skywatcher 102t focus

[Cinnamon87]

Hi all

Looking for a bit of direction. I have the much under appreciated 102t Skywatcher. I have the asi1662mc which is my new dedicated astro-camera but i'm having a few issues with focus and confused about what I need next, focal reducer or extender.

Everything is set-up and I have an image BUT, it is slightly out of focus. essentially, I need to reduce the distance from the camera to the front of the telescope. the focus is in as far as it can go! what do I need?

Any direction would be greatly appreciated.

MTIA

[michael8554]

If you have the diagonal in place, how are you attaching the camera, sounds like it's too far out of the diagonal ?

If you don't have the diagonal, you won't get focus with the camera screwed to the threads on the focuser, it will need an extension about the same optical length as the diagonal.

The Focal Length is 500mm, so the camera sensor needs to be about 500mm from the OTA front elements.

Roughly measure 500m back with a tape measure, to give you an idea of what length extension is needed.

Michael

[Cinnamon87]

Hi Michael

Many thanks for your response. I'm just about beat for the night so will hope for clear skies tomorrow so I can check again. I think I actually have an old extension tube in the shed. I've attached what I did tonight which did work, after a fashion but the moon was so big with the x2 barlow 🤣, but I actually managed to focus.