Minimum object distance for prime focus?

[dvdfilmbuff]

Is there a minimum distance for prime focus imaging?

I have set up my scope in the garden for an evening session, collimated the scope using my cheshire (Looks nicely collimated now), checked the focus on a TV aerial a few houses away, and using a 40mm plossl i get really sharp focus.

However, when I add the SPC900NC i just get a white screen. Even when focuser is moved in and out I dont get an image.

Is my test object too close?

Cheers

Mike

[pete_l]

However, when I add the SPC900NC i just get a white screen. Even when focuser is moved in and out I dont get an image.

Is my test object too close?

It's possibubble. Does the screen go dark when you put your hand over the objective?

Is there a distant streetlight you could try "hitting" while waiting for stars to come out or clouds to clear.

[dvdfilmbuff]

It's possibubble. Does the screen go dark when you put your hand over the objective?

Sure does. I have an end cap on the tube at the moment and the 900 is dark.

Is there a distant streetlight you could try "hitting" while waiting for stars to come out or clouds to clear.

no, but the moon is out! will try that!

[dvdfilmbuff]

guess its still too light? can see the moon perfect through the 40mm, but still white through the prime focus!

[dvdfilmbuff]

Ok, think i sussed it out.

1.Bl**dy laptop blue screened! gggrrr

2.Rebooted and camera has been set to Gamma 100 and Brightness 100. Reset cam to defaults and get a normal screen now.

Still not seeing the moon though! - Could be that the camera is carked! Its not been used since 2007, but I cant see how as I am getting data from it.

Will wait until it gets a bit darker me thinks.