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Old 08-05-2021, 09:02 AM
Emuhead (Andrew)
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Emuhead is offline
Join Date: Oct 2019
Location: Melbourne, Australia
Posts: 194
Originally Posted by kosborn View Post
I'm very late to the conversation but thought I'd add my recent experience.

I started with an Esprit 100ED about 3 years ago and wanted to add more focal length. I thought carefully about adding an 8" RC but in the end decided to go for a high end Newtonian. I was nervous about the size and weight of the Newt (and it really does look top heavy in the attached pic) but it actually works well on the EQ6-R as long as there isn't too much breeze. I was equally nervous about the collimation and the big f number of an RC. A Newtonian is infinitely easier to collimate than a Ritchey-Chretien!

I dither every sub and lose a lot of time waiting for the scope to settle, but I live in a Bortle 4-5 suburb of Canberra and don't have to throw away too many subs. The Newt is a 254mm f/5 carbon fibre tube from Sidereal Trading and I've added OAG to reduce weight as much as possible. It weighs in at 17kg with imaging train which is a lot for an EQ6-R but it all seems to work. With a Baader MPC Mk III coma corrector it gives me a great flat field edge to edge and the focal length of 1270mm together with an ASI1600mm and ASI2600MC (and with the Esprit with or without a Starizona 0.65 reducer) gives me a great range of focal length and framing options.

The bottom line is don't underestimate what you can get with a good quality Newtonian!

I bought the 8" Quattro f4 800mm and haven't taken it off. Absolutely love the thing and its speed, and i have a 550mm refractor that I've not yet used because i like the longer focal length, and I cant fault the newt. Grown to really like diffraction spikes too.

So a 10" mirror on an eq6r (f4 or f5) is not too heavy after all, I'm hearing more & more from people who have done it successfully. Just might consider that.. 1000mm f4 or 1200mm f5 is the question, guess this thread has shown it makes no difference to detail/resolution as long as the pixel scale still falls in the sweet spot, it'll be the exact same image if cropped to match, so may go the f4 route for the speed & to keep the windsail size down.

Last edited by Emuhead; 08-05-2021 at 09:17 AM.
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