Iwerk
New Member
Posts: 36
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Post by Iwerk on Oct 22, 2006 22:38:18 GMT -5
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Post by Larry N. Bolch on Oct 23, 2006 1:18:53 GMT -5
I have a superb, but rarely used 600mm Vivitar Solid Cat, built by Perkin Elmer - the optical house who built the Hubble Space Telescope - and marketed by Vivitar. Unlike Hubble, it was sharp on arrival.  The problem with most mirror lenses is that they are extremely delicate, and even a slight bump or two can put them slightly out of alignment. Since they are so powerful, it really does not take much to make them worthless. The advantage of the Solid Cat is that instead of being filled with air, it is filled with solid optical glass. It could be used as a formidable weapon, and still take sharp pictures. The price is that it is extremely heavy. There is no diaphragm, so it is a fixed aperture - as are all mirror lenses. It is mathematically f-8.0, but in practice, nearly a full EV is lost as light passes through, so in effect it is close to being f-11. None the less, the depth of field is minute. Accuracy in focusing is vital at such focal lengths, and with such a dim view, it is pretty much useless in anything but full daylight. Compared to a 50mm "normal" lens, all camera movement is magnified by 12x. Thus a solid tripod - or a monopod and very fast film or a high ISO setting - is essential for sharpness. Hand-holding is pretty much out of the question. There is the combination of the weight, dim view and camera movement to make it very difficult to be steady enough to properly focus the beast. Off a sturdy tripod and with considerable patience it can be done. It is however, not a trivial task. Realize on a Nikon digital SLR, you have the cropping factor, so the lens in effect becomes a 900mm equivalent, with an 18x amplification of any vibration or motion. It has a "bokeh" that people tend to love or hate. Any out-of-focus highlight instead of being a pearly point, is a pearly donut! It strongly de-emphasizes perspective, and that was the sole reason for acquiring it. Doing a travel assignment, the editor specified at least one shot of Las Vegas signs absolutely filling the frame. No problem - it was as if they were spread over a flat wall. The assignment paid for the lens many times over, so no sweat in buying it. Since then, I have rarely found a use for it. If you are into photography of small birds, and have the patience to use the lens, it would probably be very good if focused on a feeder from a blind. Even so when focused on a small bird's eye, the tail is likely to be completely out of focus. If you do have the patience and the limitations don't get in your way, they are an economical way to get a whole lot of focal length for much less than a conventional super-telephoto lens. Just realize that they do require a lot of work and a high level of skill to use. Even with extreme care, many images will be culled. By the way, I once mentioned the lens in a forum, and there happened to be someone who had worked on it at Perkin Elmer. She assured me that the team that made it was very proud of it, and distanced themselves from the crew who botched the HST optics! Interesting perspective. It is a legendary lens, and how Vivitar happened to market it, is a bit of a mystery and wonder. |
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Post by natstek on Feb 10, 2007 18:31:05 GMT -5
You know people,
That Opteka lens looks an awful lot like a 300mm, f/5.6 mirror lens that I've had & used for over 15 years.
One thing to remember though, ALL catadioptric lenses are SOFT! and the background "Bookeh" will consist of "Donut-shaped" highlights. Other than that, they're wonderful. My 300mm takes 62mm front filters and fits in the palm of my hand!
Art Tafil
Knoxville, TN
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