celestron onyx (1 Viewer)

This looks like a serious piece of hardware at a bargain price:

http://www.optcorp.com/product.aspx?pid=8146

Does anybody have any firsthand knowledge of it?
Could it be turned into a useful backyard spotting scope?

There is a highly technical review of this scope in German here:

http://www.astro-foren.de/showthread.php?t=7887

This particular specimen has defective optics, mainly from astigmatism and miscollimation. The important numbers are peak to valley wave front error of only a little better than 1/2 wave, RMS 1/16 wave and a strehl ratio of .86. Pretty miserable for a scope of this type. Some other specimens are probably better, some could be worse.

I'm afraid that's the problem with telescopes, especially inexpensive ones. The quality is highly variable from one sample to another.

willemjacobusse said:

This looks like a serious piece of hardware at a bargain price:

http://www.optcorp.com/product.aspx?pid=8146

Does anybody have any firsthand knowledge of it?
Could it be turned into a useful backyard spotting scope?

Click to expand...

Dave, There is some more information in this link. Like Henry says there can be some sample variations.

http://www.cloudynights.com/ubbthre...576/page/10/view/collapsed/sb/5/o/all/fpart/1

Regards,Steve

Dave I have one of the these C80ED, very nice scope. Not light weight and not short.I also have a WP 60mm Nikon 60mm Fieldscope.I use a mirror diagonal/reversed image with the 80ED, I have had this scope up to 100x during the daytime looking for CA and could not see any Chromatic Aberrations.

http://www.adorama.com/CN80ED.html

Steve

The trick to buying any scope is to make sure you don't wind up with a bad specimen. An "average" example of this scope would probably be a very good, but large and heavy spotting scope. If you don't already have them you will still need an erecting prism or mirror and an eyepiece. Be sure to avoid the low grade 45 degree Schmidt prisms (like the one attached to the C80ED in the Adorama link). Those ruin the image quality of any scope. Stick with a mirror diagonal like Steve uses or a diagonal prism (which may actually slightly improve the optics of a scope like this). Right and left will be reversed, but that's better than a poor image.