14" vs 8"

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KuriousGeorge avatar
Considering upgrading from an 8" Edge HD to 14" or larger for CCD imaging of galaxies. Can anyone point me to the improvement I might see under similar conditions? My current 8" images are at http://www.astrobin.com/users/KuriousGeorge/
Xplode avatar
Have you thought about a 10-12" f/5 newtonian? It would give you a nice image scale and since it's faster that your current scope would give less noise and much faster results.
Noise seems to be what stops you from getting better results with your current setup and a larger just as slow scope would't help with that.
KuriousGeorge avatar
Thanks. I'll check it out!
Jim Matzger avatar
I got a C11 because I cannot physically lift anything bigger, and I like to regularly reconfigure my setup.  The C11 has many virtues and has enough magnification for most of my more distant targets.  One issue with the SCT in general is mirror shift, which makes consistent focusing almost impossible.  A solution can be found at Optec which makes a device that adjusts the secondary mirror rather than the primary.  With the primary locked in place I do all my focusing with the Optec device.  For imaging you may also want to budget for a 0.7 focal reducer.
PeterT avatar
You don't seem to be doing too badly with that C8 and mount !  Well done.
Hobby Astronomer avatar
You don't seem to be doing too badly with that C8 and mount !  Well done.


I agree. Seems like you are doing well with the C8 and a C14 may be more of a headache than it is worth. I think the 8" is the sweet spot for imaging.

Have a 14 and doubt I will ever use it for imaging.

HA
KuriousGeorge avatar
Thanks guys! Since I posted, I've been gaining more experience with my 8", mount, camera and processing. I think a 14 might yield sharper stars with less donuts after deconvolution (i.e., smaller central obstruction %). But I'm starting to think it might be a very small overall improvement under my seeing conditions, and not worth the extra maintenance a 14 might need (e.g., cleaning, covering, keeping in focus, etc).
Don Curry avatar
I have a C14 classic and would never attempt imaging with it unless you invest in a Astro Physics 1600 Mount. Even then focus shift would be an ongoing problem and guiding would be near impossible at near 4000 mm. I must say although for visual it is a spectacular OTA under extreme dark sky's.
carl0s avatar
I think this is the main issue this t'scope :

Have you thought about a 10-12" f/5 newtonian? It would give you a nice image scale and since it's faster that your current scope would give less noise and much faster results.Noise seems to be what stops you from getting better results with your current setup and a larger just as slow scope would't help with that.

I've been using the 8" Edge myself and it's a great telescope , but it's slow. I'll keep it, because it is portable and I really like the Edge+Hyperstar combination. At longer focal lengths, the light gathering power isn't that good. I was considering a Newton because of it's FL and speed but was able to get a bargain RC10. Like the Edge , the RC10 also has a corrected field but it has more light collecting power. Clear nights are rare here, hence speed and aperture are important for me.

Again, it's a good telescope. And there are people , who really know how to use it properly: e.g  http://www.astrobin.com/users/Thirteen/
KuriousGeorge avatar
Thanks carl0s. I agree that Jason is doing some really nice imaging. I'm trying to get close to his Stephen's Quintet. I didn't think that was possible with an 8".

http://www.astrobin.com/268606/?nc=user
carl0s avatar
Yes, his Stephen's Quintet is really great.
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