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Pentax 55-300mm WR
© KenRockwell.com. All rights reserved.

Intro   Specs   Performance   Recommendations

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Pentax 55-300mm DA

SMC Pentax 55-300mm f/4-5.8 GD DA ED WR (35mm and APC-S coverage, 58mm filters, 16.4 oz./466g, 4.6'/1.4m close focus, about $340). enlarge. I got mine at B&H; I'd also get it at Adorama or at Amazon.

This ad-free website's biggest source of support is when you use those or any of these links to approved sources when you get anything, regardless of the country in which you live. Pentax does not seal its boxes, so never buy at retail or any other source not on my personally approved list since you'll have no way of knowing if you're missing accessories, getting a defective, dropped, damaged, returned, store demo or used lens. My approved sources ship from remote automated warehouses where no salespeople or lookie-loos can ever get their greasy fingers on your new lens before you do. Buy only from the approved sources I use myself for the best prices, service, return policies and selection. Thanks for helping me help you! Ken.


July 2015   Pentax reviews   all reviews


Introduction       top

Intro   Specs   Performance   Recommendations

Adorama pays top dollar for your used gear.

B&H Photo - Video - Pro Audio

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.


Specifications        top

Intro   Specs   Performance   Recommendations



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.


Optics       top

12 elements in 8 groups.

Partly multicoated, oddly not branded as "Super Multi Coating" (SMC).


Diaphragm       top

Pentax 55-300mm DA

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

1:3.6 (0.28x).


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




Hood       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.


Caps       top

Nice 58mm O-LC58 front cap.

The usual Pentax bayonet rear cap.


Case      top

Pentax S80-160 case

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.


Size       top

Pentax specifies 2.8" (71mm) diameter by 4.4" (111.5mm) long.


Weight       top

16.440 oz. (466.0 g) actual measured weight.

Pentax specifies 16.4 oz. (440 g).


Included       top



S80-160 case.

PH-RBI 58mm hood.


Pentax Model Number       top



Price, USA        top

2015 July: $340.


Performance         top

Intro   Specs   Performance   Recommendations

Overall    Autofocus    Bokeh   Breathing

Distortion   Ergonomics   Filters

Lateral Color Fringes   Macro   Mechanics

Sharpness      Spherochromatism


Overall     performance      top

Pentax 55-300mm DA

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     performance      top

Autofocus is via 1980s technology: a motor in the body connected via a screw coupling.


AF Speed

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.


Auto/Manual Switching

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

Manual focus is easy; just turn the ring.


Bokeh     performance      top

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.

Pentax 55-300mm DA Bokeh

Pentax 55-300 DA shot at 55mm at f/4 on a Pentax K3 II. Camera-original © JPG file.


Pentax 55-300mm DA Bokeh

Pentax 55-300 DA shot at 55mm at f/4 on a Pentax K3 II. Camera-original © JPG file.


Focus Breathing     performance      top

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.


Distortion     performance      top

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.

On APS-C at 10' (3m)

Correction factor with uncorrected images


© 2015 KenRockwell.com. All rights reserved.


Ergonomics     performance      top

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.


Filters, Use with     performance      top

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.


Lateral Color Fringes     performance      top

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.


Macro     performance      top

It gets very close since it can focus to 4.6'/1.4m at 300mm:

Pentax 55-300mm WR Macro performance

Rolex Submariner at close-focus distance at 300mm shot on Pentax K3 II at f/20. Camera-original © JPG file.


Pentax 55-300mm WR Macro performance

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.


Mechanics     performance      top

Pentax 55-300mm DA

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.


Filter Threads



Hood Mount



Front Barrel



Focus Ring

Metal with rubber grip.



Printed on red-anodized aluminum ring on the zoom ring.


Zoom Ring

Plastic, rubber-covered


Rear barrel




Looks like all plastic.


Moisture seal at mount




Chromed metal.





Serial Number

Printed on a sticker glued into a recess in the bottom of the black plastic lens barrel.


Date Code

None found.


Noises When Shaken

Mild clunking.


Made in



Sharpness     performance      top

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     performance      top

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.


Recommendations         top

Intro   Specs   Performance   Recommendations

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.

If you find my work here helpful, my biggest source of support for this free website is if you get yours at B&H, at Adorama or at Amazon. When you use those or any of these links to approved sources when you get anything, regardless of the country in which you live, it helps me keep adding to this free website — but I receive nothing for these efforts if you take the chance of buying elsewhere. Unlike a bottle of milk or a CD, DVD or Blu-Ray disc, Pentax doesn't seal its boxes so you have no idea if you're actually getting a used product if you risk buying at retail. Never buy at retail.


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Mr. & Mrs. Ken Rockwell, Ryan and Katie.


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06 July 2015