Webcam Focusing

[Kaptain Klevtsov]

OK, it might be a good time to summarise what the problem is with a webcam as opposed to an eyepiece.

Using an eyepiece the focus point is usually inside the chrome tube at the bottom of the eyepiece, which usually puts it inside the focusing tube. With a webcam, the sensor chip has to be placed where the focus point is to get the image sharp, which is why you need lots of inward travel on the focuser to make this work.

If there isn't naturally enough inward travel on the focuser, you can butcher modify the webcam case or adapter to allow the webcam to go into the focuser tube some more, or use the adjusting screws which hold the main primary mirror to adjust the mirror towards the secondary mirror a bit.

Kaptain Klevtsov

[AJSullivan]

Ok replacement webcam arrived and I had a clear night to try it. Alas the same problems as before. I think Kaptain Klevtsovis right. Butchering the webcam is an option, though i have already broken one, dont really want to break another. Moving the mirror is an option, but i havent got a clue where to start. Can I pay someone to do this?

[Kaptain Klevtsov]

Having just researched what this 'scope is, I've discovered that its a Dobsonian mounted Newt. Using a webcam with a Dob. is going to be very difficult as the target will move across the FOV quite quickly. However, there is an appendix in the manual which covers collimation which should be useful.

To move the mirror up the tube, I'd first take off the mirror cell to check how much movement is available. This is because the mirror will come off the ends of the collimating screws if you go too far. There are 3 small lock screws and 3 knobs on this 'scope, so you need to undo the lock screws, and unscrew all three collimating screws until the mirror is about to fall off the screws, then recollimate. Lock the locking screws down and you're done. Hopefully the mirror will have moved far enough to let you get your webcam focused.

Kaptain Klevtsov

[AJSullivan]

It is not a dobsonian. http://www.amazon.com/Orion-StarBlast-4-5-Reflector-Telescope/dp/B000AP03S4

That is my scope.

ALso moving the mirror, reckon a astro shop would do something like that? Id rather let a pro do it.

[Kaptain Klevtsov]

Ah right, sorry. My google skills must be worse than I thought.

WRT an astro shop, if you've got one close its probably a good idea. You will need to collimate yourself in the future though, so if you can get them to show you how, that'd be even better.

Kaptain Klevtsov

[AJSullivan]

Thanks mate..but what is WRT?!

Also anyone know a good astro shop in london or essex?

[Kaptain Klevtsov]

With regard to

KK