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BEYOND EARTH

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BEYOND EARTH

BEYOND EARTH

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I've been in the market for a new setup for about a year now, and after months of research I've narrowed it down to two. This is where I could use all the help I can get. The first scope is a NexStar 8SE Computerized Telescope and the second is the C8-SGT (XLT) Computerized Telescope. Now what I would like to know is which is better for astrophotography, they both have the same specs? I would think the C8-SGT (XLT) would be better due to the fact that you can change the optical tube to a better one. I really just don't know... if I could get some feed back that would be great.

Thank You!

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Nexus 6

Nexus 6

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yup, the 8se is a decent scope but is not really cut out for astro imaging dso's as its on an alt/az mount so the other option is your best bet.

Am sure others will agree, having said that if its for solar system imaging using a web cam you can still get some pretty good results.

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ollypenrice

ollypenrice

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OK, at the risk of courting unpopularity I'm going to say 'neither' if, by astrophotography, you mean deep sky imaging. An 8 inch SCT has a slow focal ratio which means very long exposures. F5 is four times faster tha F10. This puts pressure on the guiding ability of your mount since it has to track with precision for longer.

The scope also has a long focal length and, the longer the focal length, the more accurate the tracking has to be. Even with focal reducer-flattener the focal length is still quite demanding. Long FL and slow FR = double whammy.

All this points squarely towards the golden rule of imaging, which is mount comes first. It has to be equatorial, it has to have the tracking accuracy required by the focal length and it has to have more than enough payload capacity for scope, camera, guidescope and autoguide camera. Most of the time you should ensure the payload is half to two thirds of the manufacturers claims, though the really premium mount makers are more honest.

The XLT would be badly under mounted and very unlikely to deliver the necessary tracking accuracy under autoguiding.

The SE is an altazimuth mount as standard and therefore cannot be used for deep sky imaging. (OK you could take 30 second subs but at F10 they wouldn't have much on them!!) So it would need an equatorial wedge, and not many people in imaging are in love with these. They are hard to polar align and make the all important balancing of the rig more difficult as well. I wouldn't touch them again, myself, having tried once.

If you are dead set on an 8 inch SCT you need an NEQ6, the Celestron variant or an iOptron IEQ45. Assuming you focally reduce to F6.3 (and you'd need to in order to get anything like a flat field and even ilumination) these mounts, with an autoguider, should give you a workable platform for imaging.

If I were setting out on DS imaging I'd be looking at somethiing like this http://www.firstlightoptics.com/pro-series/skywatcher-evostar-80ed-ds-pro-outfit.html along with an ST80 guidescope. In this kind of rig you have more mount that scope and that's how I like it. Have a look at the DS imaging board to see what folks are using and maybe read Steve's book Making every photon count, also from FLO.

Olly

http://ollypenrice.smugmug.com/

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BEYOND EARTH

BEYOND EARTH

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Olly you just blow my mind.. what you just said was very helpful. Now the only problem I see is well I only have around $2,000 to play with, and the Sky-Watcher Pro 120ED APO with CGEM Mount is just shy of $3,000. Could you recommend a decent setup for around $2,000?

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ollypenrice

ollypenrice

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Olly you just blow my mind.. what you just said was very helpful. Now the only problem I see is well I only have around $2,000 to play with, and the Sky-Watcher Pro 120ED APO with CGEM Mount is just shy of $3,000. Could you recommend a decent setup for around $2,000?

Sorry, did I give you the wrong link? I thought I'd linked to the ED80 from Skywatcher and while that will do fine on an HEQ5, an NEQ6 would allow you to use a bigger scope later.

Honestly, you just don't need a big scope for imaging. There is so much to do at short focal lengths with a small refractor mounted on more that it needs. I sincerely believe that this is the way to success, especially while you are learning. Of course, please ignore me but I took this with a good 85mm refractor on an NEQ6. The ED80 would get extremely close, I believe.

http://ollypenrice.smugmug.com/Other/Nebulae-and-clusters/M42CCBOV2010/1100345185_HHd4m-X3.jpg

Olly

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ollypenrice

ollypenrice

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Small fastish refractor on a good mount is very 'standard issue' advice and many would have given it. I was advised along these lines some years ago by Ian King of Ian King Imaging and I just wish he'd got to me earlier before I'd spent a lot of cash trying to make an LX200 work for me.

Enjoy the adventure. It is exactly that.

Olly

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appalachik

appalachik

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I use the smaller C6 SGT-XLT for imaging, in conjunction with a finder-guider setup (check my signature for a full list of the gear I use). No doubt there are other and better ways to do it, but this works very well IMO. There is a steepish learning curve with imaging and all Olly's comments are correct. I just ended up doing things this way. It also gives me a later option to swap to using my C6 as a guidescope and adding a small fast refractor for the imaging without over-taxing the load capacity of my mount.

I have to have mobility with my setup and it works really well. Here is a link to another C6-SGT astrophotographer...

Kerry's Astrophotography Adventures

Weather and Sky By Kerry - Astrophotography

The results speak for themselves.

Jenna

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