Focusing ED80 - Saturn

[Viv]

Hi all,

Was my frist night out, last night with the ED80.

I just love the scope, so nice.

However for images, focusing seems to be challenging. I can't get any sort of focus / view without the diagional.

This one below (my best Saturn to date), is with the flashed SPC 900 (one minute of video, through registax 5), but using the diagional (was outside until 2am & so very tired now - but happy).

Question please - for those with ED80 - what do you connect without the diagional ???

(I tried every conceviable option - barlows / extension tubes / etc / etc)

Thank you for any help, was getting quite fustrated early last night.

[Zakalwe]

If you do not use the diagonal, then you will need a 50mm extension tube to achieve focus. The extension tube is needed to replace the length in the light-path that the diagonal occupies.

It's very easy to pass right through focus when using a webcam. Once you do get it focused, mark the draw tube with a pencil mark so you can get it near the next time.

[JamesF]

Getting decent webcam images of Saturn isn't easy and can be frustrating at the moment. I reckon I had a window of about three hours last night when the planet was high enough and the seeing good enough to be worth the effort, and that time disappears very quickly. Getting the scope well-focused is not straightforward and more frames would probably help if you can manage it. I shouldn't worry about not being able to achieve focus without the diagonal. Just leave it in for the moment.

I made up a focus mask to try to improve my focusing, but that does mean putting the mask on the end of the scope, slewing to a star and getting everything as good as possible, then moving back to Saturn and taking the mask off without changing anything in the visual train. At high-ish magnification I found an RDF wasn't good enough for locating the planet and have gone back to a visual finder. Alignment does need to be spot on though, so it's worth spending some time during the day sorting that. If you don't have an eyepiece with a reticule to help then sharpcap and wxAstroCapture both display one over a webcam image.

James

[Viv]

Thank you both for the replies.

Zakalwe - tube ordered, & good idea with the pencil line