hkr4627@acf4.UUCP (Hedley K. J. Rainnie) (04/19/85)
Since I have no particular interest in Leica Rangefinder equipment, this question is out of idle curiosity. Why is it that Leica has the only f/1 lens I've ever heard of? And why don't they make it for their SLR line? The best anyone else seems to be able to do is f/1.2. -r-
jjd@bbnccv.UUCP (James J. Dempsey) (04/21/85)
> Why is it that Leica has the only f/1 lens I've ever heard of? And why > don't they make it for their SLR line? > > The best anyone else seems to be able to do is f/1.2. Cannon used to make a f/0.95 50mm lens for their rangefinder cameras back in the 1950s. --Jim Dempsey--
recais@mhuxv.UUCP (CAIS) (04/22/85)
> Why is it that Leica has the only f/1 lens I've ever heard of? And why > don't they make it for their SLR line? > > The best anyone else seems to be able to do is f/1.2. Nikon also made a superspeed lens for their rangefinders back in the late 50's. It was a 50mm f1.1 nine-element design. Zunow had a similar lens (available in Leica screw mount as well). The Canon 50mm f0.95 made its debut with the Canon 7 rangefinder in the early 60's. It has seven elements. These lenses were mainly for publicity and prestige and aimed at the photo journalist. Canon always upped the ante on competing Nikon RF lenses in an attempt to be number one. These lenses are not very practical. They are massive and heavy, with residual abberations compounded by the large aperture. The Canon lens has significant flare and field curvature. The contemporary Leica 50mm f1 is reported to vignette markedly. The use of aspheric elements can help but the manufacturing cost does not justify the extremely limited market. I have used the Nikon f1.1 and would choose the f1.4 any time image quality is a consideration. The depth of field of these high speed lenses wide open is vanishingly small at close distances. In practical terms flare reduces the working aperture (T-stop) below the marked value. The bottom line seems to be that cost, weight, and optical limitations do not justify the extra half stop in speed over a f1.2.
drraymond@watdaisy.UUCP (Darrell Raymond) (04/22/85)
There are a couple of good reasons for restricting f/1 lenses to rangefinders. The first is focusing accuracy. Depth of field at f/1 is practically nil; you really need the accuracy of the rangefinder, especially since you're bound to be shooting in low light conditions. The second is sheer size. A Noctilux is about twice the size of a standard Summicron; try to imagine the reflex Summicron twice as big as it is now. Mind you, the real reason in the case of Leitz is just that they like to be ornery - look how long it took to construct a decent M series camera with meter. Anybody out there own an M6? I'd be interested in hearing any anecdotes about it.
herbie@watdcsu.UUCP (Herb Chong [DCS]) (04/22/85)
In article <232@bbnccv.UUCP> jjd@bbnccv.UUCP (James J. Dempsey) writes: >> Why is it that Leica has the only f/1 lens I've ever heard of? And why >> don't they make it for their SLR line? >> >> The best anyone else seems to be able to do is f/1.2. > >Cannon used to make a f/0.95 50mm lens for their rangefinder cameras >back in the 1950s. > > --Jim Dempsey-- i'm pretty sure nikon made a few like a 24/0.8 or something like that. i know Contax made a 200/0.07, but it was really a sniper-scope so B&W was all you could really shoot and resolution was marginal for photographic work. as a surveillance lens system, it was great. anyway, all lenses that are faster than 1.2 are very expensive, heavy, and have a limited market. it's much harder to keep distortions under control at wide apertures and flare becomes a problem. as a fan of available light shooting, i try to keep up-to-date on things like fast film and high speed lenses. BTW, it's Canon. speaking of high speed films, has anyone ever used Kodak 2485 High Speed Recording film with Kodak 951(?) developer? this is NOT 2475 Recording Film that you can sometimes find in camera stores. with the 2485/951 combination, an EI of 8000 can be used and a negative with full density range of about 1.00 and normal contrast can be obtained. however, $$$, and hard as hell to find. i have been told it only comes in 35mm/150ft rolls. Herb Chong... I'm user-friendly -- I don't byte, I nybble.... UUCP: {decvax|utzoo|ihnp4|allegra|clyde}!watmath!water!watdcsu!herbie CSNET: herbie%watdcsu@waterloo.csnet ARPA: herbie%watdcsu%waterloo.csnet@csnet-relay.arpa NETNORTH, BITNET, EARN: herbie@watdcs, herbie@watdcsu
darrelj@sdcrdcf.UUCP (Darrel VanBuer) (04/23/85)
The few f/1 lenses I've seen or heard of (excluding things like fresnel
burning lenses which don't need high resolution) were all rangefinder lenses
(e.g. Leica, Canon, maybe Nikon) and normal focal length 35 mm lenses.
It will be a long time before any of these is nontrue, due to physical and
optical constraints (and even mount constraints).
SLRs are a real lens design challenge because space for the mirror means an
inverted telescope deisgn for lenses shorter than 80 mm (sort of a wide
angle lens way out front with a magnifier behind it to get the image to the
right size)--see problems with wide angles below).
Ultrafast telescopic lenses simply need HUGE elements (thus expensive: a
Nikon 200 f2 costs $1700)--doable but not marketable.
Fast wide angles cause you to run into problems with a conflict between
adequate diameter and high curature elements (you can't make a 3 inch lens
blank with a 1 inch radius of curvature).
Extremes in lens design always make trade-offs harder--large, high curvature
elements really strain efforts to control various aberations to give an
acceptibly sharp lens.
Finally, rising expectations for lens quality and rising film speeds for a
given sharpness since the days of the rangefinder have made that last half
stop extra speed just not worth the costs.
--
Darrel J. Van Buer, PhD
System Development Corp.
2500 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
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