ED80 and Quark

[gnomus]

I got my Quark just in time for the eclipse. On the day in question I used it on my Skywatcher ST-80 and got some wonderful views and images.

Today, I thought I'd try the Quark on my Skywatcher ED-80. Here's the thing - I couldn't get it to focus. The problem was that I did not have enough inward travel on the ED-80. I put an extension tube in after the Quark. Still couldn't achieve focus. I had to go back to the ST-80 to get an image I could focus.

Is there anything I can do about using the Quark on my ED-80?

Thanks in anticipation.

[MattJenko]

Are you using a diagonal? You could try putting it directly in without one to confirm how much more inward travel is required and then look to see if you can find a smaller diagonal?

[Moonshane]

Stu uses his quark before the diagonal. I wonder if this would make any difference? 

[Stu]

What size diagonal were you using? A 2" has a much longer optical path than 1.25". I was actually using a prism in my 85 which is even shorter than a 1.25" diagonal.

I don't recall having any issues and I think Shaun (Pig) uses a 80 Equinox with no trouble. Will try a few combinations tomorrow if the sun pops out

[gnomus]

Thanks all for the replies.  I was using my 2" diagonal and this was placed before the Quark.  If I get a chance I may try Quark before the diagonal (in which case it will be a 1.25" diagonal).  For completeness, I was just using my standard Celestron 40mm plossl as eyepiece.  

[Stu]

You could try the 1.25" before and after, given the barlow in the Quark it should be different