New Lens, New Moon

Taken with NIKKOR 70-300mm Zoom, enlarged and sharpened.

I was excited to see how a moon shot would turn out with the Samyang/Phoenix 500mm cat lens, and tonight was clear enough to give it a try.

Moon, courtesy Samyang/Phoenix 500mm f/8 Reflex Lens, native resolution.

Same as above, enlarged and sharpened.

The second photo is the original, un-enhanced version, shot handheld at 1/1000 sec. the third photo is the same image enlarged to the size of the last moon shot I took with the NIKKOR 70-300mm refractive zoom, and sharpened just a bit. The first image is the NIKKOR 70-300mm refractive image.

The experience of taking the photo was most enjoyable. The image appeared quite large in the viewfinder, and once it was focused, there was lots of detail. I took a few shots and chimped; this was the third. The fourth was no better. It was fairly easy to focus, but because we’re going for the absolute maximum resolution here, it had to be DEAD on.

So, I put the camera on a tripod (more to free my hands than anything else) and used Live View to zoom in tight for focusing. It helped a little, but not as much as you’d think. Then, I set the camera to self-timer mode, steadied it, and pressed the shutter release. I did this many times in an attempt to improve over the original (third) image. I never did. Then, clouds started drifting in front of the moon, and I called it a night.

So, this is what I have learned:

Live View has an automatic gain that sets the display brightness, and with such a bright object against a jet black background, all detail was lost. So not much help there.

The tripod does virtually nothing if it’s not both very rigid and placed on the ground, not a deck.

At this magnification, everything works against you, including mirror slap, which is unavoidable in a camera of this class in which you can’t lock the mirror up. So while the image might have been as sharp as the refractive lens’, the additional magnification cancels it out.

But, overall I’m not unhappy with the results, because I know that there are still some technical issues to work out. And, if you look at both images straight out of the camera at their native size, the catadioptric image looks better, because it’s larger and therefore displays more detail. It’s only Photoshop trickery that makes the refractive image look better.

Armed with this knowledge, I’m betting that the 800mm f/8 catadioptric will yield an even better image. From what I’ve read, the other two Samyang catadioptric lenses, the 500mm f/6.3 and the 800mm f/8, are optically superior to the 500mm f/8, though not nearly as compact and well built. I think the 800mm would be well-suited for astronomy, and the 500mm f/8 good for terrestrial work. So, the 800mm is tentatively on my wish list.

What Would I Have Done Differently?
I would have used some sort of optical magnifier to help me focus instead of Live View. Once again, digital is not always the solution.

• I would have added some mass to the camera/tripod assembly to dampen out vibrations.
• I would have used the infrared remote to trigger the camera instead of the self timer.
• I would have placed the tripod on the ground.