cassini division. But, that brighter edge actually has a really a low contrast white ring embedded within it. I have not seen that low contrast feature, but maybe with some eyepiece time and some steady seeing. It may just be a feature reserved for larger aperture, no idea. A few years ago at our latitude, Saturn crossed near the zenith in Pickering 8/10 or better. Under those conditions, and to your point, Enke minimum is pretty easy under those conditions. But, not otherwise. The A ring has a brighter ringlet bordering Cassini division, too. This year, so far, I have not seen either feature even though Saturn is about 25 degrees max elevation. Saturn's equatorial bands are easy enough, but the temperate zones are extremely difficult. No hex, just a small dark polar cap. Seeing is just not as good in the monsoon season as the unstable weather drives up from the south, but a few years ago it was high in the sky during our dry season. 

 

Yes, you're correct about observing conditions and the observer. I often imagined some nights here in the tropics, not unlike the Winter Star Party, are about as close to lab conditions in the field as one might get. So, yea, any scope performs at it's best, whatever that best is. Back in 2012 watching Mars approach and it's north polar cap going through changes, I could actually see brighter portions of the cap and even one (very large, but tiny in the eyepiece) fissure that formed. Such is the power of the atmosphere to either allow or deny us the pleasure. In the tropics, diurnal temperatures are modest and fairly steady and great seeing is not a once in a life time thing.

 

All of this is why I (we) understand no image is more pristine than an one formed by a premium optic, fine machined parts, great stray light control, and the rest. But, the 'diffraction limit' is nothing to sneeze at, either, when given half a chance to perform to that level. Bottom line for me, no matter the scope, the pedigree, the cost, or anything else...the best scopes get used because they are pleasing to use. Just like mine does for me, and just like yours does for you, et al. (Well, your might be more fun to use given the chance. lol.gif

 

Edit: But in the end, I found what I enjoy most is the favorable observing climate. Absolutely. Nights when you take a moment to thank the God of your choosing for such wonderful sights. 


Edited by Asbytec, 06 September 2019 - 01:37 PM.

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#469 Paul Hyndman

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Posted 06 September 2019 - 03:02 PM

Having seen Chris Go’s work and now reading your account makes me think perhaps it’s time to consider relocating ! (Nah, I’d miss my wife... she’d never assent to leaving the grand kids behind). shocked.gif

 

As with other AP Mak-Cass owners here, I find myself hampered by schedule and weather. Alas, not the worst dilemma to have, but frustrating nonetheless.



#470 Asbytec

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Posted 06 September 2019 - 03:31 PM

As with other AP Mak-Cass owners here, I find myself hampered by schedule and weather. Alas, not the worst dilemma to have, but frustrating nonetheless.

And us as well. I am just getting familiar with my 8" f/6 Dob, but the monsoon kicked in fully a month ago and we have several months to wait before it clears. If we're lucky. You know, there is a tropical jet stream, too, but it does not seem to bother us for some reason. Not really sure where it is, probably north of us by 15 degrees latitude or so. But, the "tropical depression" really set in this time of year. I feel ya. A good dry season is just the opposite, though, most every night is clear. Transparency suffers a little, but seeing is normally good with the air-mass coming off thousands of miles of Pacific ocean. But, for now, the summer milky way is obscured. We don't get to see it all that often, it's pretty much gone by November. Then there is La Nina. Seems we're all waiting on the planets, too. 



#471 Swimmeruk

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Posted 14 September 2019 - 05:24 PM

Anyone hear any updates on the second wave's shipment scheduled?



#472 Gleason

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Posted 19 September 2019 - 07:19 PM

Anyone hear any updates on the second wave's shipment scheduled?

I thought the 2nd wave had already shipped.  Have you been notified? 



#473 Swimmeruk

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Posted 19 September 2019 - 08:48 PM

Yeah ... july...i said yes.
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#474 Swimmeruk

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Posted 19 September 2019 - 08:49 PM

Wait list since 1999
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#475 Gleason

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Posted 20 September 2019 - 06:01 PM

Wait list since 1999

At some point you will get the email or letter to send your $11,000 deposit.  Then count on waiting a bit longer after that.  They usually won't take the deposit unless they are working on them.  The latest run of Stowaways and Mach 2's are probably priority right now.  If you got the call and said yes, you're 30% there. ;-)




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