The Ortho's I have are the 10mm and 7mm Takahashi. Very expensive...about $170 per EP. Very well made and they perform great. Brandon I hear also make a little cheaper Ortho, but not sure.

The plossl vs. Kellner (i.e. MA/SMA) will exhibit a little better field of view and better eye-relief. Most plossls have 4 to 5 elements (depending on what brand and size) whereas MA/Kellners have 2 to 3.

Plossls are considered the all-purpose EP that is a good inexpensive go-between for any scope. Plossls come in many varieties such as the extra element and coatings. Erfles are somewhat better in some cases than plossls, but can be more expensive. Orthos seem to be making a slight comeback is some regards to their quality of manufacture. If and when I buy a scope that comes with Kellners, I always replace them with plossls or better. I actually keep the Kellners for 2 reasons: 1. for my sidewalk and star-party observations of the moon 2. Daytime terrain viewing. I always suggest getting at least a plossl EP when having a new scope. You can always upgrade later if you wish. Go to the website below, and scan down until you see the EP section. It explains all of the EP's there are and what they can do. Good Luck!!

http://home.kendra.com/comet61/TELESCOPE/buying.htm

• Orion Sirius Plossls - barnard - April 9, 2003 - 18:04 UTC