[Raymond]

Nice review, Mark.

I did a similar visual and photo review myself last week when I got one Celestron 80ED on loan from local dealer for testing. At roughly the same time, I got my purchaserd Orion 80ED (actually two OTAs, one for me and one for my friend).

Celestron rightly classifies their 80ED as spotting scope, since their OTA is a shorter than Orion's OTA. Therefore, even with Celestron's supplied T-adapter, you can just reach focus when the R&P focuser is completely racked out without any space for you try focus back and forth. You need an extension tube (I use Kenko extension tube set, but other extension tube might fit as well). Orion OTA is longer and therefore focusing with their supplied T-adapter leaves more space for you to confirm focus.

While the defocus star on axis is concentric and very respectable, one thing I also notice in addition to your comments is that both Orion and Celestron 80ED show some elongation of defocused (both in or out of focus) stars near the edge, ie coma around the corners. At least for my Orion 80ED, the coma is a bit slightly better than Celestron but the difference is not very big. One probably needs a coma corrector (I have TV Paracor on hand and Baader Celestron MPCC on order) but I have not yet tried them in the field for astrophotography.

Another astro friend and I tried Celestron 80ED with Canon 300D last week on M42 and other DSOs. The stars were pin-point for most of the central portion of the image and CA was very acceptable and better than expected for this price-range. However, you need longer exposure for F7.5. I have not tried focal reducer but believe that either AP or TV reducers will help to shorten the exposure time.

What both Orion and Celestron 80ED excel is through terrestial viewing with miminal CA. View is crisp and pleasing. There will be some yellow/green halo when you look at very bright objects such as street Mercury lamps, more noticeable when you view bright objects and move your eyes around slightly. But you don't look at bright objects that often.

Clear skies !

Raymond Tse, Hong Kong.
Orion 80ED,
Apogee RA-88-SA
TEC140(on order)
CZ12.5-inch Dob