Explore Scientific ED80 focus

[Gundary5 (Shane)]

Hi all,
The above mentioned scope arrived yesterday and a beautiful thing it is. I have just the bare bones OTA as I’m going to build an imaging rig around it. However, when I try to use it visually I can’t achieve focus. Even with the 2 included extension tubes fitted it doesn’t wind out far enough. If I pull the eyepieces several centimetres out of the draw tube I get a focused image.
I don’t have a star diagonal fitted as yet, but will that really make all the difference? And with my DSLR fitted am I going to need even more extension tubes to achieve focus?

[Nikolas (Nik)]

star diagonal will make a difference definitely, try it with a barlow if you have one.Even without a star diagonal the barlow should help achieve focus.

[Gundary5 (Shane)]

I tried the Barlow, and that’s when it still needed to come out of the draw tube

[casstony]

The light path through a diagonal varies between about 60mm to 110mm.
A 1.25" prism will have the shortest light path while a 2" mirror will have the longest light path. ie. adding a diagonal allows you to wind the focuser in a few inches.