Skywatcher 130PM SynScan AltAZ - A no-go for astrophotography?

[Nemesis6]

I've seen some reports of this scope not being good for astrophotography; lack of focus is the thing that keeps being brought up. I've read that a barlow lens might solve this, but that of course limits the view... So what's the deal here?

[Cornelius Varley]

The lack of inwards focus is the main problem with the telescope when using a DSLR. The sensor cannot be placed close enough to the point of focus. By adding a barlow lens to the optical path the point of focus is moved further away so allowing the sensor to be placed on the point of focus. Another problem is the mount itself. The mount tracks in an up/down, left/right fashion, rather than in an arc that follows the path of the stars across the sky, as produced by equatorial mounts. This means that long exposures, more than 15 seconds or so, will show up the zig zag motion of the mount. Webcam photography of the moon and planets should be ok for the telescope/mount as you will need a barlow to increase the image scale and the processing software will be able to realign the individual frames of the AVI.

Peter

[ollypenrice]

For webcamming a Barlow is fine but for deep sky the last thing you want to do is to slow down the focal ratio. It mightily increases exposure time and creates huge demands on your tracking (which would be a no go anyway in Alt Az.) The generally accepted minimum mount for DS astrophotography is the HEQ5.

Olly

[jgs001]

The focus issue is far more of a problem than the mount for imaging. Whilst the mount is a long way from ideal, it can still produce good results, and if it's what you've got then go for it....

I've used my NexStar SLT to image for 2 minute subs on M31 and it worked out well. I can post a couple of examples if you want me to (it might take me a little while to find them... )

What camera and lenses do you have, as you don't need a telescope to get decent DSO images ?

[Nemesis6]

The thing is, I haven't got a camera or a lens yet. If this scope really is more trouble than it's worth, then I'd rather go for a new, equatorial scope first before going for the Canon EOS 1000D I had planned to buy.