2.7 vs. 4 inch focuser TOA-130?

Don't want to appear dumb, but what are the advantages/ disadvantages to the 2.7 vs 4 inch focuser? What does the "inch" refer to: Backfocus? Would I prefer the extra cost with the 4 inch for a) binoviewing? b) CCD imaging?

Thoughts appreciated. Looks like a great scope....

Marc W

The size refers to the diameter of the focuser/drawtube. The 4" focuser includes (unless I'm mistaken) a Camera Angle Adapter; the 2.7" does not (but one can be purchased for it). The 4" focuser is more heavy-duty for purposes of holding heavier accessories (especially big CCD's), and I believe it is also meant for the bigger reducers/flatteners, also for imaging.

The TOA's 4-inch focuser is similar if not identical to the FSQ-106, and yep, that focuser is heavy duty all right! Though the 2.7" is no slouch in my experience: I had an FS-102 and hung an SBIG STL-6303 off that with no obvious issues.

HTH,
Eric

Advantages, ability to image with large chips, and I believe beefyness which could reduce any chance of flexure with any imaging. But the 2.7 can handle chips of pretty good size.

Disadvantages? Weight and it costs a bit more.

I got the 2.7 and wish I got the 4". It's not a real big deal to change later on if you want.

Regards,
Kevin