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Astrotech 10" carbon fiber RC


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#1 astrodoc71

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Posted 20 December 2013 - 04:00 AM

After 10 years of imaging with a 40 year old newtonian, and a move to the desert southwest I decided it was time to move on! I am basically a galaxy addict with maybe a few globs and planetaries thrown in. Plus I am very fortunate to have a heavy duty mount, so larger aperture and longer focus is still my thing. What to go with? Unfortunately things like Planewave, Hyperion and the now popular Officina Stellare scopes are way out of my range right now. SCTs I am not a fan of for deep space imaging as the whole system of moving the mirror for focusing causes way too many problems in my opinion. I decided on the Astrotech 10" RC. This is an f/8 scope or 2000mm f.l. This is a popular scope in the US. Produced by Astronomy Technologies, a subsidiary of the company Astronomics, located in Oklahoma, the AT10RC is a Ritchey Chretien optical design which amazingly retails for 3500 US (with the carbon fiber OTA). Obviously this is a fraction of the cost of a Ritchey produced by the RCOS company. It was one of the Hot Products in Sky and Telescope in 2006 and has remained a favorite of the amateur community here in the US.

The scope arrived about a month ago. It did take about 3 months from the time it was ordered as these scopes are generally still on a wait list, but I was expecting longer!

Very well packed and no shipping damage. It is lightweight for it's size, about 25 pounds. The scope comes with a full length dovetail top and bottom, so placing it on the mount was simple. With the camera attached I was able to achieve perfect declination balance by moving the OTA forward a few inches. I conveniently used the top rail for my trusty old Orion ED80. Now this is an astrograph so it's not really designed for visual work as there is a sizable obstruction by the secondary mirror. You can look through it and honestly my eye can't really tell a huge contrast deficit. I mean clusters, nebulae etc still look pretty cool :D

The scope comes with 3 2" ring extenders to reach focus and you will need at least 1 or 2 of these to reach prime focus with your camera. I also went with a Moonlite 2.5" DRO (digital read out) stepper focuser as I am going to try my hand at full automation eventually. Astronomics provides a focuser of their own which I don't know much about. I went with Moonlite because I know what I'm getting. The scope also has an extra slot for a finder if you want to use one. 

Collimation was actually very good out of the box as visually with the Cheshire it really looked spot on. When I went to the star testing which I do using CCDinspector with my SBIG ST8XME, it was about 5 arc sec off. Now the secondary collimation screws turned out to be extremely tight and use a 4mm allen wrench. I had to ask folks about this as I was afraid to force the screws and break something, but it turns out that's how they set the springs in the factory. So I took a deep breath and tweaked the screws and wound up improving the collimation to about 1 arc sec! Astronomics provides a vector diagram which shows you exactly which screws to turn to move the star image in which direction. CCD inspector "collimator viewer" (shown below) produces an arrow which points in the direction you need to move the star. I put the edge of my hand over the objective while taking a series of 3 images and I can easily see where on my scope the arrow corresponds to. So I can fairly easily achieve perfect collimation using this method.

I finally took my first 5 minute test image of the Crab and I think we're in pretty good shape here! Round stars all the way! Now I am using an older camera with a relatively small chip so I'm not taking full advantage of the available FOV, but I think I can live with that for now. Definitely do not need any field flatteners for the time being!

 

Here is the review summary:

 

Excellent:

1)You get a Ritchey Chretien optical system at an amazing price! After all, if it's good enough for NASA, it should be good enough for amateur astro-imaging :P . Not to mention it also comes with a Quartz primary! 

2) Good collimation right out of the box and the potential for basically perfect collimation

3) Dovetail top and bottom

4) Ring extenders provide the flexibility for probably any imaging system

5) Excellent directions provided on collimation and in particular the vector diagram was indispensable for the precision collimation step.

6) Comes with primary fans which are powered by a 12 volt battery pack. 

7) Round stars and flat field

 

Not so excellent:

1) No cautions or warnings about the screws being super tight. It would have saved some time and worry if they told us about that. They could provide you with a torque allen wrench. I had to use a standard allen wrench but needed another wrench to turn it!

