M101 from Thursday also LX10

[Magnum]

I took this last thursday with the LX10 OTA on EQ6pro and Canon 400D, total 1hr 15min, in 5 min subs. but I am struggling trying to remove the diagonal banding in the background, with my other pics I used noels actions to remove the horizontal and vertical banding but for some reason in this image its diagonal, and there is no action for that.

Lee

[peter shah]

the diagonal noise is caused by poor signal and drift in the fov...better alignment and longer exposures would sort it, also you can do bad and unreliable pixel mapping on your data, it will reduce the effect considerably but not get rid of it totally. But to be honest what you have is good....not an easy object to grab

[Magnum]

Thanks Peter, that makes sense as I am suffering with southward drift between exposures even when phd graph is nice and flat, so I am at this moment doing a drift alignment

[nebogipfel]

This is probably a crazy suggestion but what would happen if you rotated the image so that the bands are horizontal or vertical and then used the action?

[Magnum]

I will give it a try!

I spent 3 hrs drift aligning, until I could not detect any north/south drift in 15 mins, but when I setup my phd guiding again, it had not make any difference, I can still see a constant southward drift from one exposure to the next and anything over 5 min the stars start to look slightly trailed, but my graph is almost perfectly flat, this is baffling me now. How can the phd graph be almost flat with only tiny corrections but the images still show drift?

[Beardy Bob]

If the concern is star trailing after a good alignment, have you considered that it may instead be one of the guide scopes or the cameras slipping or moving in its fixings rather than poor alignment?

Or it could be bowing of the scope or fixings, which is particularly noticeable if the centre of gravity of one scope is passing over/beyond the other (or from one side of the mount to the other) during exposures.

If so, tightening everything up and trying not to let anything track beyond a 'flip point' (if that makes sense!) could fix it.

[Magnum]

Ok I will check everything and try again!

Lee

[EdF_uk]

Lovely image . Well done.

Ed