diy web cam no secondary mirror

[ponytale]

has anyone out there put a webcam on a newt where the secondary should be ? prime focus ? perhaps in a sliding tube or helical focuser on the spider for fine focus adjustment , and adjustable spider arms for collimation.

as the webcams today are so small and light especially out of their casings, the spc900 for example . also would the image contrast be better ? than off the secondary? plus less moving parts to cause wobble/ vibration ?

any thoughts or feedback welcome

[Telrad]

Hi ponytale, unfortunately I haven't tried that. I've only used the conventional method.

I would be interested to see if anyone has?

[GazOC]

TBH I can't see it making much difference. The loss off the light from the secondary would be negligible especially when you are only stacking the best shots from a webcam.

[Parus major]

would the ccd not have to be quite far out the front of the tube? Also, wouldn't collimating the primary case the focus to shift?

[FraserClarke]

I think the main advantage comes for very fast systems (f<4) where the size of the secondary would be a larger obstruction than placing the camera at prime focus. You also need to worry how to get the signal out (the wires are probably wider than your spider vanes), and potentially any heat coming off the camera (i.e. if you have a Peltier cooler).

It's very possible (a lot of professional telescopes have widefield cameras at prime focus) -- but it's probably not worth it unless you're buidling a specialise system.

[haitch]

I think the main advantage comes for very fast systems (f<4) where the size of the secondary would be a larger obstruction than placing the camera at prime focus. You also need to worry how to get the signal out (the wires are probably wider than your spider vanes), and potentially any heat coming off the camera (i.e. if you have a Peltier cooler).

It's very possible (a lot of professional telescopes have widefield cameras at prime focus) -- but it's probably not worth it unless you're buidling a specialise system.

If there were 4 wires to the camera (I think there actually could be a max of 5 for USB) then you could use the vanes themselves as the conductors.