Maksutov-Cass versus Newtonian

Serious case of aperture fever alright

But in reality, the larger aperture is not necessarily to see deeper, just to enable quality photometry measurements. And of course, see fainter asteroids and faint Supernovae...

I think the Newt seems to be edging ahead.

Dave

Dave: I'm thinking aperture is the keyword alright.

OK - another issue has 'arisen'

The 16", whilst within my price range, has a 2" Crayford focuser. This will carry (and move) about 4lbs of kit. Unfortunately, I will be using about 12lbs of kit.

I could get a Van Slyke focuser that will hold as much as I like. The focuser would add on another couple of pounds.

But my worry now is that such a mass on the end of a Newtonian tube would introduce unwanted flexure. The manufacturer said they can beef up the section of tube at the focuser by installing a steel band around it. Somehow, I don't get a warm fuzzy feeling...

Any thoughts or ideas?

Dave

Hi Dave,

I'm afraid I'm Johnny-come-lately to this discussion as I've been away for a while and am just catching up, however...

Your primary interest is in photometry and not visual work at the eyepiece. If you go for a Newt then you have the option of doing away with both the secondary mirror and the heavy duty focuser on the side of the tube. Depending on the size of your CCD camera, you might even end up with a smaller central obstruction if you mount the camera at prime focus, a little bit further up the tube than the secondary mirror. You still need a spider and a focus mechanism, but you are eliminating one reflection (4%-6% light loss per reflection) and you loose the problems associated with collimating the secondary mirror and the vignetting it may cause, and the focuser can be relatively light weight. Ok, you still have to collimate the camera/focuser, but once it's done you won't have to touch it again. You will still be able to mount one or more Barlow lenses and/or filters in front of the camera by screwing them directly into the camera baffel tube.

Just a thought,

Phil.

Interesting thought Phil and it crossed my mind. Van Slyke make a beast similar to this (though its a motor primarily designed to move a secondary mirror).

How do-able is this? And it the parabolic primary the best method? Would 16" work or should I go to 18 or even 20"? I guess it depends on the imager dimensions (though the filter wheel is even bigger...).

Thoughts?

Thanks
Dave

Of course, I'd prefer not too, but an 16" RC is really out of my price league...

Dave,
Sounds like a few extra €€s might help the decision here. Check out planetary.org
They're offering big bucks for amateurs helping out on potential asteroid impacts. With your record I would reckon you would qualify no problem for up to $10,000 of a grant.