of smaller Series I 35.5mm close tolerance VMC filters. In this lens, filters are placed behind the lens in the T-mount, thus allowing the use. Exposure is controlled by camera shutter speed and the use of neutral density filters.
As with all mirror telephoto lenses, the Vivitar Series I 600mm f8 is a fixed aperture lens. This " hot spot" results from a difference in illumination between axis and corner of 50% or more.īut in the Series I solid catadioptric lens fall-off has been reduced to less than 30%, the equivalent of about 112. The troublesome "hot spot" present in conventional mirror lenses is almost entirely absent in the Vivi tar Series I 600mm. This near-solid construction also makes the optical alignment highly resistant to damage from impact. As all the optical elements share similar temperature coefficients, the lens is temperature stable even in extreme climates. In the 600mm f8, spherically shaped elements are pieced together to form what is a virtually solid element. These lenses are also susceptible to severe mis-alignment caused by minor shocks and vibrations. Temperature variants often create serious optical alignment anomalies, decreasing sharpness. In conventional designs, the optical ] groups of the lens are separated by large air spaces. (A 600mm lens would require 1/500 second or faster shutter speed.) Stability has been another major problem in catadioptric lenses. The photographer can safely violate the rule for normal telephoto lenses that minimum shutter speed should approximate focal length in hand held shooting. Highly acceptable hand-held shots at relatively slow shutter speeds are entirely possible.
The short physical length of this lens helps to lessen the effect of minor in-camera vibrations such as mirror bounce on image sharpness. This compares with a 1.2 to 1 ratio for traditional non-mirror telephoto lenses and about four-to-one for previous reflex lenses. The extreme Series I 600mm so lid catadioptriC lens compactness of this lens is attributed to the achievement of a seven-to-one ratio between focal length and barrel length. The optical design of the aspherical 600mm solid catadioptric lens is derived from the Cassegrain telescope objective used extensively in astronomical work. it offers the photographer extreme compactness, inherent environmental stability, and superior relative illumination characteristics that have until now been unattainable in long focal length reflex lens for 35mm photography. This lens represents three major advances in catadioptric lens design. Vivitar Series 1 600mm f8 solid catadioptric telephoto lens For the older eyes amongst us, here is a rough scan of the text:
0 kommentar(er)
