Looking for Recommendations on a 2" Diagonal

Hello Everyone,
I’ve decided to upgrade to a wider field of view in my 8” SCT by going with 2 inch eyepieces (Orion Q70s, Moonfish, Garrett SWAs, Orion Status, etc.). However before I purchase any 2” eyepieces, I need a 2” diagonal; thus the purposed of this post. Also worth noting is that I strictly an observer, I do not image (maybe in the future, but not now).

I want to go with something in the high-reflectivity range, 95% with a budget of around $150.00 (however the lower purchase price the more I have to spend in eyepieces).

So my first question is in regards to dielectric coatings, will my eyes be able to see (versus a CCD chip capture) the difference between a 96% XLT coated diagonal versus a 99% dielectric diagonal?

Is there really a durability difference in high-reflectivity ‘non-dielectric’ diagonals versus dielectric diagonals versus quartz diagonals?

Lastly, there are some features that I’m not sure about. Is it worth getting a “SCT” diagonal (i.e. – it screws on to the back of the scope) versus using an adaptor? I’ve seen a few non-SCT diagonal with a flared tube that keeps the diagonal from falling off the back of scope should the set screw loosen. However these diagonal do require an additional piece of hardware (adaptor).

Based on my research, I’ve come up with a short list of diagonals. Any feedback you could provide would be most appreciated and of course feel free to add any additional recommendations:

OPT - 2" Deluxe Dielectric Mirror Diagonal with SCT Thread (http://www.optcorp.com/product.aspx?pid=105-147-152-7751)

Celestron - 2" SCT XLT Diagonal (http://www.buytelescopes.com/product.asp?t=54&pid=11053&m=)

OPT - 2" SCT Quartz Dielectric Diagonal (http://www.optcorp.com/product.aspx?pid=105-147-152-8597)

Astronomy Technologies 2" 99% reflectivity dielectric mirror diagonal for SCTs (http://www.astronomics.com/main/product.asp/catalog_name/Astronomics/category_name/FMQNRTR9001K8HFE68PKXTPEC0/product_id/AT2SD)

William Optics - 2" Carbon Fiber Dielectric Diagonal with Free SCT Adapter (http://www.buytelescopes.com/product.asp?t=54&pid=11467&m=)

Many thanks!
-Mike

Michael Keefe said:

Hello Everyone,
I’ve decided to upgrade to a wider field of view in my 8” SCT by going with 2 inch eyepieces (Orion Q70s, Moonfish, Garrett SWAs, Orion Status, etc.). However before I purchase any 2” eyepieces, I need a 2” diagonal; thus the purposed of this post. Also worth noting is that I strictly an observer, I do not image (maybe in the future, but not now).
!
-Mike

Do you use your scope in alt-az or EQ mode? If in alt-az, an SCT diagonal is fine. If you use it in EQ, a refractor diagonal is easier to adjust viewing angle wise.

You've got some good choices, but none would be _my_ choices.

What do I like?

For a little: The William Optics carbon fiber dielectric job.

For deeper pockets: The Denkmeier Powerswitch diagonal. IMHO this is the bee's knees, the CAT's meow, the ne plus ultra...the ULTIMATE diagonal!

8)

And you might want to consider an a less expensive alternative:
http://www.owlastronomy.com/kowldiag.htm

Mike: Since Uncle Rod didn't mention it, I will throw this out there...

Have you considered a focal reducer? In particular the Celestron F/6.3 reducer corrector?

This allows you to use your same eyepieces but achieve significantly wider field of view. Used ones go for around $100 or so. I have one for my C-5, it works.

Uncle Rod can fill you in on the particulars, I think he has been know to use one.

Jon