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TEC 200 Mak vs AP 152 f/8

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#1 Cotts

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Posted 09 January 2013 - 07:46 AM

This will not be one of "those" threads... It seems I have purchased a TEC 200 f/15 Maksutov. It will replace my lovely 1988 AP 6-inch f/8 refractor. The cost of the new scope will be no more than $1000 more than what I can get for the refractor and, if I'm fortunate, maybe only a couple of hundred dollars.

It's win, win, win, I feel. Better colour correction, 2" more aperture, 99% Strehl (I'm sure the refractor is well into 95% territory itself..), less bulky for travel to Star Parties and putting into a small urban observatory like a skyshed pod (the refractor was just too big for that useage).

I'll be cracking doublestars (my favorite), planets and deep sky with the new scope which, if all goes well, will see first light for me at the Winter Star Party.

:grin:

Dave

#2 RAKing

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Posted 09 January 2013 - 08:18 AM

Dave,

Congrats on your scope. I also love my 8 inch Mak (as well as my refractors) and it's a wonderful instrument for splitting tight doubles.

IIRC - you used to have an 8-inch Mak and sold it because of cool down issues. May I ask what changed your mind?

Cheers,

Ron

#3 Eddgie

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Posted 09 January 2013 - 09:16 AM

Win, win, win.. Until you want a dazzling 2 degree true field.

And I expect the AP Strehl was better than .95. My own has optics that appear to be about as perfect as I have seen... I doubt that Mr, Christen would settle for less than near perfection. That is why his wait list is a better part of a decade.

But this has been my own message, and I will repeat it again and again... It is very easy to beat even a perfect 6" refractor on planets and deep sky.

Where big refractors excel was, is, and always will be in the ability to produce very wide, fully illuminated, razor sharp views that are very flat and well corrected for coma.

No one should buy a 6" APO for planets or deep sky. It is far to easy to do better for less money... If you don't need the big field of view.

So, I expect your new scope will do better on deep sky and planets than your 6" APO.

But don't turn it towards the Double Cluster...

#4 Asbytec

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Posted 09 January 2013 - 10:07 AM

Dave, I'd be interested to know how your Mak performs on doubles (your favorite.) I am exploring my own Mak in that arena.

#5 t.r.

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Posted 09 January 2013 - 10:51 AM

Isn't there an advantage for obstructed scopes in splitting doubles due to the secondary and the way the diffraction rings display (energy dispersion)? I'll predict that planetary will be on par...Dave has my seeing conditions!!! :p

#6 Bob Abraham

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Posted 09 January 2013 - 11:42 AM

Dave: I've got an MC200 and a TEC140 and live in the same city as you where I have a POD too. So I've done the 8" Mak vs. 6"-ish apo in a POD comparison from Toronto. Here's what I've found:

1. The MC200 is the better planetary scope, though the TEC140 gives great planetary views too. Both were clearly better than my C8 in side-by-side comparisons (no real surprise) on Jupiter and Mars. Get a binoviewer, which improves the planetary views with both (though with the TEC140 more than with the MC200, for some reason I haven't figured out).

2. The MC200 is a perfect fit for the pod; The TEC140 (5.5" f/7) is also OK in the POD but feeling a tiny bit cramped. A significant benefit of the MC200 is that it can be mounted a bit lower than the TEC140 which gives more zenith clearance with the lip of the pod roof. I suspect you'll still want a POD zenith table some nights though.

3. In general the MC200 is a better double star scope than a TEC140 (though again the latter is no slouch). The 8" aperture is perfect for double stars in our lousy seeing conditions - the airy disk + first ring can be made out nicely (albeit with a broken ring) most nights, and on account of only a 26% obstruction and the great optics in the MC200 if the seeing is at all reasonable you don't get a lot of moving gunk in the PSF from the broken rings so things look rather beautiful in the MC200. I just think it's the right compromise aperture in our seeing for close doubles to look pretty... if you go bigger the seeing limits you most nights, and if you go smaller you're not exploiting all the atmosphere can give you most nights. (For example, I found a C11 lousy for double stars from Toronto because the seeing was usually too poor for a stable airy ring pattern which I find is important for a nice aesthetic view of many close doubles; so even though obviously the C11 would split tighter doubles I liked it far less for doubles than the MC200). The only time the TEC140 is better for doubles is for very unequal pairs for which the secondary lies on the first airy ring.

4. Overall I find the MC200 to be the perfect city double star + planetary scope. But while it's great for use in the city, it wouldn't be my first-choice for a DSO scope; The FoV is too narrow and aperture is too small. The TEC140 solves the former and is more useful for wide-field imaging (and is pretty good at planets and doubles too) so is the more versatile scope.

