[Joshua Bunn (Joshua)]

Hi All,

Over the last 4 or so months ive been trying to chase down the source of my star elongation in my images. (my thread on refraction at the horizon was about trying to find the issue)

The gear is a cdk 12.5, PME, stl11000 with bolt up adapters.

ive tried every test i can think of to try and track down the source of any movement in the scope and so far i havent found the source. Ive tried many things and Steve Mohr has been assisting me over the phone and email but im still unable to eliminate this elongation.

What hapens is i would point to the zenith and take a picture and collimate there and all stars on the chip would be round. then i would slew to say 40 deg altitude in the south and take an exposure of 30 or 60 sec (same as zenith) and the star elongation would be to the top left of the chip - over the whole chip.

then i would slew to the north and take an image there at 40 deg altitude and the elongation would switch to the top right of the image and still over the whole chip (not just in one corner).

I dont think its guiding error as my guide graphs are indicating sub pixel guiding. the elongation is more than this. Im not using a guide scope, but the internal guide chip on the stl11000.

One other thing is the elongation of the stars (wherever i point in the sky) is parallel with a line from the horizon to the zenith.

So, i want to iliminate the camera from the picture. I would like to try another camera on the scope to see if the problem still exists or goes away. I have a 5d mkii but i cant be sure it wont move as its only using thumb screws to hold things in place.

Would anyone with an stl11000 lend me their camera to try this out? i could possibly use a stl 6303 but the mounting face plate needs to be the same as an stl11000 so my adapters fit.

Of course i would pay for insured postage etc to and from WA.

If someone would be kind enough to do this, please post here, PM me or phone me on 0428650851.

I'm all ears for sources of the elongation as well

thanks
Josh