Starlight Xpress Off Axis Guider - First light

[daz]

SX have been busy of late with a new range of camera's, the filter wheel and now the Off Axis Guider. I have badgered poor FLO and Michael at SX and I am now the happy owner of one such OAG!!

It is designed for the SX filter wheel and Lodestar but I understand adapters are available to allow use with other systems.

In the box

On opening the box, I was presented with the OAG nicely wrapped in bubble wrap, the screws needed, an allen key for the focus adjustment set screws and instructions. Everything you would expect, really.

Fitting - see photo 1

The SX Filter Wheel has a removable adapter on the scope side, this is removed. Using the screws provided, the OAG is screwed down to the filter wheel - 6 screws ensure no slippage and takes 2 minutes to do. The adapter is then re-attached to the OAG. The OAG is recessed to accept the adapter and to reduce the back focus as much as possible.

5 minutes max, and the OAG is attached to the FW and back on the scope! See picture 2

The guide camera adapter is designed for the Lodestar and it screws directly to the Lodestar barrel. No fiddly set screws here!

The pick off prism has a long knurled knob for tightening, and the adjustment was very easy to do. I found I needed to give the locking screw quite a firm turn to stop any extra "wobble" but once done, it held very firmly indeed.

Focusing

At this point, time stood still and it seemed to take forever for some sort of darkness to arrive, but eventually it did! Having refocussed the main camera - the OAG causes the focus to shift out - its then a question of focussing the guide camera. I had already set the prism prior to attaching to the scope and the H9 chip is in no way affected by the prism; there is plenty of adjustment latitude for larger chip owners.

Focusing the guide camera is a matter of releasing the two set screws on the guide head adapter and sliding the camera on its threaded adapter, up and down until good focus is achieved. This took around 4-5 minutes to do and I got the FWHM down to about 2.2. The stars looked OK to my eye, and setting up the guiding in Maxim proved the focus was OK. My guiding tests showed less then 0.5 pixels error - as it would do normally.

First Light

It still wasn't quite dark at this point, but dark enough to slew to M57 and do a 15 minute test. The result was just as I hoped - tight round stars, no trailing at all! GREAT!!

The ED80 looked a little "small" on the EQ6 now, after being sat on side-by-side bars for so long, but the whole thing just worked perfectly.

Shame the same can't be said about the actual imaging! For some reason, CCDCommander only took 4 of the 16 it was supposed to and I didn't notice until I loaded the FITS onto the main computer! And I didn't nail the focus on the main camera, so there is bloating quite evident! Still, the guiding looks good - well to my eyes at least! See the cropped image below.

So, this looks to be another excellent product from SX - just what I need to get the 12"" OO up and running. Really looking forward to going deep on some of the feint fuzzies!!!

Pic 1 - Showing the OAG in place with the recess for the adapter plate

Pic 2 - Rig back on the scope

Pic 3 - ED80 with the whole imaging rig

Pic 4 - Crop from first light image

[Ford Prefect]

Very nice review Daz, really looking forward to seeing how it works with the 12"

I might even be tempted with the standalone version for the Mak Newt

[Ant]

Wow, that looks really good Daz!

Nice and neat and lovely round stars for 15 minutes...

I too really hope they do a stand alone version.

Ant

[MartinB]

This looks like the same arrangement used with the Active Optics set up. It works well. If it is the same you can rotate the prism to pick up guidestars but I don't do this any more.

Don't stress over getting the guide cam bang on focus, it isn't critical (unlike focus for the main chip ). Sounds like the perfect solution for the big newt.

[ollypenrice]

Well crafted review, for which many thanks.

Olly

[daz]

No problem!

Will keep you posted on progress / issues, but first impressions are first rate and really looking forward to getting the canon up and running!