Posts Made By: Rod Kaufman

A reflectometer is a device which is capable of measuring the reflectance of aluminized surfaces. The staff at CAL Tech uses one to determine the reflectivity of the aluminum surface of the 200 hale mirror after a cleaning. I've been trying to find a source for a relatively inexpensve reflectometer but the only source I've found is a scientific paper on how to make one:
http://www.iop.org/EJ/abstract/0957-0233/8/11/008
Anybody have any information on a reflectometer?

matthew gray said:

Disaster has struck, and I need a replacement mirror for my 6 year old XT10. Orion will not sell me a replacement. Can anyone tell me where i might get a new mirror???

Thanks for any help offered....

matt gray

This place has been around for quite awhile:
http://www.e-scopes.cc/
You may wish to contact them for further information as they appear to offer various mirrors, but since you didn't specify what focal ratio you need, it's a bit hard to tell.

Lawrence Loe said:

I am thinking of building a truss dob from my DS 16 inch scope.
Where can you get inexpensive tubes for a truss dob?

Thanks

You could try these and see if they can help you:
http://dobstuff.com/
or
http://www.astrosystems.biz/

I think it's going to be a mixed bag, some will be good while others, particularly in the larger sizes will be less so. I've seen several reports that the 16" sizes have problems with their figures, with one report at 75%.

I had an opportunity while up at Mt Pinos several months ago to view through a newly acquired 24 F3.3 Hubble optics ultralight scope. This isn't mine but the owner is a seasoned observer and deploys very nice equipment while observing.
First, the optics were not stock but rather a custom set from Kennedy. Diffraction patterns were identical inside and outside of focus without evidence of under-correction. We were running 2500X on the cat's eye nebula during periods of excellent seeing and transparency with an associated decent level of darkness at a SQM level of 21.53 on two different units.
Second, on the structure, two major bugs were apparent: the DSCs didn't work and the structure "slipped" a bit during certain orientations, similar to a balance issue although that wasn't evidently the issue. Knowing the owner, I'm sure he'll get it corrected with due diligence. Other than that, the scope is a pleasure to view through and if you haven't seen what a large aperture ultrafast newt can do, let me say that it takes the observing experience to a whole new level. It's nothing like viewing through a plethora of standard 25" dobs out there or even 28" models that have a soda straw view with a wide-angle eyepiece. It's in a class all by itself and the field of view with it's associated level of brightness on DSOs is incredible. It's like going from a Huygen's eyepiece to a Nagler. I didn't feel the need to view through a night vision ocular with this scope. It's that good.
PS I've taken a break from the AM for awhile due to work and related issues but it's nice to be back!

Nice looking scope! Who does the optics for these?

You can get one of these and they're easy to use: https://optcorp.com/products/gerd-neumann-10mm-ronchi-eyepiece-10-101-150

Originally Posted by Jeff Lovaasen

Thanks, I never heard of these. I just bought one

It should work quite well. You can also enhance its sensitivity by placing it in a barlow lens. 

Originally Posted by Jeff Lovaasen

Rod Kaufman
It should work quite well. You can also enhance its sensitivity by placing it in a barlow lens. 
What about a powermate

You can use a powermate, 2X to 2.5X range.

Interesting article on where predatory lenders do their hunting:
http://www.csun.edu/ua/publicrelations/press_releases/Spring08/paydaylenders.html
I wonder how that shapes up with predatory mortgage lenders...