Splittin' Hairs - J50 vs. FC-50
BLUF: A few of the faintest stars in the FC-50 eluded the J50; otherwise, the star tests, color tests, & double stars were very close - both 50's at the same magnifications.
Used TAK prism diagonals in both - 1.25" in the FC-50, .965" in the J50; spectros .965" eyepieces, except I had to use that 1950s ASC KE 30 to get the J50 to 20x.
Seeing tonight was 8 / 10; surface winds variable at 5 knots; some moisture at the mid-level.
Aligning the J50 OTA with the FC-50 OTA was tedious & annoying without motorized tracking. The Swing Arm is like a crude AZ mount; and, you have to use an Allen wrench to adjust & lock the altitude, so naturally the star centered in the FC-50 drifts off... I settled for the target just left / south of center for the FC-50, and just right / north for the J50 with both scopes at 80x.
Betelgeuse & Capella: I expected the J50 to have more orange/red than the FC-50. Nope. AF / IF / OF at 80x made no difference. Procyon: White with a hint of yellow in both. Regulus: Brilliant blue-white in both. As for fainter stars, both fracs showed the orange stars in M35 as orange - no observable difference. Castor & Algieba: Identical Figure 8s at 80x - though the stars appeared slightly brighter in the FC-50.
So far, the J50's performance reminds me of the Swift 838. I'll have to go back and read my SxS between the 838 & FC-50. IIRC, the FC-50 pulled ahead with the Trapezium; and, significantly, with Jupiter & Saturn at 150x.
These tests have shown me that the J50 is worth building an OTA around; and, they give me a minimum standard to shoot for with that build. If it does this well attached to the end of a Towa, the OTA I make should be even better!
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Starting at 1030Z, the Duo delivered sharp views of the morning planets in 8 / 10 seeing. C/V Turret on the FC-50, left the Tak .965" prism on the J50, and spectros .965" eyepieces.
Fair / 49°F (9°C)
Wind Speed Calm
Dewpoint 47°F (8°C)
Visibility 10.00 mi
Saturn & Jupiter: A ringed planet in both at 40x; sharper at 80x in the FC-50, and the J50's disk has a very subtle hint of gold rather than pure white. Ring shadow on the disk in both. Both showed Callisto emerging from behind Jupiter - a dim but tight nano-dot. Both showed 4 belts total, with the STB intermittent, and the NEB, NTB, & SEB persistent. FC-50 showed the edge of the GRS notch in the SEB -- couldn't quite break it out with the J50. I'll have to recheck this when the Jaegers is in its permanent OTA. With Barlows: FC-50 softened at 200x, J50 at 248x; both were sharp at 150x & 165x, respectively; though the J50 was dim, and took more effort to get the best focus. Jupiter's disk is paper white in the Tak, and light wheat in the J50. GSO 1.25" 2.5x APO in the Tak, and AO .965" 2x in the J50. Both showed the 3 Galileans as fine Airy Disks -- I used these to get best focus.
Edited by Bomber Bob, 12 April 2021 - 08:09 AM.