|
My imaging setup (primarily at the moment) is imaging with the 80ED with the Canon 350D and guiding in the 10" LX200 at 2500mm focal length with the ImagingSource DBK31. The disparity between the two focal lengths is not a problem - it is just less tolerant of issues when guiding at the longer focal length. Clearly, if I can guide well at 2500mm, there is nothing at all noticeable wrong with the image in the 80ED. I've even had the guiding stop working for 10-20 seconds during an exposure, and even though the image has moved a bit in the guide cam, can't see anything wrong in the main image because of the difference in scale.
Firstly, make sure you're well balanced, as well polar aligned as you can be. Then play with the values for the guide movement amount. If your mount has PEC, you might want to try using it if you've eliminated the other issues. You need different settings for different focal lengths. The help suggests changing the value based on the focal length your guiding with - I just went with trial and error - if I did a "force calibration" and the settings were too much that the star image went off the screen, then I knocked it back a bit until I could get it to work.
When I have the rig setup the other way around (imaging at 2500 and guiding at 600) you've got to play with it a bit otherwise the star just wanders off. Generally I've had less success this way, but I just haven't tried as much so it could be just a matter of practice (using the 80ED gets most of the objects I'm interested in at the moment) - at 2500mm, there's not as much pretty stuff to take photos of without lots of work!
I have to say I make the guide box 50 pixels wide, to give it the best chance of not losing track, but then again, my guide cam is 1024x768 pixels, so there's a bit more room to move.
The biggest problems I had were when I was unbalanced. I had a 3D balance system put on (it's fork mount on a wedge), and the immediate improvement to my guiding was massive. It went from haphazzard and mostly unable to last through a 5 minute exposure, to quite capable of going 30-40 minutes without having to readjust PHD.
How do you have the 2 scopes mounted? Side by side plate or piggy backed somehow? Balance could well be an issue, but differential flexture between the two scopes if they are not well secured could explain the movement too.
Turbo
|