2) Balancing of the dec axis is not trivial. Fortunately on my mount, there are several pairs of screws that can anchor the dovetail

on the bottom, but once my camera is hooked up I found that I needed to shift the OTA 3 inches or so forward to balance it and not all mounts will have the capability to provide enough stability with it shifted forward that much

3) Although it is an astrograph, if you want to do visual you will find that you cannot reach focus to do that unless you have an additional extender! In other words, I needed all 3 of the rings provided as well as a 2 inch extension piece I luckily already had!

 

The Ugly:

Well I guess this isn't the end of the world, but seriously, the cover of the OTA is a piece of junk. It's basically a plastic disc that fits on the inside of the OTA rim. There are square pieces of foam that supposedly allow for a stable interference fit, but it's hardly that. If any wind comes along the thing blows right off! So I basically have to tape it on at the end of observing sesions :angry: I do have an all weather cover that I place over the whole rig so it is quite dust proof, but I would say a little disappointing as it isn't exactly a cheap instrument.

 

All in all I think it's a solid investment especially for the price and it should provide very good results for at least a few years  :)

 

AT10RC.jpg

Xmas comes early!

 

set5.jpg

Fully assembled system with ED80 on the top dovetail

 

coll1.jpg

Precision collimation using CCD Inspector. This is actually reading 0.7 arc sec! I think we will stop there!

 

C1.jpg

5 minute raw image of the Crab with a full Moon nearby. Not too bad. Stars look round all the way!

 

And so it's onward and upward!

 

Regards,

Dave


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#2 Neil

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Posted 20 December 2013 - 08:59 AM

Looks very nice indeed Dave,

 

I wish I had a mount like yours... I might just have to settle for painting mine red! :D

 

The scope looks excellent and the collimation perfect. I didn't know that ccd inspector enabled you to collimate your scope? I think all in all you have an excellent setup that will pay dividends, deliveing sharp pin point stars and galaxies. 

 

Regarding the cap, if I were you, I'd measure the outside diameter, cut a 19mm (1/2inch) MDF blank and then hammer some sheet aluminium around it, trim it off, add a bit of velt on the inside and you have a new dust cap for your telescope. I know what to mean though, its a little short sighten to supply such a lovely telescope with a flimsy plastic cap but so long as thats the only short cut they took, I could live with it. Afterall, the important items are the optics and OTA assemble and you have a nice Quartz primary.

 

If you have time, I'd like to hear somemore regarding CCD-Inspector? I've alway thought it was an expenses software package for what it does.

 

Clear Skies

 

 

Neil.



#3 RickS

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Posted 20 December 2013 - 10:37 AM

Nice review, Dave!  Look forward to some images from that scope.

 

Cheers,
Rick.


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#4 astrodoc71

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Posted 20 December 2013 - 01:01 PM

Thanks guys. Yes I agree CCD Inspector isn't the cheapest package around but it is quite versatile and I do use it a lot. 3 features of it that I think make it worthwhile. One is the full width half max monitor that helps determine when you are at the best focus for your seeing conditions. Another is a full analysis of your images which reads among other things, your average FWHM and also aspect ratio to see if in fact you have round stars. Finally is the collimation feature which is great because it not only tells you quantitatively what the collimation accuracy is, but also what to do to adjust it. I figure I am saving in the end by not having to buy a collimation scope  :D

Regards

Dave


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#5 Andromeda

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Posted 21 December 2013 - 01:50 PM

Hi Dave,

Very nice scope and a nive review! I also would like to have a mount like yours!
Succes with your hobby there in New Mexico.

Will

#6 duskchaser

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Posted 21 December 2013 - 07:00 PM

Great review Dave. Looking forward to seeing more images with this scope.

I'm hoping to purchase the 8 inch version in the new year.


Doug.

 

6" Helios Refractor+Monorail focuser+ ST80 Guidescope+Baader guide rings.

Pier mounted NEQ6+EQMOD+Astrotortilla+CDC+Maxim DL 5+'V' filtered SBIG ST 7ME nabg.

Roll off obsy+warm room.

Photometry of Pre-Main Sequence + CV variable stars.