Mars & Jupiter in the APM ED 152
I observed from 1015-1145 UTC, at 1000:
Temperature 23°F (-5°C)
Wind Speed Calm
Dewpoint 15°F (-9°C)
SEEING = 7 / 10 [mid-level haze]
First: No CA or fringing on any object from 24x to 400x. I had my excellent 1971 Criterion RV-6 Dynascope for direct comparisons -- both scopes have a 1200mm FL, which makes setting equivalent magnifications easy. In the RV-6, Jupiter's zones are a pure white; in the 152, they're an off-white (a hint of gray). Seeing varied with a mottled layer of mid-level moisture coming in from the west, and I adjusted the mag accordingly. I used a high-quality spectros PL 5 @ 240x most often; but around 11Z, I was able to use the PL 7.5 + GSO APO 2.5x Barlow for 400x (67x / inch), and see 1 large & 2 small whitish ovals in the NEB -- like a trio of pearls. Even at 240x I saw more fine detail than I could sketch.
The Galileans in this APO are 4 tiny real worlds. Color & brightness differences were obvious at 120x. At 400x, Ganymede had at least 3 different colors / albedo effects, while Callisto remained a faint uniform blue-gray. Once Jupiter is better placed, I'll be able to make a serious study of these two at least.
Mars offered only one or two surface features, but the disk color was very similar between the two scopes.
Functionally, I have no complaints with the APM 152. Focuser rotation was as smooth at 23F as at warmer temperatures. I had thick gloves on, but had no problem snapping to a sharp focus at every magnification. The views were overall superior to the RV-6; and, best I can recall, are sharper than those in the 6" F20 Tinsley Cassegrain. The Meade StarFinder mount had no problems balancing, moving, and tracking at up to 400x.
If you're thinking about buying a Big APO, you won't regret getting the APM 152 -- it's a high-performing bargain!
Edited by Bomber Bob, 06 January 2018 - 08:08 AM.