arathi-sridhar [EMAIL PROTECTED] wrote: http://www.rugift.com/photocameras/pentax_cameras_lenses.htm
Wow, I knew about the Rubinars, and of course the Zenitars, but I had no idea that the Rubinar mirror lenses are available in K mount. Not that it makes a big difference, I suppose: You can't "stop down" a mirror lens, so you're not losing anything when you buy an M42 version and use a screwmount-to-K adapter. These are the best Rubinar prices I have ever seen. You can do a little better on the Zenitars on Ebay and other dealers. Rubinar mirror lenses do claim bragging rights in the brightness department. Be aware, however, that f/5.6 in a mirror lens may not yield as fast a shutter speed as f/5.6 in an all-optical design. Or so I have read. I don't know anything about the Rubinar 300/4.5, but I think you'd be happier if you could afford a used Sigma APO Macro 300/4. They sell used for about $300 on U.S. Ebay. I have a Ricoh XR Rikenon 300/4.5K that I like very much, but I've seen only three for sale in five years. It sells for about $250. The Rubinar 500/5.6 weighs either 1200 or 1600 grams; I've seen both figures. Here are my collected comments on the Rubinar 500/5.6, unedited: "The Rubinar 500mm/5.6 is huge with a diameter of 105mm or something like that all the way to the lens mount." " On Contax site: http://www.cdegroot.com/archives/yashicacontax-slr/199805/msg00030.html: "Hello Michael, If you wouldn't fix on Zeiss optics, there is a good *new* inexpensive 500/5.6 mirror lens. It's a M42 mount "MC Rubinar 5.6/500 Macro", a Russian lens, with an excellent optic quality. As an M42-Contax /Yashica mount adaptor will be easily available, you can use it mounted on your RTS without any inconveniences. I don't know the prices of it in other countries, we can buy it for 250-300 USD in Japan.very heavy (1.6kg), bulky and roughly made lens. But seems to produce photographs of acceptable quality. --Yoshihiko Takinami, Osaka, Japan ([EMAIL PROTECTED]) Dirty cheap for an apochromatic ;-) supertele. Mathias was very pleased with the quality of the 500mm/5.6, he rated his sample higher than an Sigma 400mm/5.6 APO. What is very interesting to me is mirror 500mm/5,6. They sell it with adaptall T2 for various camera brands. Thomas Jakubowski, October 22, 1999; 05:09 P.M. Eastern: "Peter, I have an optics background, so making my most recent selection of a lens was based on cold physics. I purchased a mirror lens (Schmidt_Cassegrain). 500 mm. $250. Here's what I didn't get: 1. chromatic and spherical aberration - reflective optics by definition do not carry the same baggage as refractive optics. 2. bulk and length: the lens weighs in at about 10 ounces, and is about 6 inches long. there's no need to counterbalance a camera with 20 inches of lens while sitting on a tripod. Believe me, this lens was easy to carry and to change. 3. Poor Photographs: By definition, these lenses have only a small depth of field. For example, the Promaster I purchased has only about = inch at 12 feet. This could be considered a (fatal) flaw, but I used it to my advantage. I do flower photography, and was able to come up with shots as never before. Flower is in focus, foreground and background completely out of focus, and now I have prize-winning photos that started out as mere photographic studies. 4. Poorly lit/exposed photos: This particular model has a diameter of 3.5 in for the primary mirror. That alone pulls in plenty of light. Caveats: This lens has a fixed focal length, which means that you cannot use a camera body that offers autofocus. It also means that you control your exposure by modifying exposure time. My experience has been with an Olympus OM-1 camera. Once I mastered the focusing of this camera/lens combination, I produced photos so impressive that my wife actually wants them hanging on the living room walls!" - Bob Atkins , October 22, 1999; 06:07 P.M. Eastern: "Here's also what you got. You got a slow lens. You got a manual focus lens. You got a lens with a fixed single aperture. You got a lens with greatly reduced MTF in the critical 10-70 lp/mm range due to the central obstruction inherent in the design. You got a lens that renders out of focus highlights as "donuts" and generally has poor "bokeh" (search the Q&A forum if you're not familar with that term). You probably got a lens with a curved field and off axis coma too. While mirror lenses don't suffer from chromatic aberrations, they do suffer from all the other aberrations common to refractive lenses to a greater or lesser extent. For $250, you don't have too much to lose, and if you are happy with the images, that's great, but mirror lenses aren't really an alternative for serious photographers needing high technical quality images, images of moving subjects (MF tracking can be tricky), or images on slow film (too slow in evening/morning light). They have their place (I actually own one myself), such as when hiking long distances when weight REALLY matters, but they're no substitute for a refractive optics camera lens when all around performance is an issue. If you can live with the limitations they do fill a need for some people. The one plus of most mirror lenses is that they focus much closer than similar focal length referactive lenses (though their optical performance may drop when close focused). BTW the DOF issue is common to all lenses. DOF is the same for a 500mm mirror lens as for a 500mm refractive lens. In fact since most refractive lenses are faster than mirror lenses, they have LESS DOF when used wide open and focused at the same distance. I've also seen some interesting (non-nature) work done with a 500mm mirror lens with a diffusing filter attached. "Arty" sort of stuff where technical image quality isn't really an issue." [EMAIL PROTECTED]
