Lens Spotlight: M120 - Jason Doss

Lens Spotlight

smc Pentax-M 120mm f/2.8

No one really needs a 120mm lens.  The range is adequately covered by 100mm and 135mm primes such that a half step forward or back, respectively, would be sufficient to duplicate the focal length when "zooming with the feet."  I'm a prime lens afficianado and so zooming with my feet is what I do to achieve acceptable framing if the lens of the day isn't quite the right choice.  I've never been in a situation where I couldn't adjust with either 100mm or 135mm to such an extent that 120mm would have been "required."


However, 120mm is a unique focal length, and therefore the collector bug in my mandated its acquisition.  The lens is very similar, but slightly larger than the M100f2.8 lens previously discussed.  The main difference, and in my opinion the difference that makes the 120mm the better lens, is the built-in lens hood.  These M-series lenses are so small already, yet they manage to cram in lens hoods into many that need them.


The lens is 270g (0.6#) and, focused at infinity, 63mm long (2.5 inches) and has 8 aperture blades and 49mm filter threads. The fast aperture of f/2.8 is about average for lenses of this focal length. The lens bears the usual aperture ring and has a rubberized grip for easy manual focusing. Minimum focus distance is 120cm (3.9 ft) producing 1:7.7 reproduction ratio (0.13x).

The image quality of this lens I think is as good as the M100f2.8 or maybe even better.  The slightly larger size is noticable and makes handling just a wee-bit easier, and again the lens hood is really useful.  I know the built-in hoods are sometimes are not as efficient as a separate hood, having one built into the lens that requires zero fiddling and that cannot get lost is a very welcome addition.  Wider lenses would not necessarily benefit since they would need to 'fan out' from the edge of wide lenses, which might explain why they don't exist.  I do, however, think normal and short telephoto lenses could have benefited from short built-in hoods.  I know... I shall go back in time and complain to the manufacturers at once.


Here I have to show three shots taken recently with this lens.  Top is a shot of the Jasper Farmer's Market as it wraps up.  Usually, there are vendors spread around the block but it's late in the season and late in the day, so only a few remain.  The trees in front of the courthouse have changed color in spectacular style, unlike most trees in the area at the time this photo was shot.  Click the photo to see larger and full size versions.


Center is a close-up shot of turning leaves on a young sweet gum tree near my house.  I could have used a wider aperture for shallower DOF to isolate the largest leaf in the 10:00 position.  I've been doing this for years, more than a decade now, and still I find in retrospect changes I should have made before the shot.  Learning goes on a lot longer than we have time to learn, unfortunately.


Finally, we have the grand view of Round Mountain at sunset.  This day had a cloudless sky, which is good and bad.  Most cloudy skies are overcast but sometimes the clouds are scattered or breaking up which can provide quite a light show this time of day.  The colors have not reached peak here at this time, and it appears the trees are changing in such an asynchronous way that we'll only end up with spots of color on a mainly gray landscape.  


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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