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Ok, some photos. Had it out on Friday night for some testing. Some very good points I noticed, and some disappointing things.
Good points. The focuser is beautiful, but you'd expect that from a 3" FeatherTouch. Came in a nice case, and the scope itself is just solid and feels like quality. Quite weighty for it's size. First thing I noticed was the focusing between filter changes. With the ED80 there was quite a bit of shift and had to refocus noticeably. With the TMB92SS, I checked focus between filter changes but the shift was nominal. I understand this is because it's obviously a much better apo, so better colour control.
Disappointments. First thing I noticed was the way the focuser is connected to the OTA. It seems to slip/creep rotationally. It's connected via 3 nylon tipped screws that go into a groove the runs around the focuser piece. No matter how tight I did them up, with finder guider in the bracket the whole focuser crept around with the offset load. I ended up having to put the finder guider on the top dovetail so the focuser wasn't eccentrically loaded. I need to get to the bottom of this, whether it's a FeatherTouch or scope issue. See photos below.
Second was the field flatness. I was using the Orion Flattener I'd been using with my ED80 with some success (although minor eggy stars still in one corner). The TMB92SS fits exactly within the specs of the Orion Flatteners advertised range of effectiveness. But the field was not flattened. I need to do more testing to see if it's the scope, flattener, spacing of camera, or maybe sensor tilt? Due to operator idiocy I did not get test images with just camera and no flattener. Duh.
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