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Astrotech AT72EDII

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#1 kyle528

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Posted 21 March 2019 - 02:45 PM

I am very seriously considering this as my first scope. It's pretty well fit for my budget, and it seems to have great reviews. Anyone here have experience with one? Note that my setup is (for the time being) with an unmodified dslr, and a star adventurer. I know that my mount/camera situation is not ideal, but that's just how it is for now. That being said, I have acquired decent images with the assortment of lenses I have access to, however I will not have this access much longer. I've shot most of my images at 200mm, this scope is 430. Will that have a dramatic effect on sub exposure times given I'm using an unguided star adventurer? I expect it to be noticeable, but with very careful balance and PA, should I still expect to manage subs to at least 1 minute? I've heard of success guiding the star adventurer, even if it is only guided in right ascension. At this point, I'm between this scope and the WO Z61, but this is 10mm more for essentially the same price. From any users of this scope, how is coma and CA? Those are my two main concerns buying a doublet. 



#2 Dwight J

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Posted 21 March 2019 - 04:19 PM

I have the earlier version.  If thenew one’s optics are the same or similar, you will need a field flattener.  I use the Orion/Hotech 0.8X one which puts the scope at F4.8/ 335 mm FL.  Frames big stuff like M31 and M45 really well.  Rotatable focuser is handy too.  I would buy it again.



#3 bobzeq25

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Posted 21 March 2019 - 04:32 PM

I am very seriously considering this as my first scope. It's pretty well fit for my budget, and it seems to have great reviews. Anyone here have experience with one? Note that my setup is (for the time being) with an unmodified dslr, and a star adventurer. I know that my mount/camera situation is not ideal, but that's just how it is for now. That being said, I have acquired decent images with the assortment of lenses I have access to, however I will not have this access much longer. I've shot most of my images at 200mm, this scope is 430. Will that have a dramatic effect on sub exposure times given I'm using an unguided star adventurer? I expect it to be noticeable, but with very careful balance and PA, should I still expect to manage subs to at least 1 minute? I've heard of success guiding the star adventurer, even if it is only guided in right ascension. At this point, I'm between this scope and the WO Z61, but this is 10mm more for essentially the same price. From any users of this scope, how is coma and CA? Those are my two main concerns buying a doublet. 

You're doing a typical beginner thing, trying to squeak by with a marginal mount.  That can work, or it can be a path to frustration and wasted time.

 

I'd go with the lighter shorter 61.  That has to be a better idea.  Here's a review.

 

https://astrobackyar...star-61-review/

 

Whatever the longest exposure you've done with the 200, cut it by a bit more than half for a 430.  It's pretty much a linear relationship.  Plus the weight factor.


Edited by bobzeq25, 21 March 2019 - 04:37 PM.


#4 kyle528

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Posted 21 March 2019 - 04:37 PM

You're doing a typical beginner thing, trying to squeak by with a marginal mount.  That can work, or it can be a path to frustration and wasted time.

 

I'd go with the lighter shorter 61.  That has to be a better idea.

 

Whatever the longest exposure you've done with the 200, cut it by a bit more than half for a 430.  It's pretty much a linear relationship.  Plus the weight factor.

I realize my mount isn't even close to ideal for DSO imaging, but I simply can't help it for the time being. I have had access to high end lenses since I started imaging a little over a month ago, but a move in the near future will discontinue that. I figure if I have to choose between a scope on a marginal mount or a good mount with a 55mm kit lens trying to shoot DSOs, I'd rather make do with the scope and upgrading the mount is next on my list, believe me. I have done a lot of research and I am well aware of the inadequate mount beginner mistake, and I am trying to avoid that the best I can, even though I am sort of in that situation already. I plan on having an eq6-r or similar by fall, do you think making do with the AT72 will be a better long term investment? A 0.8x FF/FR knocks me down to 344mm f4.8, which isn't a huge jump from the 200/250mm I can get 2 mins on currently


Edited by kyle528, 21 March 2019 - 04:42 PM.

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#5 bobzeq25

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Posted 21 March 2019 - 10:22 PM

I realize my mount isn't even close to ideal for DSO imaging, but I simply can't help it for the time being. I have had access to high end lenses since I started imaging a little over a month ago, but a move in the near future will discontinue that. I figure if I have to choose between a scope on a marginal mount or a good mount with a 55mm kit lens trying to shoot DSOs, I'd rather make do with the scope and upgrading the mount is next on my list, believe me. I have done a lot of research and I am well aware of the inadequate mount beginner mistake, and I am trying to avoid that the best I can, even though I am sort of in that situation already. I plan on having an eq6-r or similar by fall, do you think making do with the AT72 will be a better long term investment? A 0.8x FF/FR knocks me down to 344mm f4.8, which isn't a huge jump from the 200/250mm I can get 2 mins on currently

It's tricky.  "Making do" may slow your progress, while you mess around trying to make the Star Adventurer do something it's not designed to do.  The reducer helps, but there's still the weight.

 

The alternative is to get a new $150 50mm fixed focal length camera lens, and continue to learn the techniques.  Or a used 200mm.  Fixed focal lengths are better than zooms. 

 

Or the 61.

 

It's just a personal choice.  I'm always going to prioritize learning imaging over imaging, when advising a beginner.  I recognize the beginners priorities are likely the reverse.

 

Just know that I'm not at all concerned with your images, not at all concerned with what the "ideal setup for imaging" is.  Just what's better for learning imaging.  That's why I recommended the 61.  The Star Adventurer could maybe handle that.  It could maybe handle the 72.  At that price point, quality control is pretty poor, and there are good ones and not so good ones.

 

Idea.  Try the 72.  If it works OK, fine.  But if you're spending a lot of time trying to make it work, consider dropping back to a camera lens until you can get the mount.  Spending time instead on things like getting better flats.  <smile>


Edited by bobzeq25, 21 March 2019 - 10:23 PM.

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#6 james7ca

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Posted 22 March 2019 - 08:19 AM

I have the earlier version of the AT72ED and I think you will be happy with your purchase. Bang for the buck, it's turned out to be one of the best purchases that I've made in astronomy (for both visual and photographically).

 

That said, don't expect perfect color correction nor flat-to-the-edge images even with the 0.8X reducer/corrector.



#7 Peregrinatum

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Posted 22 March 2019 - 12:39 PM

I am looking at this one myself, it is supposed to have very good glass with the FPL-53 ED in a doublet... hard to beat the price as well!




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