Image moving from frame to frame

[gustavo_sanchez]

Hello,

Maybe this is a dumb question. I have noticed that when I am taking pictures, there is a movement in the image from one image to the next, as when you dither (which I am not doing). The movement is only in one axis, like when it is trailing, but the stars are still round! I mean, in one image a star is in one place. In the next image, the same star is a bit to the right. Next image, same star moved to the right even further. It is completely round in each image, without dithering. Would expect this is the cause of the dark borders created after stacking...

Why is this? Is this the guiding?

Sent from my Nokia Lumia 1520 using Tapatalk

[jambouk]

I've noticed the same, and i don't guide. I've always put it down to my poor polar alignment; not so poor that i still get round stars after a 60 second exposure, but poor enough that the bulk of the average location of the image over those 60 seconds appear to move in the next 60 seconds; so i think it is poor tracking. I can't see it is camera shift as it is always moving slowly in one direction and not flipping back the original way.

But i'll be interested to know what the experts say.

James

[swag72]

This is generally polar alignment if you are not dithering and yes it will cause the dark borders around the edges. As long as your stars are round, I'd not bother with it. Cropping off a little around the edges to tidy things up isn't a deal breaker.

[Davey-T]

Probably PA, try doing a long sub to see if it trails.

Dave

[Freddie]

If the frame edges don't line up as you say, then it's PA as in this recent thread

http://stargazerslounge.com/topic/198770-image-drift-across-capture-screen/

[Jannis]

I've noticed similar thing. And what's more odd, is that the mount is obviously awere of it.

With no guiding, if i for example select M31, and let it track it, and i come back in a while, it's clearly moved significantly, and when i puch ID on the handcontroller, it sais it's quite off target. Regardless if i track with or without PEC, do deep sky, lunar or planetary...

I first thought it was moving off target because my finder-guider was flexing, so i tapped the finder-bracket and put in 6 screws to hold the scope intead of the rubber o-ring, 2 screws, and the spring - but no difference. Then i accidently noticed it was tracking incorrectly even without guiding.

No idea why, or how to fix it.