5. Make sure you're equatorially mounted with the MC200 as you'll be up at 400x for doubles on many nights (particularly during the summer). My favourite eyepiece on the scope is the 8-24mm Baader zoom.

Hope this helps,

Bob

#7 bierbelly

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Posted 09 January 2013 - 11:53 AM

Win, win, win.. Until you want a dazzling 2 degree true field.

And I expect the AP Strehl was better than .95. My own has optics that appear to be about as perfect as I have seen... I doubt that Mr, Christen would settle for less than near perfection. That is why his wait list is a better part of a decade.

But this has been my own message, and I will repeat it again and again... It is very easy to beat even a perfect 6" refractor on planets and deep sky.

Where big refractors excel was, is, and always will be in the ability to produce very wide, fully illuminated, razor sharp views that are very flat and well corrected for coma.

No one should buy a 6" APO for planets or deep sky. It is far to easy to do better for less money... If you don't need the big field of view.

So, I expect your new scope will do better on deep sky and planets than your 6" APO.

But don't turn it towards the Double Cluster...


Funny, I have no problem with the Double Cluster in my Mak... :question: ;)

#8 Eddgie

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Posted 09 January 2013 - 01:02 PM

If you are talking about the scope in your signature line, it is not the same as the f/15 MCT the OP is talking about.

True though, the MNs come very close to the best refractors for all performance.

#9 bierbelly

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Posted 09 January 2013 - 01:21 PM

If you are talking about the scope in your signature line, it is not the same as the f/15 MCT the OP is talking about.


I know. At f/4 it's got a pretty wide FOV. Great for scanning the skies.

#10 doctordub

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Posted 09 January 2013 - 04:47 PM

I have had some excellent views of the double cluster with an f10 IM703 and a Pan 27mm.
CS

#11 Mark Costello

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Posted 09 January 2013 - 05:21 PM

When I observe the double cluster I spend a lot of time at about 118X. The eyepiece I use allows me to frame each cluster separately. I like spending a long time drawing each cluster separately, mapping individual stars and noting the colors in some of the stars.

I also like prolong observations of both clusters framed together. I guess the OP will use his smaller refractors for that....

#12 Cotts

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Posted 09 January 2013 - 06:20 PM

Just to be clear: My AP is not for sale. Don't want any TOS violations....

Dave

#13 Cotts

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Posted 09 January 2013 - 06:22 PM

I don't recall cool-down issues. I sold it to finance my Teeter....

Dave

#14 Cotts

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Posted 09 January 2013 - 06:28 PM

A quick, back of the envelope calculation: My 31 Nagler will yield about 100x. Field of view 0.82 degree.

When I said deep sky I was thinking globs, planetaries, open clusters etc....

Dave

#15 Cotts

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Posted 09 January 2013 - 06:35 PM

Your Mak-Newt is f/4. My new Mak-Cass is f/15.5 - - different beasts entirely.

I have an 80mm (3.1") William Optics Fluorite doublet, f/6.9 which will be the 'finder' as well as a scope that can get all 4 degrees of both halves of the Veil in one view....

Dave

#16 Cotts

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Posted 09 January 2013 - 06:36 PM

I'm picking up the TEC on Saturday and it will get first light at the Winter Star Party so a report will follow...

Hang in there.....

Dave

#17 Cotts

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Posted 09 January 2013 - 06:41 PM

Hi, Bob. I met you at an NYAA meeting, yes? Anyway, thanks for the input. I'm most happy about the possibility of a Pod now. The TEC 200 will fit in there nicely with my rather hefty bulk - 6'6" - the AP didn't have a chance....

The mount is an AP Mach 1 so no difficulties there....

Dav

#18 doug mc

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Posted 09 January 2013 - 07:10 PM

A question about double star observing with scopes with central obstructions? Seeing that the mak is bigger than the refractor does a nd filter reduce the diffraction ring brightness to a point where it helps seeing stars on the first diffraction ring. Dollar for dollar one can get much bigger maks than refractors, so some light loss to should not be a major problem. The nd filter does not interfere with cromatic correction. True or false?

#19 Bob Abraham

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Posted 09 January 2013 - 08:31 PM

With an ND filter the contrast ratio (the main factor) will be unchanged. So I am pretty sure it won't help. Some sort of apodizing mask (a spatial filter in Fourier space) could help in principle though the resulting PSF will be ugly.

Bob

#20 Bob Abraham

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Posted 09 January 2013 - 08:44 PM

Hi Dave,

We probably met at Starfest a couple of years ago when the NYAA invited me up to give a talk.

