Celestron EdgeHD 800 & Reducer - Help please!

[PhotoGav]

Do you own a Celestron EdgeHD 800 and the dedicated 0.7x Celestron reducer? If so, do you have a flat frame taken with that set up that you could send to me please? I am finding all sorts of problems with my reducer on my edgeHD 800 - the stars are badly elongated down the left hand side of the image and especially in the top left hand corner. Also, the centre of the flat is off set to the right. I would like to see what your flat looks like so that I can establish whether I have a duff reducer...

Thank you.

[Daran]

This is one of my master flats. The camera used is slightly below APS-C size. Top left intensity is quite low and quite some dust everywhere. Does that help?

[sharkmelley]

Sounds to me that the scope likely needs collimation.  The reducer will make collimation issues more obvious.

Mark

[PhotoGav]

Thank you Daran & Mark. I will look at the flat carefully when home, but it definitely looks 'better' than mine. As for collimation, the scope has recently been collimated and flats without the reducer are 'perfect'. FLO have been superb about this and are arranging a replacement reducer, which will be very interesting to compare... The story continues!

[Daran]

This flat isn't as smooth as it looks unstretched. Top left corner is up to 35% darker than the center. Without a reducer the illuminated field is much bigger and this doesn't happen for my camera size. Flats were taken with a QHY9 with 29.4mm*13.9mm.

[PhotoGav]

Daran, I have now had a chance to inspect your flat on the laptop and it is most revealing - thank you for posting. The important feature for me is that the light cone centre is in the centre of the image. When I use the reducer on my system, the light cone is off to the side by about 20% and the left edge has very elongated stars. Not sure what is going on with my set-up... Hopefully I will find the solution (and it won't be too expensive!) before too long.

[knobby]

Could you try a flat with the camera turned 180° to see what happens , or turn the reducer 180° ?

[PhotoGav]

@knobby - so, with the help of @steppenwolf, I have run some tests with the camera in the 12 o'clock and 9 o'clock positions. I have also taken some frames using a completely new reducer, thank you FLO! The results show that the camera is fine and the new reducer gave the same results as the old reducer. So, it seems as though the fault lies in the ota and is simply amplified by the reducer. I now need to have the ota looked at professionally... Results to follow. In the meantime I am using the scope without reducer and am pretty happy with the results that I am getting... http://stargazerslounge.com/topic/240363-m51-the-snail-galaxy-lrgb/

Hopefully I will find the ultimate solution to this issue soon...

[HenryNZ]

I know this is an old thread but is there any update on this matter. Also did you re-collimate with the reducer on?

[PhotoGav]

I tried another reducer from a newer production batch and the problem disappeared, so in the end it was all down to a faulty reducer... I hope you get yours sorted quickly and efficiently!