First light with Sac10

Hi all,

Been dying to try this out since it arrived from the US. We had a clearish night on Saturday here (great seeing, but very hazy high cloud) and M13 was obvious, so I decided to target it.

At 24 seconds the tracking was still poor so I shot @ f6.8 & cropped the image. Pity that the trails are still so noticeable.

flickr.com/photo_zoom.gne?id=191616110&size=l

Televue Ranger 70/480mm @ f6.8
Gain 37 (out of 64)
30 * 24sec shots averaged.
CG5GT
Seeing 4/5
Transparency 2/5

I'm very impressed the imager. Nebulosity really is a dream to use & each individual frame had way more detail than my 7D couple to the SCT. With improved tracking it should be possible to get some lovely images. I must try to drift align tonight to see.

Trev

Nice effort Trevor. Like anything else, it'll take a bit of time to get used to it and get the most out of the camera and your astrophotography setup. Looks promising so far.

Clear skies,

At 24 seconds the tracking was still poor so I shot @ f6.8 & cropped the image

Trevor - how do you change the f-ratio?

Colour registration in the image seems off (top left) though presumably that's a combination of chromatic aberration and possibly coma?

Tracking is off but drift aligning will help you - is this a mobile setup?

The background seems quite dark on my (calibrated) monitor - but M13 looks good.

The SAC10 seems a pretty powerful imager though the pixel sizes are very small. Still, leafing through the SAC10 gallery, the images it produces are very very good.

It looks like when you get to grips with the intricacies of the SAC10 we'll be seeing some super images. The best of luck!

Cheers

Dave

Hi Dave & Micheal,

"Trevor - how do you change the f-ratio?"

F6.8 is the natural f-ratio for the Ranger (70/480mm). I've started out using that as the imager instead of the sct because of the small pixel size, giving 1.47 arcsec/pixel (the SCT would give a .56 even with the reducer in place @ f6.3). Mind you, it does support binning so I may try that out on the larger scope - particularly if seeing is as good as it was last night.

Tracking is off but drift aligning will help you - is this a mobile setup?

It's a mobile enough setup, 8" Meade SCT with a rail mounted refractor on the ASGT, but I usually just observer from the city. Found an excellent program at wcs.ruthner.at/index-en.htm that should make drift alignment much easier. If that doesn't work out I'll try guidedog with the NexImage and gpusb. The great thing about the setup is being able to visually observer on the SCT while the refractor is imaging (as long as I don't touch the scope!).

Colour registration in the image seems off (top left) though presumably that's a combination of chromatic aberration and possibly coma?

Your right about the colour being off; an artifact f from all the levels processing I think plus ca from the Ranger. I'll mess around with this again. You should have seen the results when I forgot to put the IR filter on, huge bulbous stars

I was very hesitant in purchasing the camera but got a fantastic deal on it ($700 on Astromart) and now I finally see why people rave about dedicated ccds.

The SAC gallery sure is amazing eh?

Can't wait to get more practice on this and incredibly enough we have the weather for it!

Cheers,

Trev

With the SCT you're probably gonna have to bin given that we don't have Hawain skies here But the SAC10 seems a great partner for the Ranger and you can still get some fine unbinned deep sky objects with the SCT if, as last night, the seeing is very good.

WCS seems interesting - handy if you're mobile alright. If you get your alignment nailed, I'd expect great images with the Ranger. The SCT will be less forgiving of a less than perfect alignment.

I found working a colour a real pain and very time-consuming. And its a really subjective thing too - more subjecting than just greyscale anyhow.

As a suggestion, and I'm not familiar with the nebulosity software, perhaps just image greyscale until you get a real good feel for the imager and imaging. Colour adds another layer of compexity to deal with on top of the rest. But when you get 'the rest' sorted, you can really concentrate on the colour processing. Just a thought

Looking forward to seeing more images though!

Cheers

Dave

Thanks a million for the advice Dave. Grayscale vs colour was one of the things I was weighing up that night. I must try that.

Would you suggest capturing mono raws or simply discarding the colour information during processing? At the moment I'm doing the latter so I can go back to them later on and process in colour if need be.

Thanks,

Trev