M51 Luminance 10" LX200

[ChrisLX200]

A few days a go I tried my 10" LX200 SCT with the Atik490EX, results were promising but the conditions were poor. A better night tonight so have been collecting a few subs for M51 in LRGB. This is the rough-processed (no flats) stack of 8 x 10min luminance. Managed to get the G and the R but no B yet.

Meade 10" LX200 + f/6.3 reducer

Atik 490EX @ 2x2

Guided with Lodestar

Losmandy G11+Gemini

ChrisH

[ollypenrice]

Lots of detail there and very shapely stars. The outer halo will need really good flats. Could you go beyond 10 minutes? Your guiding seems perfect.

Olly

[alanjgreen]

M51 was great last night. I saw the spiral arms visually from my back garden for the first time ever!

Highlight of the year so far for me

[Stargazer33]

That looks like a very promising start. Can't wait to see the full LRGB image!

[ChrisLX200]

Lots of detail there and very shapely stars. The outer halo will need really good flats. Could you go beyond 10 minutes? Your guiding seems perfect.

Olly

Thanks Olly. Yes I can go out as long as needed but worried about burning the stars binning 2x2 with a max ADU of only 17K. I get horrible vignetting with the f/6.3 reducer and desperately need flats, the outer halo is already there I think but I probably clipped it to black when processing. I might be better just going with f/10 and forget the reducer, I'm only going to end up cropping the outer regions anyway!

ChrisH

[sologuitarist61]

Wow, that is very good Chris!

[Xplode]

Very nice and detailed. I think you are one of a few who gets great images with an SCT

[ChrisLX200]

Thanks Olly. Yes I can go out as long as needed but worried about burning the stars binning 2x2 with a max ADU of only 17K. I get horrible vignetting with the f/6.3 reducer and desperately need flats, the outer halo is already there I think but I probably clipped it to black when processing. I might be better just going with f/10 and forget the reducer, I'm only going to end up cropping the outer regions anyway!

ChrisH

Well I discovered I had the spacing of the reducer all wrong - almost by a factor of 3x !  The Celestron f/6.3 needs 105mm spacing between reducer and chip face, mine was nearer to 300mm so no wonder it was not working correctly for me. In my defense it couldn't go anywhere else the way it was, only between the SCT visual back and the secondary focuser. However I have found a way around it although some serious mods of the reducer were necessary.

I turned the body down in the lathe to 1.990" o.d. so it can fit inside the focuser tube, then threaded the end 42tpi so it would screw onto the end of a standard 2" nosepiece or 2" filter cell. Now the spacing is correct.

Turned the body to size and threaded the end 42tpi:

The reducer cell now screws onto the end of the IDAS LP filter, the spacing is correct at 105mm:

The whole lot slides into the 2" focuser tube:

So I hope to give this a try next time out to see if the vignetting is at least significantly reduced.

ChrisH