I had wondered for years how a Vivitar 2x Macro Focusing Teleconverter would work in practice. I finally found one for sale for $10 at a thrift store, but at that price I wasn’t that interested. It would fit a Minolta SLR—an older one pre-autofocus—so I knew I would have to really look through my collection to find a camera that would accept it. It so happened that particular thrift store clears out its inventory twice a year by selling literally everything at half price. I returned during the seasonal sale and managed to snap the Teleconverter up for $5.
(left—camera-end of 2x converter)
It is surprisingly hefty, weighing close to 300 grams (with front and back caps on). It has 7-elements so qualifies as one of the higher quality teleconverters (some teleconverters had 4-elements). It has two scales, one in blue and one in white. The white is valid when the 50 mm camera lens is kept set at it’s infinity setting. The blue scale refers to the normal lens being set at its closest setting of .45 M. The blue setting is the only way the shooting ratio gets down to 1:1. You are shooting the area of a 35 mm frame at 1:1 at about 150 cm from the front of the lens to the subject. While this doesn’t sound like a big advantage it really is with some subjects.
(Right—Lens end of 2x converter)
Which brings us to the other major advantage of using the teleconverter. It doubles the focal length of your 50 mm lens to 100 mm. You also lose two stops of light gathering. So the 50 mm normal lens with an aperture of f/1.7 used wide open becomes a 100 mm f/4. Of course shooting a macro lens wide open is not normally the best way to capture edge or corner sharpness.
This devolves even further, as some lenses are designed for “flat-field”. If you collect and shoot stamps or coins and bills, you might have better results shooting with a dedicated macro lens. Most of the rest of the work-arounds—close-up lenses, extension tubes and bellows—used with regular lenses suffer some loss of sharpness in the corners.
This Vivitar teleconverter sold for $80 new. It was cheaper than an auto-bellows, probably in the same region as a set of three auto-extension tubes and a really cheap 2x extender.
It is calibrated for reproduction ratio, which can be extremely important. It gives you a really handy portrait lens with just your normal lens (edge sharpness being poor being a bit of an advantage in portraits). It gives greater range doubling any zoom or telephoto you might have—keeping in mind that two stop loss of light can make focussing difficult and your available top shutter speed falling along with the magnification doubling may give you sharpness results below what is acceptable.
And that is something many have noted. Often a teleconverter gives poorer results than simply magnifying the original lens’s results. For those using negative film blowing a negative up—despite larger grain—stays sharper than the teleconverter’s results. Of course those shooting slides might convince themselves the slight sharpness loss is acceptable.
If one had several of these 2x Macro converters it might be interesting to simply punch the 2x optics out of one and use the mount to keep the aperture levers working while gaining a rigid variable extension tube.
You will end up working pretty close to your subject, but all the original 50 mm lense’s sharpness will remain.
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