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astrotech 72 vs long focus 76 mm

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#1 Jim_Smith

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Posted 26 January 2013 - 01:50 PM

How these two scopes compare on planets double stars and planets? Would the long focal ratioa make the 76 superior? Thanks jim ( taking into account 4 mm.larger apeture?? Thanks jim :confused:

#2 Jim_Smith

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Posted 26 January 2013 - 02:37 PM

The cost of the classic is $ 300 ..COPARED se mount?? THANKS JIM..+i i have

#3 terraclarke

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Posted 26 January 2013 - 03:13 PM

I have the AT72ED and I really like it. It is such a very capable scope for its size. I love the wide field views and its nice for quick views of the planets, sun in white light,etc. it is a quintessential grab and go, and is also airline portable. I can not say the same thing about my long focus scopes. With regard to it being optically an equal, I can equivocally state that again, it is not. Compared to my more than 40 year old 76 mm F16 Sears Model 6344 or my Unitrons it is no where near the same when viewing Jupiter, Saturn, Mars, the Moon, or the Sun. There is nothing that can beat a really good f15 or higher long focus achromat, inch for inch of aperture. Then again, there is something to be said for expediency. You be the judge.

#4 Jim_Smith

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Posted 26 January 2013 - 04:27 PM

Thank you!! One ($300) long focus 76 the othrr $379....with my celestron se mount would i i enjoy its performance.n? Expecting sharp refractor views? Darnit. Decisions desions.thanksnn.jim

#5 Jon Isaacs

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Posted 26 January 2013 - 08:07 PM

Thank you!! One ($300) long focus 76 the othrr $379....with my celestron se mount would i i enjoy its performance.n? Expecting sharp refractor views? Darnit. Decisions desions.thanksnn.jim


I would go for an ED-80. Better glass, still very compact and easy to mount. My experience is that an 80mm F/7 FPL-53 doublet is hard to beat in it's class as a planetary scope.

Jon

#6 KWB

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Posted 26 January 2013 - 09:42 PM

Thank you!! One ($300) long focus 76 the othrr $379....with my celestron se mount would i i enjoy its performance.n? Expecting sharp refractor views? Darnit. Decisions desions.thanksnn.jim


I would go for an ED-80. Better glass, still very compact and easy to mount. My experience is that an 80mm F/7 FPL-53 doublet is hard to beat in it's class as a planetary scope.

Jon

:ubetcha: :waytogo:

#7 mikey cee

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Posted 26 January 2013 - 10:36 PM

For my :penny: :penny: I'd bet that there isn't a nickel's worth of difference between the two. But I just like oldies better that's all. :smirk: Mike

#8 Jon Isaacs

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Posted 27 January 2013 - 04:52 AM

For my :penny: :penny: I'd bet that there isn't a nickel's worth of difference between the two. But I just like oldies better that's all. :smirk: Mike


I have owned a few 76mm F/16's, currently own a three 80mm F/11s. My 80mm F/7 William Optics FD is better than the F/11's. The 76mm F/16's are just so darn awkward for such a small scope, I use them one night and then give them away... If I want that old time feel, I go for the 60mm F/13.3 A-P. It's got a rock solid mount, something few old scopes do, and compact enough that it's not a gymnastic's medal performance just to get near the eyepiece. :)

Jon Isaacs

#9 Rutilus

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Posted 27 January 2013 - 05:14 AM

Here,s two drawing (year 2009) I made 5 days apart, one with a modern 80mm ED with multi-coatings,
and the other with my 47 year old 76mm f/16 Achromat with single coating of MgF2.


The drawing on the right was made in slightly better seeing conditions.

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#10 terraclarke

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Posted 27 January 2013 - 12:35 PM

Again, I was comparing my 72 F6 to my 76 and 75 F 16s. And I was directly answering the question that was asked at the threads beginning. On a good night the AT72ED can take 160X. My 60 mm Unitron can beat it easily on planets. The 75mm and 76mm can easily do 240X and on occasion 300X. Granted, they are a little bit cumbersome but they have very good mounts. The AT72 is a good little scope and lots of fun, but show me the AT72 or its WO equivalent that can equal or beat a 3 inch Unitron or other fine old equivalent Japanese long focus objective. There ain't enough tea or objectives in China to make me believe that.

#11 Stan the man

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Posted 27 January 2013 - 02:17 PM

I have the AT72ED and I really like it. It is such a very capable scope for its size. I love the wide field views and its nice for quick views of the planets, sun in white light,etc. it is a quintessential grab and go, and is also airline portable. I can not say the same thing about my long focus scopes. With regard to it being optically an equal, I can equivocally state that again, it is not. Compared to my more than 40 year old 76 mm F16 Sears Model 6344 or my Unitrons it is no where near the same when viewing Jupiter, Saturn, Mars, the Moon, or the Sun. There is nothing that can beat a really good f15 or higher long focus achromat, inch for inch of aperture. Then again, there is something to be said for expediency. You be the judge.


I agree too. I had one of them 72eds and compared it to a classic 3" f/15. No contest! 72ed long gone.

Stan.

#12 Bongo123

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Posted 27 January 2013 - 04:28 PM

Well my opinion is, the longer F ratios are more forgiving of optical faults in both the glass and the eye using the glass. That's just my opinion.

Yes I agree, both scopes have their place, and I'm not selling ether one.

#13 jrbarnett

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Posted 27 January 2013 - 08:08 PM

Agree.

The AT72ED is fine for wide field, low power, but it can't handle magnification for squat.

I have a Royal Astro 76.2mm and an FS-78, and both of these obliterate the AT72ED in terms of handling magnification without image breakdown. I now have three AT scopes - an AT111EDT, AT60EDT and AT72ED. Only the AT111EDT has excellent optics. It's not a fast-slow scope thing, or achromat-apochromat thing. It's an optical quality thing.

Better quality optics, fast or slow, handle magnification better. I've seen my share of poor quality slow scopes too. There's no magic in focal ratio that isn't trumped by better optical quality.

A great quality AT72ED will best a low quality 3" long focus achro, and there are plenty of those around. However, I suspect that the AT72ED is built to a price and really excellent ones, while they exist I'm sure, aren't that common. These 76.2mm long focus achros were EXPENSIVE scopes in their day. I suspect that more often than not a good amount of care was put into the optics due to the maker having ample margin with which to make such an investment and still turn a profit.

Regards,

Jim






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