Lens Spotlight: K15 - Jason Doss

Lens Spotlight

smc Pentax-K 15mm f/3.5

An ultrawide lens like this back in the 1970s used to be hard to make, large, heavy, and super expensive.  Things have changed in 50 years (WTF... 50 years?!) and largely for the better.  Nevertheless, when this baby came to my attention, and more importantly an excellent quality one came up on Japanese eBay, I went for it.

The lens is large. Compared to the current Pentax 15mm lens (the DA version), this one is three times heavier and twice as long.  Not only that, but just look at its eye!  That huge 80mm wide bulbous (and in my case, dusty... I'll do better next time) front element captures a 100 degree horizontal (111' diag) field of view.  That's as wide as you could get in 1975.

This lens is the same as the previous Takumar version for the Spotmatic, and the subsequent A version with automatic aperture control, but for some reason the ratings at Pentax Forums are wild and all over the place.  The K version (the subject here) garners only 7.67 from 12 reviews, but the A version gets 9.33 of 8 reviews, and the earlier Takumar gets an amazing 9.75 out of 8 reviews.  I haven't done an in-depth analysis on what these people are saying, however it is a fact that there is no difference at all in the optical formula.

The lens is 600 g (1.3#) and, focused at infinity, 82mm long (3.2 inches) and has 6 aperture blades and no filter threads. The aperture of f/3.5 but this can't really be compared to other lenses due to the uniqueness of this focal length. The lens bears the usual aperture ring, a built-in and permanently fixed lens hood, and has a rubberized grip for easy manual focusing. This lens has four built-in filters, including Yellow Y48(Y2), Skylight, L39(UV),  and Orange O56(O2). Minimum focus distance is 30cm (11 inches) producing 1:12.5 reproduction ratio (0.08x).

So, as usual, here are three examples from this thing. The subject was outdoor photography at the Steel Creek area at the Buffalo National River. It's one of my favorite places on the planet, as is all of fabulous Newton County, and a place we visit often. 

This fall, the weather rained all over the peak colors. The trees were green but starting to turn, then 10 days of drizzle, rain, and overcast skies, and then the trees were mostly brown or naked. The good news is that some of the trees here kept some color on, probably just for me to show up and get their photo.  This photo was taken very close to the tree on the left of this frame... surprisingly close, even though it looks like it's 100 feet away. I was in the tall grass by at least a couple of steps. The built-in skylight filter was in, which might (?) explain the darkening of the sky on the left side, or maybe that's just a natural effect this time of year.

The second photo was taken from directly under the red oak tree, lens pointed more or less straight up into the leaves. I was hoping for a perspective type shot which didn't work since the leaves were too far from the lens. Nevertheless, this shot is presented to show the lens flare at the 7 o'clock position. Considered a defect by some, a feature by others like myself, the multi-colored hexagons give away the lens's 6 aperture blades, and are due to sunlight hitting the edge of the front glass and bouncing around inside the lens. They are essentially internal reflections. The effect can be prevented with a strategically placed hand when necessary.

Wide angle lenses are often very good close-up lenses, so long as you don't mind getting a lot of your background in your shot. Remember, previous write-ups on this very blog explained to some degree how longer focal lengths reduce background compared to shorter focal lengths when the main subject is kept the same size in the frame. Perhaps some day, I'll dedicate an article to this subject since I've mentioned it now twice. At any rate, in attempts to show off some close focus action, here is an attempt to frame a cluster of mushrooms on a moss and fern-covered log on a visit to the Lost Valley Trail. The lens is racked out to minimum focus distance, and you can see we're only about two leaf-lengths away from the mushrooms.  This shot would have been much more effective with a 28mm lens, or if the subject were much larger.

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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