[Leo.G (Leo)]

I have an old Tasco 17TR 80mm x 900mm refractor I purchased new in 91 which has been highly modified. It has a Vixen ED lens cell (it screwed straight on after having a thread machined on the pipe), baffles, flocking and a machined alloy adapter to fit a WO Synta DDG focuser.
To obtain visual focus after fitting the adapter and focuser I had to cut the tube 50mm shorter and I used it mainly for visual.
The other night I ran out with it thinking I'd chuck it on a small Celestron mount which belongs to a 70mm reftactor I keep meaning to give to a friends kids, slapped my Niokon camera on the back and wanted to snap the moon, just rough quick shots playing. I couldn't obtain focus, I just couldn't get the sensor close enough to the focal point. The best I could get was a white blob and though some cloud had drifted over I can usually make out the silhouette of the moons darker features

I've read a lot which tends to recommend the easiest option is to add a Barlow. I didn't want to do that.
Is my only other option to further trim the tube down shorter?


It's not a major issue to cut the tube but I'd rather not remove too much, I guess I could always TIG it back on if necessary but that would be a real pain to be honest.
I also don't want to take 5mm off at a time and trial it to see if I can achieve focus because that becomes overly time consuming.
I guess 20mm off and I have extenders which the Williams Optics focuser can handle. It's obviously not a primary imaging scope but I like to play on occasion.