would at back focuser cause webcam problems

[firefox]

Would at back focuser cause webcam problems?

I uploaded this photo, asking for some advice, I spent 30 mins trying to focusing on Jupiter, after successfully imaging the moon. I was using my 11inch celestron 11inch Edge, with the back focuser attached and the camera was the DFK 21AU618.AS Colour USB Camera. I know the picture is out of focus, but my question is what could have caused this to happen, It would not focus in, the sky was clear, it was about -1, there was no dew on the glass. Any advice please

[Stargazer33]

Hi,

By back focuser, I presume you mean one of these?

I am not experienced with your camera and very much as a layman I would say that you don't have enough travel on your 'back' focuser to bring the image to focus.

Did you try to adjust the main mirrors position on your SCT? If the mirror was at the wrong end of its adjustment for your rear focuser to compensate, that may be your problem. I believe some people either set the mirror in the middle or adjust it in combination with the rear focuser. Once you have the mirror set up where the ep/camera/barlow set-up you are using can be brought to focus, you can then just use the rear focuser for fine adjustments.

I'm sure someone with far more experience/knowledge/common sense will come along soon and give you a decent answer!

[Cornelius Varley]

A focuser fitted the the visual back of the telescope (back focuser ?) wouldn't cause the problem itself. You need the set the drawtube of the focuser at about the midpoint of its travel then adjust the scope's own focuser to get a focused image and then fine tune with the fitted focuser.

[JamesF]

Agree with Peter. Remember that Maks and SCTs focus by changing the effective focal length to get the image plane to coincide with the eyepiece or camera, so if you move it back a fair way by adding a second focuser you'll almost certainly need to move the primary mirror to bring the focal point somewhere within the range of travel of the new focuser.

James

[firefox]

thanks guys

will try as soon as the weather clears up

[Stargazer33]

Good luck with the weather!

"A woman called the BBC and said that her daughter told her that a hurricane was on the way. Well don't worry, there isn't...!" Poor Mr. Fish.