Lens Spotlight: M50M - Jason Doss

Lens Spotlight

smc Pentax-M 50mm f/4 Macro

& Converter-A 1.4x-S

The progression through the lens collection continues.  Each lens contains a unique optical formula and physical construction that affects the handling and output in an individual way.  Therefore, the addition of a teleconverter will produce a new optical formula, and this is the basis for treating lens/TC combos as individual lenses.

The addition of a teleconverter to a macro lens will increase the magnification proportional to the power of the TC, but it will not affect close-focusing distance.  Essentially, the TC acts as an enlarger behind the lens.  Close up lenses do the opposite; they are mounted on the front of the lens and provide magnification by reducing close-focus distance.  So, if you are trying to get high magnification photographs of a hornet's nest, you might consider using a teleconverter on your macro lens instead of a close-up lens.

The lens is 160g (0.35#) and, focused at infinity, 43mm long (1.7 inches), and with the teleconverter attached, the combination weighs 305g (0.67#) and 65mm (2.5 inches). The lens has 5 aperture blades and 49mm filter threads. The aperture of f/4.0 is slow for lenses of this focal length, and the addition of the TC adds another stop, so the actual fastest aperture is f/5.6. The lens bears the usual aperture ring and has a rubberized grip for easy manual focusing. Minimum focus distance is 23cm (9 inches) producing 1:2.8 reproduction ratio (0.7x). 

The common wisdom is that teleconverters will decrease image quality proportional to the degree of magnification offered by the TC. In fact, this is often extended to say that any added glass, including filters, must necessarily degrade image quality to some extent.  The logic is sound, as the more fiddling with the light one does by sending it thru glass elements, the lower quality result one might achieve.

Although one does not expect a teleconverter to improve base features of the lens (sharpness, contrast, etc), it is not necessarily true that their addition will degrade performance. Such is the case with this combination. I find sharpness and image quality with the TC attached to be indistinguishable with the "bare lens."  Check out these images.

Over the past few weeks, my lovely wife and I have been working hard to remove brush and dead trees from the landscape behind our house.  I always take my camera with me everywhere, even into the woods while carrying a chainsaw in the other hand, and this day was no exception.  All three of these images are among the fruits of that labor.

Top frame, we see some kind of lichen with "golf tees" sticking out of them.  After I took a breather and plopped down on the leafed forest floor, I started rooting around in the leaf litter like I often do because I'm actually only 6 years old.  This time, we found wide patches of this lichen with "golf tees" sticking out of them, and I took several shots. 

Middle frame shows a glorious patch of turkey tail fungus growing on a moss covered log.  We were moving logs all day (well, for a couple hours at least), but I refused to touch this one because it was just so fantastic! 

Finally, bottom frame shows one of the few trees with leaves still on at the time, and berries too.  This is a dogwood which is among our favorite trees.  We removed some fast growing gum trees, a few gnarly cedars that were in the way, but we did our best to leave all the oaks and damaged zero dogwoods during our brush removing rampage.

Again, click any photo to see larger versions, and comments can be left on this page or under each photo if you are so inclined.

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

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