If you're 6' 6" you've got 8" of height on me but I'm pretty confident you won't be too squeezed in a POD, as the relevant squeeze point tends to be round the midsection (and sadly I've probably got you matched there!).

I've got a Mach-1 too and if you really want a roomy POD with your MC200 then you may wish to get a "shorty" counterweight bar if you haven't already got one. It really helps free up some room round the front of the scope which helps a lot.

I think you'll love your new scope...

Bob

Hi, Bob. I met you at an NYAA meeting, yes? Anyway, thanks for the input. I'm most happy about the possibility of a Pod now. The TEC 200 will fit in there nicely with my rather hefty bulk - 6'6" - the AP didn't have a chance....

The mount is an AP Mach 1 so no difficulties there....

Dav



#21 vahe

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Posted 09 January 2013 - 08:56 PM

I'm picking up the TEC on Saturday and it will get first light at the Winter Star Party so a report will follow...



If this TEC 200 Mak is the one on Amart I would really appreciate if you can give me the make and model of the case that comes with the scope.
I also have a TEC 200 Mak and definitely love to have that case.

Vahe

#22 gatorengineer

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Posted 09 January 2013 - 09:10 PM

Beautiful scope, I am sure you will enjoy it. And the 29 Arc Minute Double cluster will fit very nicely in it :waytogo:

#23 maknewtnut

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Posted 09 January 2013 - 09:55 PM

I've had the need to scratch my Mak itch lately as well DC.
I think you'll enjoy the TEC, and be able to get the most out of it if observatory housed. Don't be alarmed if the focuser might have become disengaged during shipment(likely rare, but it has happened to others). It's an easy fix for you or Yuri.

Managed to pick up a super rare LOMO 203 MCT a couple of years ago. A quick analysis indicated it could never have been collimated because one primary collimation screw required replacement with a longer one to even line up the baffle to the secondary...then never really used it(apparently wasn't itching that hard back then).

Pulled it out and disassembled a couple of weeks ago to consider the possibility of cooling upgrades. Found the full length baffle tube cocked sideways. Clean, polish, reattach, relube, (and reinstall the factory collimation screw) etc....and the thing really rocks! IIRC the history page from TEC's website correctly, it was LOMO that Yuri did some of his first work with in the US. Both LOMO and TEC are pretty darn good bets on superb optics (and a bit in common when it comes to design cues too).

Split the Trap at med mag under Pickering 5-6 skies....yours will too. Enjoy!

#24 Cotts

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Posted 09 January 2013 - 10:03 PM

I'm picking up the TEC on Saturday and it will get first light at the Winter Star Party so a report will follow...





If this TEC 200 Mak is the one on Amart I would really appreciate if you can give me the make and model of the case that comes with the scope.
I also have a TEC 200 Mak and definitely love to have that case.

Vahe


I'll have the scope and case (yes, the ones on AMrt) back here in Toronto by Saturday night. I'll send the info then....

Dave

#25 Bob Abraham

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Posted 09 January 2013 - 10:49 PM

Mark: please post some pictures of that LOMO it would be fun to see it! Does it have an integrated fork mount or is it an OTA?

Dave: I know what Mark is talking about because my focuser did become disengaged once after shipment. If it ever happens its a trivial fix that Yuri emailed me how to do and it takes 10 mins max.

Bob

PS Some colleagues of mine visited LOMO a few years ago as they're one of the few companies capable of handling the fabrication of the Thirty Meter Telescope's mirror segments (mass production is needed, basically). I was told their huge facility resembles a car factory. They are such a big industrial outfit I'm a little surprised they do optics for the small amateur astronomy market too.

I've had the need to scratch my Mak itch lately as well DC.
I think you'll enjoy the TEC, and be able to get the most out of it if observatory housed. Don't be alarmed if the focuser might have become disengaged during shipment(likely rare, but it has happened to others). It's an easy fix for you or Yuri.

Managed to pick up a super rare LOMO 203 MCT a couple of years ago. A quick analysis indicated it could never have been collimated because one primary collimation screw required replacement with a longer one to even line up the baffle to the secondary...then never really used it(apparently wasn't itching that hard back then).

Pulled it out and disassembled a couple of weeks ago to consider the possibility of cooling upgrades. Found the full length baffle tube cocked sideways. Clean, polish, reattach, relube, (and reinstall the factory collimation screw) etc....and the thing really rocks! IIRC the history page from TEC's website correctly, it was LOMO that Yuri did some of his first work with in the US. Both LOMO and TEC are pretty darn good bets on superb optics (and a bit in common when it comes to design cues too).

Split the Trap at med mag under Pickering 5-6 skies....yours will too. Enjoy!








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