Mike
I just found this.This was a user review on the listing for this device on the OPT web site
http://www.optcorp.com/product.aspx?pid=778&tb=8 (scroll down). Is your LX90 an ACF or R ?.
Great for the Money But Needs to be used on a Old Style SCT and not ACF or HD Telescopes.
First of all this accessory is not desgined to be used on a ACF or EdgeHD Telescope. These scopes already have either a field flattener installed in the baffle tude or have a other type of field flattener incorporated into the optical train. Now if this accessory did not have the Flattener then it will work on these types of scopes. Again its not fair to judge it on the basis of being used on a ACF or EdgeHD scope since they already have field flatteners in them this device over corrects and causes optical defects.