New lens. A 55/1.2 XR Rikenon by Ricoh

Started Dec 17, 2017 | Discussions thread
Flat view
chris gunn
chris gunn Veteran Member • Posts: 8,606
New lens. A 55/1.2 XR Rikenon by Ricoh

It was going cheap and has no aperture mechanism.

Testing it for astro, it seems to have good sharpness and colour, and astonishingly, zero astigmatism!

It is the perfect lens? Well there's one major flaw, the most huge weird "Coma"/internal reflections. I'm guessing the missing interior parts have left some nice reflective surfaces. I'm thinking of asking a lens tech to spray some matt black paint in there.

I bought a 58-25mm step down ring (24mm aperture => f/2.3) to see how that affects things. It then gives orderly bar coma, which is almost fine for a panorama where mostly the center image portion is used.

Some samples:

5min 50s @ f2.3 (forget the sub time... 20s?) tracked with the Pentax Astrotracer (this is all done in one evening, along with some 300mm subjects).

From a time lapse, f/1.2 24min 15s, of 15s untracked. 101 subs! Crop of the LMC.

So much light, I was curious what secrets would be revealed.

From another time lapse, of Orion at f/1.2, 32min 48s integration! That's like 2.6hrs @ f2.8. (8s x 246) Enough light to bring out the Witch nebula?

Well, I can see her chin and nose.... I used the Sigma kappa with 3,3.

My hat off to all those who manage to capture her.

One more @ f/2.3, 24min of the SMC

-- hide signature --

-- Get a big lens and get closer™.

Flat view
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow