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10" Newtonian on Atlas EQ-G

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#1 RatBiscuit225

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Posted 01 December 2012 - 06:11 PM

Hello,
I'm not quite sure if this is where this post belongs...
I am looking at Orion's 10" f/3.9 Newtonian as my next telescope. It's 25 lbs, and the Atlas has a 40 lb weight limit, but I read somewhere that 20 lbs was the sweet spot for the mount, and since I plan to use the scope for photography, I'll be adding a guide scope and a DSLR, I'm not sure if I should be putting a 25 lb scope on the Atlas. The last thing I want to do is damage my mount. Am I safe getting the 10"? Should I downsize and just get the 8" f/3.9 Newtonian instead? I've seen images taken with the Atlas and the 10" Newtonian in Orion's catalog, but that's Orion's catalog, and I don't fully trust a source that wants to sell me something.
Also, any insight you can provide on the advantages and disadvantages of a short focal-length reflector would make my day.
If you want to see the exact scope I'm talking about, here.

#2 rigel123

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Posted 01 December 2012 - 06:47 PM

The mount can handle it, but add the weights of your camera/CCD, guide system, etc and you may be approaching the total limit. You won't hurt the mount but trying to keep everything solid for photography may be a challenge. It is a fast scope so you may be able to get away with some shorter subs.

#3 dag55

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Posted 01 December 2012 - 06:51 PM

I would go with the 8" or go to a larger mount like the CGEM DX or a Losmandy G-ii in order to have the stability you wil need. Cheaper to go a little heavy on the mount than to get one and find out you need to upgrade.Dane

#4 jgraham

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Posted 01 December 2012 - 06:55 PM

The Atlas can handle the weight, but if'n it were me I'd go with the 8". A 10" is getting a bit big for imaging.

Visual... big scope on an adequate mount.

Imaging... small to modest scope on a solid mount.

#5 Dan Watt

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Posted 01 December 2012 - 06:58 PM

I use an Atlas with a 8" f4, DSLR, 80mm Stellarvue Nighthawk for guiding and I have zero problems with that setup, even in a light breeze. I can take 10 minute photos all night long without having to throw out a single one. I think you'll find with some reading that the newer Atlas mounts can go a lot higher than 20 lbs for an imaging load.

I think you'll be okay with the 10" but I really think you should consider the 8" f4, you'll be plenty happy with it and it will be a bit easier of a load. The 10" will be much bigger than you imagine once you open the box and put it up on the mount.

#6 David Pavlich

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Posted 01 December 2012 - 10:55 PM

Ayup...go with the 8". Your Atlas will be much happier.

David

#7 Raginar

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Posted 02 December 2012 - 01:16 AM

+1 for the 8". Less is more.

#8 RatBiscuit225

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Posted 02 December 2012 - 09:21 AM

So considering I already have a 5.1" f/5 reflector, would the 8" one make enough difference to be worth $500, in terms of both astrophotography and visual use?

#9 Jb32828

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Posted 02 December 2012 - 11:33 AM

Oh you will definitely see a difference between the 5.1 and the 8 inch. i got to test using my 6" and an 8" side by side and for AP even that 2" jump is a big deal in terms of light gathering capability for a camera, and I will be upgrading to the 8" for my Christmas present to myself. Go with the 8"...seriously, you wont believe how big that 10" newt is. That 10" looks huge even on a Losmandy G11 mount...my buddy has that combo and that made me decide that the 8" is gonna be my limit. I have no desire to heft around that kind of weight.

You may also want to consider the Baader MPCC for for visual and AP with an F/4 scope. Although you can crop out the coma at the edge of the field for most wide field stuff, for visual you will want the coma correction and also want it for AP on targets like M31, M42, M45 and the big open clusters and Milky Way stuff.

#10 RatBiscuit225

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Posted 02 December 2012 - 02:09 PM

So the 10" is definitely out; I'll get the 8" and a Baader MPCC. Any other suggestions about things I might need for it?

#11 Mkofski

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Posted 02 December 2012 - 06:47 PM

Post deleted by Mkofski

#12 Dan Watt

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Posted 02 December 2012 - 06:51 PM

I wouldn't go that route, OAG is a bit tougher to implement on a newt because of backfocus, much better off with a regular 50mm guider. Make sure everything is secure (use quality guidescope rings and such) and flexure won't rear it's ugly head.

You will see a huge difference between the 6" and the 8" and imaging at f4 will be a shock. Even going from f5, you will notice the difference.

MPCC or Paracorr is a must.

#13 jgraham

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Posted 02 December 2012 - 09:04 PM

I would never put an off-axis guider on a focuser with a moving draw tube. That's a lot of weight to keep lined up. I use an off-axis guider on my SCT and a guide scope on my SN.

#14 Mkofski

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Posted 02 December 2012 - 09:16 PM

Thanks for pointing out my error! I stand corrected.

#15 dvb

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Posted 02 December 2012 - 11:17 PM

For visual use, I used a 10" f/4.7 Skywatcher/ Orion Newt on my Atlas/ EQ6 Pro.

With accessories, the scope weighed 44 lb., and the Atlas handled it like a champ, but my back was complaining.

The Atlas would have no difficulty handling a 10" Skywatcher Carbon Fibre Quattro (f/4), at about 21 lb., or your scope at 25 lb..

But, as others have said, 10" is an ambitious start for imaging, and most imagers recommend cutting the rated capacity in half for imaging purposes.

If mainly visual, go for the 10"; if mainly imaging, go for the 8".

(I have the the 8" Quattro, which I'm currently using on iOptron iEQ45 and on a Skywatcher AZ4 - it's great.)

#16 David Pavlich

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Posted 03 December 2012 - 09:14 AM

You have to keep in mind that not only the weight of the OTA comes into play, but the size. The least little breeze makes turns it into a sail.

David

#17 RatBiscuit225

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Posted 03 December 2012 - 05:32 PM

So... 30" is the length of the optical tube. Is that big enough for wind to really get in the way? Unfortunately, the scope I have now is much smaller, so I've never dealt with wind... :confused:

#18 David Pavlich

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Posted 03 December 2012 - 10:50 PM

Yes, it does. You'll note that when you get it balanced, the rings are skewed toward the mirror end of the OTA due to the weight of the mirror. So what you'll have is a lot of lever arm sticking out. A breeze catches that big tube and it'll give the mount fits.

David

#19 astro_baby

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Posted 04 December 2012 - 02:20 AM

I had a 10" tube on an EQ6 , same as Atlas, just for visual and I considered it undermounted. Very wobbly even for visual and overly bulky. A pig ro handle and thats why it got sold. Bearing in mind the super tight toerances for imaging I'd guess it would have made things rough for an imager.

#20 dvb

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Posted 04 December 2012 - 02:41 AM

Just so you know it can be done, here is a link to a fellow who has mounted a 10" f/4.7 Skywatcher/ Orion Newtonian on an Atlas/ EQ6, and taken some impressive images:

http://www.skyatnightimages.co.uk

#21 astro_baby

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Posted 04 December 2012 - 02:18 PM

Worth point out though that that link is to Steve Richards site who happens to be very expert, his book is very good by the way.

He has a dome etc where wind may not cause a problem. As said above I found the 10" too wobbly for visual. Might work fine in a dome or in a kinder climate.






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