Star Diagonals In Imaging

[Mamsoth]

How do! I have a question that is of a noobish nature. I am just starting out in the world of imaging and have got some good images of the moon and Venus. I use my celestron refractor with the star diagonal removed (the star diagonal is filthy and i don't want to risk getting the webcam chip dusty).

My question is this, other than image orientation does using a star diagonal make any difference when imaging i.e image size and image quality

[jgs001]

The diagonal has no effect on the image directly, although I guess if it's particularly dirty that may affect the quality. A diagonal can be used to put a barlow further from the camera to increase the effective magnification of the barlow. I don't use a diagonal personally when imaging.

[brianb]

I don't use a diagonal personally when imaging.

It's always better to avoid using more glass than is necessary ... an extension tube may be required to avoid a diagonal but it's cheap and has no optical parts which might distort the image. The only good reason for using a diagonal when imaging is with a fork mounted scope when it helps the camera not hit the mount when near the zenith.

[Dave Smith]

I use a diagonal on my guide scope so the guide camera can reach focus. This is purely because I don't have a spacer and loss of some quality is not important for the guiding. I never use a diagonal (unless it cannot be helped - like the example given by Brian) for the actual imaging, it can only be detrimental to the image.

Dave

[Mamsoth]

Thanks for the helpful replies everyone