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Newtonians have really made a comeback in the last few years as superb imaging machines since the advent of the Wynne corrector like that used in ASA scopes.
Some of the finest widefield images have been with ASA Newtonian scopes (when they worked) as per example Wolfgang Promper.
SCTs strength I understand is planetary imaging. Apart from Fred's great images I generally do not see too many high quality SCT images. That's for a few reasons.
Long focal length imaging is hardest of all as all the imperfections of balance, tracking, polar alignment etc etc gets magnified along with the image.
SCT alt az mounts have long been known to generally speaking (I am sure there are some good ones around) been great for visual but simply inadequate for long focal length imaging. That is if you want to do image exposures longer than a minute. So unless you get yourself a very expensive mount with an SCT or Meade ACF (they seem the best) OTA only you probably will be disappointed/frustrated.
So you need to work out what type of imaging you want to pursue. Short focal length wide field imaging will be easiest. It will be most forgiving and most likely to end with a good result even with some imperfections of balance, tracking and guiding.
Then there is the question of F ratio. SCTs are usually F10. That is not a good imaging F ratio. Whilst CCD cameras are linear in response meaning F5 and F10 will give the same signal to noise ratio, to get shorter exposures 2 scopes of the same F ratio means the one with the larger aperture will give the shorter exposure times for the same brightness of image.
So ideally for an imaging machine (given setup time or travel,cloud, work, moon limit our available imaging time) then a widerfield, fast (F5 or less) Newtonian of largest affordable aperture will outperform other machines easily.
I have seen lots of fast (often less than F5), large (bigger than 8 inches) Newtonian images over the last few years that are simply sensational. Newts give very sharp images due mainly to the fact that a simple Newt mirror is easy to make very perfectly compared to other odd shapes.
So I suggest if you want to go the imaging route you:
1. Buy the best mount you can afford. A good mount with a crap scope will be better than a good scope on a crap mount.
2. Go Newtonian and go shorter focal length with low F ratio and get a nice corrector like a Wynne 3 inch corrector from Phillip Keller or even a Televue parracor.
3. Setup to do autoguiding well. The QHY is a popular choice with free PHD guiding software.
4. There are also upgrades available for the EQ6 including a gear/worm coating that reduces periodic error tremendously. if you can afford it you would be better of with a smaller Tak mount rather than a G11. I have had Gemini system and it is a pain and time consuming and not particularly user friendly. Tak leaves it for dead. Any Tak model. A lighter one would be an EM200 and they can be gotten 2nd hand on Astromart for around US$3300 or so perhaps less. It would last you a long time and you will get results instead of the inevitable constant upgrades which is where the real money is often spent in this game trying to make something work better than it does out of the box.
A nice Newt on a 2nd handTak EM200 with a AT66ED or similar guidescope and a QHY guider would probably cost the same as a largish SCT with Alt Az
that is fabulous for visual but a pain for imaging.
The difference in results speaks for itself. I can guide you to numerous examples of superb images with similar setups to the above.
My 2C.
Greg.
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