Konica 55mm 3.5 Macro Lensgreenspun.com : LUSENET : Konica 35mm SLRs : One Thread
I have just acquired a Konica 55mm 3.5 macro lens. It did not come with a 1:1 extension tube. I have a 2X teleconverter which appears to do the same thing as the extension tube, however.
The telecoverter is a Vivitar for the Konica.
Will the extension tube give better results?
-- Anonymous, November 03, 1998
A 2X teleconverter doubles the focal length of the lens, at the expense of losing 2 f/stops in light transmission and some degree of sharpness - particularly toward the edges of the picture.
Teleconverters are particularly useful when attached to something like a 50mm f/1.7 lens, which effectively changes it to a 100mm f/4 which is quite useful in portraiture. However when a teleconverter is attached to the 55mm f/3.5 macro, the 2 f/stops of light loss result in an effective maximum aperture which is halfway inbetween f/5.6 and f/8 - which may cause the viewfinder to be too dark for accurate focusing in close-up photography. The dark viewing image, combined with the inherent loss of sharpness caused by the teleconverter make this device less than ideal for macro applications.
The matched, automatic extension tube for the 55mm f/3.5 macro lens is a hollow tube - with no glass elements inside. Consequently, there is no noticeable loss of sharpness. The 55mm f/3.5 macro lens focuses down to a 1:2 reproduction ratio without the tube, which is 1/2 life size. The extension tube allows moving the lens closer to the subject, to achieve a life-size 1:1 reproduction ratio. However, the lens extension caused by mounting the tube causes a light transmission loss of 1 f/stop. But this 1 f/stop of light loss is still better than the 2 f/stops of light loss caused by the 2X teleconverter, in addition to the much sharper image quality provided by the extension tube.
By the way, your macro lens has a small, chrome switch on the side marked "M" and "EE." The EE position should be used when you are basing the exposure on the camera's internal light meter, and the lens aperture ring is set to the auto-exposure position. The EE position will normally be used when you are shooting with available light, or hot lights. The "M" switch setting should be used when the subject is illuminated by electronic flash, and the camera's internal light meter is ineffective - requiring exposure determination with calculations or a flash meter. When the switch is in the "M" position, a mechanical linkage connects the diaphram with the focusing helicoid. As the lens is extended for closer focusing, the diaphram opens automatically to the degree necessary to compensate for the light loss. As a practical matter, this allows you to set the aperture recommended by a flash meter - without any additional calculations of light loss caused by lens extension.
Actually, the "M" position should be used anytime the exposure is not based on the camera's internal light meter. Examples would be when using a hand-held incident light meter, the "Sunny 16" Rule, or any other means.
-- Anonymous, November 04, 1998
Hal: I notice that E-Bay (are you familiar with this on-line auction) has a macro-lens adapter on auction, closing Mon evening (11/16). It is currently bid at $26+ if you are interested. It will give you a focussing capability to 1:1.
-- Anonymous, November 14, 1998