I think I have won!

[avandonk]

While waiting for the cloud to clear I decided to tilt the RH200 so it pointed at the deck. I then loosened both Zero Tilt Adapters sequentially and made sure everything was fully home before retightening the bolts. This would eliminate any small misalignment in the image train due to assembling in the horizontal position.

After the cloud finally went away I took a series of exposures in HA. Each exposure differed by 200 steps of the Atlas focuser or about 20 micron of travel..

Here is the single 4 minute exposure where focus was best. No flat or dark correction.
Full resolution 10MB

http://d1355990.i49.quadrahosting.co..._-007_240s.jpg

Managed to get some quick data. This is 10x4 min with 3nm NII of the SMC processed upsized at x1.6 in size. 5MB

http://d1355990.i49.quadrahosting.co.../SMC_NII_L.jpg

Note this was collected with a near full Moon and the SMC fairly low in a light polluted sky.

It is obvious something was not fully inserted home. I may not need to touch the back plate adjustment at all.

The guiding still needs a bit of tweaking.

Bert

Tomorrow the weather report is favourable. We live in hope.

[dvj (John)]

Wow, huge improvement. Suddenly, all the stars are looking much tighter. I don't think I've seen the SMC in NII. I can imagine 4 or 5 hours on this, rendering a super smooth, noise free image.

j

[dvj (John)]

Something I forgot to ask. Is there a critical mechanical distance between the corrector element and the focus point with the RH200?

[strongmanmike (Michael)]

[avandonk]

Originally Posted by dvj

Something I forgot to ask. Is there a critical mechanical distance between the corrector element and the focus point with the RH200?

Focus is 115mm behind the rear plate and is fixed as the corrector is fixed.

Only the primary mirror needs to be aligned for collimation.

Bert

[bmitchell82 (Brendan)]

That seems to have done the trick bert! don't you just love it when the fix is just so so simple.

Hopefully the fix for the weather in melbourne is the same! hahaha

[marco (Marco Lorenzi)]

Nice Bert, it seems now stars are quite tight, in particularly in the first single image. I see some triangular stars on the stack, not sure if it is a problem of tracking or registering the images, however the speed of this scope is impressive, I believe you will have lots of fun with..

Cheers
Marco

[gregbradley]

Great job Bert. I have found adapters not fully seated as a very common cause of out of whack stars on my setups.

That's impressive because your camera's sensor is larger than the spec for the scope.

I think those few odd stars long the top middle are brief larger guide errors or they are unresolved double stars. Probably a blip on your guiding where the guide errors went to 2 or 3 for a few secs.

Greg.