This is a review done a long time ago on Cloudy Nights. We used stainless steel at the time for our eyepiece barrels making them very hard to thread for filters. Shortly latter we went to Aluminum and solved the problem. The review reflects this. In the concluding comments it showed the superior optical quality of the Siebert Optics standards over the Orion Expanse series. 

Paste the link below into your address command line.

http://www.cloudynights.com/item.php?item_id=261