1st try imaging with modded 840k and no joy

[acharris77]

Hi all, I thought tonight I would try out my new toy the toucam 840k with the SC1 mod done by Andy Ellis. So I fire up K3ccd tools and goto the long exposure, and for 45 minutes I tried to get the image focused and centered, but I didnt seem to be getting anywhere.

I started by pointing the scope at the Trapezium in Orion with my 25mm EP and centered it, then I changed to the webcam and I then tried to focus it on the screen, couldnt seem to see anything on screen, so I tried 5 sec and hit the preview button, then I seen my image pop up out of focus and it tried for another 5 secs and it moved out of screen.

So I focused again and hit the 5 sec preview and closer, but still out and nearly out of view, tried this for 40 mins and getting the same, tried gain up and still seen nothing, though I did manage to get a live view up once on screen of some stars in the region, but that was it.

On hitting the preview button to preview the record, I was getting some images on screen so camera was working, but I could not see nothing on screen to focus, though that is me just not getting it right.

Pretty frustrated, so I decided to call it a night and walk away. Can anyone give some advice to help with the on-screen focusing and seeing it on screen, as I can do it with planets and moon no problem, but I could seem to do it with stars or DSO's. Feeling dejected and wondering if it is worth trying to image stars or DSO again next clear night. Thanks.

[Cornelius Varley]

The first thing to do is make your camera parfocal with your eyepiece. For that you will need a parfocal ring. I also recommend that you use an eyepiece of about 10mm focal length as of FOV of the camera is smaller than that of your 25mm and will make it easire to frame. To make the eyepiece and camera parfocal firstly aim your telescope at a chimney or building in the distance. Using the camera focus on the target then swop the camera for the eyepiece with the parfocal ring attached. Without moving the focuser move the eyepiece up and down to achieve focus then tighten up the screw on the parfocal ring. The camera and eyepiece are now parfocal and will be in focus at the same point.

Secondly, your mount is an alt-az so make sure that your are short, say 20sec, to reduce field rotation. I suspect that the reason the star had moved from the FOV is because the mount was not in tracking mode or because the 25mm eyepiece gives a greater FOV than the camera, a webcam gives a FOV similar to a 6mm eyepiece.

Peter

[acharris77]

Thanks for the advice on that, I will try using the 10mm eyepiece for the fov. I was trying 5 secs last night. Also where do you get a parafocal ring from, as I was looking on FLO and I could not see one. Thanks again.

[Cornelius Varley]

Try ModernAstronomy for the parfocal rings.

Peter