My 3 identical frames make initial alignment a snap. The OTA took the place of the middle frame, so I had to get it up to the center line between the end frames. Used a laser to check alignment, then ran the tests.
I check the patterns inside focus, at focus, and outside focus, with 3 / 4 / 5 vertical bars. BIF: I measured Focal Length at 1215mm +/- 5mm. I made photos to compare with DPAC patterns from my other refractors. No, I'm not posting them. Last time I did that, spent 2/3s of the thread being told I can't operate a camera, so no repeat of that experience.
Overall, patterns inside & outside focus were identical, which agrees with my star tests. Vertical bars in the 152 are jet black & narrow, but not quite as fine as my Vixen 80 fluorite or my Swift 50 F14. Bars looked most like those in my Royal 76mm F15, which is a fantastic lens -- about my best traditional long achromatic. It stays sharp at 80x per inch in 8 seeing.
I saw no curvature in the 4 or 5 bars, which I have seen with other lenses. At focus, I saw no major deformities.
This lens is at the higher end of the scale in my collection, which surprised me, as I have others that cost a lot more per inch of aperture.
Edited by Bomber Bob, 22 September 2018 - 02:23 PM.
