Pentax 55-300mm WR
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This SMC Pentax 55-300mm DA is a relatively inexpensive telephoto zoom for Pentax digital SLRs.
It's better than I expected for a mostly plastic lens. It's reasonably sturdy and performs well. It focuses closer than most professional zooms: 4.6 feet or 1.4 meters, which gives great close-ups.
Most Pentax digital bodies provide image stabilization with this unstabilzed lens.
You can grab the focus ring at any time the AF system isn't actually trying to move the lens for instant manual override.
Formats & Compatibility
This 55-300 lens is optimized for APS-C cameras. It has the KAF2 lens mount.
It's not supposed to work on full-frame—but I tried it, and it usually covers most of the 35mm frame. I wouldn't call this a full frame lens by any means, but if you do use it, the corners may get fuzzier, but at least they don't cut off to black. Of course it's fine on digital SLRs.
It mounts, meters, manually focuses and shoots on Pentax's classic 35mm cameras, but since it has no aperture ring, it always meters and shoots at f/22 at 55mm to f/32 at 300mm. Viewing and focussing is wide open, but you have to imagine that it's always going to shoot at f/22 ~ f/32.
Pentax calls this the HD PENTAX-DA f/4-5.8 55-300mm ED WR.
HD refers to new coating that replaces the classic SMC multicoating.
DA means it works on Pentax digital cameras.
ED means it uses extra-low dispersion glass to give sharper pictures, specifically to reduce secondary chromatic aberration.
WR means weather resistant, owing to a few gaskets inside to try to give it some resistance to dust and water.
12 elements in 8 groups.
Partly multicoated, oddly not branded as "Super Multi Coating" (SMC).
Pentax EF 55-300mm DA at f/22.
6 rounded blades.
Stops down to f/22~32.
Maximum Aperture top
f/4 at 55mm.
f/5.8 at 300mm. That's f/5.8, not f/5.6, not that there's any significant difference.
Focal Length top
On Pentax digital cameras it will see angles-of-view similar to what an 85-450mm lens would see on a 35mm camera.
Angle of View
29º ~ 5.4º diagonal on Pentax digital.
Close Focus top
4.6 feet (1.4m) from the image plane.
Maximum Reproduction Ratio top
Hard Infinity Focus Stop? top
You have to let the AF system focus for you at infinity.
Focus Scale top
Depth-of-Field Scale top
Infra-Red Focus Index top
Filter Thread top
The plastic bayonet hood is included.
It has a clever little sliding cover that lets you rotate a grad or polarizer without removing the hood.
Nice 58mm O-LC58 front cap.
The usual Pentax bayonet rear cap.
S80-160 case, Pentax 55-300mm WR.
The case is a padded nylon pouch, which is perfect for throwing in a backpack, trunk or glove box.
Pentax specifies 2.8" (71mm) diameter by 4.4" (111.5mm) long.
16.440 oz. (466.0 g) actual measured weight.
Pentax specifies 16.4 oz. (440 g).
PH-RBI 58mm hood.
Pentax Model Number top
Price, USA top
2015 July: $340.
SMC Pentax 55-300mm DA.
The Pentax 55-300mm DA is pretty nice lens for its low price. It handles well, has little distortion and focusses very close.
Autofocus is via 1980s technology: a motor in the body connected via a screw coupling.
AF is relatively noisy and slow, as if we're still in the 1980s.
It's fast enough for most uses, but it won't be if you have to focus all the way from near to far quickly. So long as you're in a similar range, like shooting your kids in sports, it will work quickly, but expect it to take one second to rack all the way in or out from one end to the other.
Just grab the ring at any time the camera isn't trying to autofocus.
The ring turns during autofocus; keep your fingers away until it stops.
Manual focus is easy; just turn the ring.
Bokeh, the quality of out-of-focus areas as opposed to the degree of defocus, is fair to good at 55mm, and very good to excellent at 300mm.
Focus breathing (the image changing size as focused) is mostly of interest to cinematographers who don't want the image changing size ("breathing") as the lens is focused among different subjects.
The image from the Pentax 55-300mm DA gets larger as focused more closely.
The Pentax 55-300mm DA has less distortion than expected for a 6:1 zoom, and many Pentax cameras can be set to correct for this as well.
Shot uncorrected, use these correction factors in Photoshop's lens distortion filter to correct it fully.
These aren't facts or specifications, they are the results of my research that requires hours of photography and calculations on the resulting data.
© 2015 KenRockwell.com. All rights reserved.
This little lens handles much better than expected. It's sturdy and the grippy rings are just that: sturdy and grippy.
Keep your hands off the focus ring anytime the AF system is turning it, otherwise, grab it at any other time for instant manual focus override.
The plastic 58mm filter threads are big enough that at least a couple of stacked filters won't cause any vignetting on digital.
There is no need for expensive "thin" filters.
There aren't the usual lateral color fringes on a Pentax K3 II at 24MP, but there are many other various chromatic aberrations visible at larger apertures.
You'll see all sorts of minor color fringes wide-open, but they go away as stopped down.
It gets very close since it can focus to 4.6'/1.4m at 300mm:
Crop from above image at 100%. If this is 6" (15cm) wide on your screen, the full image would print at 40 x 60" (1 x 1.5 meters)! Camera-original © JPG file.
Pentax EF 55-300mm DA. bigger.
The Pentax 55-300mm is better made than most plastic lenses. It has a metal mount and focus ring, and the waffle-pattern grips are nicer than most others today. It's certainly nicer than Nikon or Canon's all-plastic 55-300mm lenses.
Metal with rubber grip.
Printed on red-anodized aluminum ring on the zoom ring.
Looks like all plastic.
Moisture seal at mount
Printed on a sticker glued into a recess in the bottom of the black plastic lens barrel.
Noises When Shaken
Image sharpness depends more on you than your lens, and lens sharpness doesn't mean much to good photographers. It's the least skilled hobbyists who waste the most time blaming fuzzy pictures on their lenses, while real shooters know that few photos ever use all the sharpness of which their lenses are capable due to subject motion and the fact that real subjects are rarely perfectly flat.
The Pentax 55-300 is sharp in the center wide-open, and gets even better as stopped down.
It can be softer on the sides wide-open, also improving quickly as stopped down. That's not usually important, as there is rarely anything in focus on the sides, and even if there was, few people print 6 feet (2 meters) wide where it might matter.
Like all lenses it gets softer at the very smallest apertures due to diffraction.
Spherochromatism, misnamed "color bokeh" by laymen, is when out-of-focus highlights take on color fringes at full aperture.
Spherochromatism is a completely different aberration from lateral color fringes.
It has a little bit of spherochromatism at the 300mm end, where background highlights can have slight yellow fringes and foreground highlights can have slight blue fringes wide-open.
This is a great little telephoto lens for Pentax digital cameras. It's small, light, sturdy, inexpensive and focuses close enough to eliminate the need for a dedicated macro lens for most uses.
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06 July 2015