Lens Spotlight: A50 Macro & 1.4x-S - Jason Doss

Lens Spotlight

smc Pentax-A 50mm f/2.8 Macro

& Converter-A 1.4x-S


The Pentax SMC-A 50mm f/2.8 Macro is, of course, all manual with an aperture ring and manual focus ring. A-series lenses have an A setting on the aperture ring which enables aperture control on the camera.  Macro lenses with a normal focal length (50mm or so) tend only to magnify to half life size, which means the smallest field of view is only 48mm x 72mm.  


Macro lenses do best at close distances and have optics with minimized distortion. This lens sports a reasonably fast f/2.8 maximum.  The fast aperture allows greater focus precision, however most macro photos are typically done stopped down to f/11 or smaller.   This lens is one stop faster than its M-series counterpart, and in fact there is a slower f/4 A-series 50mm Macro which I think was a holdover from the M-series.  


The lens is 220g (0.5#) and, focused at infinity, 40mm long (1.6 inches) and has 49mm filter threads. There are markings on the lens to indicate the magnification ratio. This macro lens has recessed front elements, therefore a lens hood is not required.

In my collection, I work thru lenses in a random order, and I treat the addition of teleconverters as a separate lens. So, here, the A50 Macro is paired with the 1.4x Pentax teleconverter of the day, which was the Converter A 1.4x-S. The teleconverter adds 0.85 inches and 5.1 ounces to the package. The fit is tight and comfortable. Magnification is increased by 1.4x without decreasing the minimum focus distance. The combination behaves as a 70mm f/4 lens with 3/4 life size magnification.

On display this time are three macro images taken at 70mm, with flash, and near the house.  The boys and went in search of subjects, armed with a shoe-mounted flash, hoping to highlight the closeup performance of this combo.  At top, we see berries growing on the stalk of an American beautyberry bush.  These grow in dense clusters at the base of each pair of leaves, and are intensely purple.  They are supposed to be easy to grow, and I'm going to test that... I've gone around my place tossing berries alongside the road, and hope to see the road lined with beautyberries next year.


A katydid poses on the outer window sash, and was a good sport tolerating a very close-up shot with flash to boot.  And on the right, we have a long-snout butterfly who also co-operated with my photography attempts.  Each animal posed for at least three shots, and these were the best of each series.


Flash photography and macro go hand-in-hand.  It's the best way to combine hand-held photography with low light and small apertures.  Plus, since the flash impulse is microseconds, then unless combined with long shutter speeds, that kind of illumination will often yield sharp detail.  Don't forget to use your diffuser, or bounce the flash when possible.  I could have done that with these two photos (bottom) to cut down on highlights and even out the light.


That's all I have for now... See you next time.


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