Future refractor plan

[vphotographic]

Hi all,

My current kit is a SW 127 and SW eq5 goto mount.

I was thinking of in the future getting a refractor to compliment the 127, I like to play around with imaging but nothing major.

Would I see/image much more with a refractor ?

Paul

[JamesF]

A refractor of comparable size that could be used for DSO imaging would be quite expensive. You'd probably not see much more with it, but the extra light you'd collect as a result of not having a central obstruction may give you a noticeable increase in contrast.

However, many people using refractors for DSO imaging use quite a small aperture scope, often 80mm or smaller. For imaging that's not really an issue because cameras don't work the same way your eye does, but for visual use it might mean you struggle to find or get a good view of some things you can see with the 127. You'd really need something relatively small for the EQ5 to be able to cope for imaging anyhow. The better-corrected refractors still aren't cheap by comparison to reflectors.

I think refractors such as the ST102 and ST120 are great for getting outside quickly and whizzing about the sky with, but they do suffer from noticeable colour aberration and aren't really best-suited for imaging.

James

[ollypenrice]

The key difference would, or could, be focal ratio. For imaging I'd consider F8 as being the slowest tolerable F ratio. Faster would be better, espcecially with a DSLR. However, here's the rub; fast refractors are expensive to make because imaging needs excellent colour correction. The ST series are pretty unsuitable with big blue haloes around stars.

There would be little to choose, visually, between your Mak and a similar sized apo. You'd get a wider field from the shorter FL and not much else. I love refractors but not because they represent good value for money. They don't!

Olly

[vphotographic]

Thanks guys I think I'll stick with my Mak for a couple years now.

My other option is to use my 70-200mm f2.8 dslr lens on the mount but can't see how it attatch, it has a collar on it.

Paul

[johnrt]

DSLR on an ED80 would set you on your way to some decent images.

[vphotographic]

I'm thinking direct to the mount without ota for wide field stuff

Paul

[JamesF]

If you want to use a DSLR and that lens then probably the easiest way to start is to mount tne entire camera on the EQ5 by making up a dovetail with either a tripod mount or just the tripod screw that would normally be used to mount the camera on a tripod and work your way up from there. To get longer subs you'll need to think about guiding, but there's no reason you couldn't start unguided and I imagine you'd get some acceptable images to begin with.

James

[JamesF]

DSLR on an ED80 would set you on your way to some decent images.

The ED80 would struggle for visual use compared to the Mak if you want to use it for both, though. If you already have the DSLR and lens I'd give that a whirl first.

James

[johnrt]

I thought he was keeping the Mak?

The ED80 would struggle for visual use compared to the Mak if you want to use it for both, though. If you already have the DSLR and lens I'd give that a whirl first.

James

[vphotographic]

I could utilise the small white dovetail thing that came with the eq5 head I guess.