Product Description

The smc PENTAX-DA 16-50mm f/2.8 ED AL[IF]SDM wide angle zoom lens delivers the highest level of optical quality and includes SDM technology for fast, accurate, quiet focus. Bringing together advanced optical technologies, including aspherical elements, special optical-glass elements and original lens coatings, these new interchangeable lenses are superior to any existing lens series in terms of contrast, clarity and edge-to-edge sharpness.

Product Details

• Brand: Pentax
• Model: B000NO5QVG
• Released on: 2007-08-15
• Dimensions: 3.00" h x 3.00" w x 5.40" l, 1.51 pounds

Features

• 50-135mm telephoto zoom lens with F/2.8 maximum aperture for Pentax digital SLR cameras
• Aspherical elements, special optical-glass elements, and original glass coatings
• Tightly sealed weather- and dust-resistant housing stands up to rainy or dusty conditions
• SDM system produces smooth, quiet autofocusing; SP coating protects exposed lens elements
• Measures 3 inches in diameter and 5.4 inches long; weighs 24.2 ounces without hood

Amazon.com Product Description
Designed for exclusive use with Pentax digital SLR cameras, the Pentax DA series 50-135mm telephoto zoom lens makes it easy to capture close-in sports shots or intimate wildlife photography. The lens is distinguished by its aspherical elements, special optical-glass elements, and original glass coatings, which help produce a high contrast, unmatched clarity, and edge-to-edge sharpness. The lens also boasts a tightly sealed weather- and dust-resistant housing that stands up to rainy or dusty conditions. And users will love the new SDM system, which produces smoother, quieter autofocusing using a built-in supersonic motor. Other details include a Pentax-original Quick-Shift Focus System that switches instantly to manual-focus operation, a Pentax SP coating that protects the exposed lens elements, and a focal length equivalent to 76.5-207mm in the 35mm format.

• Lens mount: Pentax KAF2
• Lens construction: 18 elements in 14 groups
• Angle of view: 31.5 to 11.9 degrees (when used with Pentax digital SLR camera body)
• Aperture control: Automatic
• Minimum aperture: F22
• Metering system: TTL open-aperture metering
• Minimum focusing distance: 1 meter
• Filter size: 67mm
• Maximum magnification: 0.17x
• Dimensions: 3 inches in diameter and 5.4 inches long
• Weight: 24.2 ounces (without hood)

Customer Reviews

One of the best Pentax lenses ever!
After anxiously awaiting the new DA* series of lenses, I bought it the day it was released. I had to photograph the Ujena Bikini Jam in Puerto Vallarta, Mexico and KNEW that I needed the benefits of a tightly sealed, weather proof lens because of the intense humidity. When I first mounted the lens to the body of my K10D (after updating the firmware of course) I was surprised at how incredibly quiet the motor is. I've never had this experience with any lens I've owned. I'm so used to the slight "whir" sound that lenses produced, it was hard for me at first to tell if it was working! The lens focuses quickly and accurately. The lens is nicely finished with nice rubber ribbing on the barrel. It accepts 67mm thread size filters. There may be a temptation to get a standard type Skylight filter. Spend the extra money for the Super Multicoated type. After all, if you spend nearly $1,000 for a lens, why would you skimp on a lower priced filter? The manual focusing mechanism turns freely after you reach the end of the focal length on either side. This is done so that you do not damage the focusing mechanism. For manual focus option, instead of setting your camera body to manual focus, the lens has a switch that allows you to switch between manual focus and auto focus without having to have your body set on manual focus. This is convenient. If the lens is hunting you can easily click over the switch with your thumb without having to remove the camera from your eye. There is no longer an aperture ring on the new digital series lenses. This is logical since all the f-stop settings are now done on the camera body. The stunning sharpness and contrast of this lens is amazing. Distortion is practically non existant and flare is tightly controlled. Make sure you have the lens hood attached to help make sure flare is not an issue. This lens makes the lower priced lenses seem inferior by comparison. This lens is made for professionals and it shows. If you are currently looking for a professional quality Pentax zoom lens, and need the high speed of a 2.8 lens for portrait or glamour photography, this is the one to get. This is an outstanding lens from Pentax. Rush out and get it!

Serious Autofocus Problems
First the good: This is an impressive lens in both feel and looks. There's no mistaking that this is professional glass. For portraits and non-flash situations like stage performances, I wanted a lens that was top-notch in sharpness and overall image quality. According to the specs and the various reviews, this lens delivers...and that's why I bought it. Now the bad: I got a bad copy. When you point your camera at the intended subject and press the shutter, you expect the autofocus system to nail the focus, at least the vast majority of the time, especially with an expensive lens like this. Even a basic point-and-shoot is pretty reliable in that regard. However, not so with the DA* 50-135 copy I received. The majority of my shots are slightly off-focus, enough to not only cancel out the superior sharpness qualities of this lens, but to also ruin what would othewise be an excellent shot. This problem occurs in all types of shooting situations and camera/lens settings. What is more disappointing than having my one faulty lens is finding out that there are others who are experiencing similar problems with their DA* lenses. What I do know is that when I use any other Pentax or Tamron lenses on my K10, everything works fine (yes, I've upgraded the firmware to enable the SDM). In the few times that the focus is spot-on, I can say that the resulting image is quite impressive indeed.

For this amount of money, my tolerance to getting a bad sample is a bit less than if this had been a consumer-grade lens at half the price. I really, really want this lens to work for me the way it's supossed to because I'm a big Pentax advocate and like their recent products and direction in the D-SLR market. So I'm returing mine for another and keeping my fingers crossed. I'll update this review once I get the new copy and can then hopefully report on the superior performance capabilities of the lens.

Update (2/13/08): I was told by Amazon that they couldn't send me a replacement because of a supplier problem, so I'll be getting a refund. After further research into the professional Pentax DA* lens series and seeing a pattern of issues, it's probably best to skip it for now. I'm putting my money on the new Tamron 70-200 f2.8 due out in March. There aren't too many high-end lens options for Pentax D-SLR owners, so there's a lot of anxious folks out there waiting for the first reviews of the new Tamron to come through with hopes that it will deliver the same high level of image quality as a properly working DA* 50-135.

Update (3/2/08): So I find out from Tamron that they don't know when the 70-200 f2.8 lens will be released for the Pentax mount - possibly summer. Since I can't wait that long due to upcoming shooting events, I decided to take another chance with the DA* 50-135 from my local Calumet store. I was able to first test the lens for both focus and centering accuracy. It seemed to work fine - sold! After a number of test shots over the following days, I quickly was able to see that this is indeed a "Five Star" professonal lens. I had recently picked up the Tamron 28-75 f2.8, which is exceptionally sharp for a consumer lens, and did a number of comparison shots with the DA* 50-135. What I found was that the Pentax lens was unquestionably sharper across all apertures, but the weakest at f2.8 (although not that bad at all) with some sharpness falloff at the boarders. The SDM feature is certainly far quieter than the camera's screw-drive motor and very pleasing to have, but I'm not convinced it's any quicker. Image quality from what I've seen so far is excellent. Although the lens body is constructed of plastic, it looks and feels solid and of exceptional quality; a real joy to handle. Now if I could update my rating of this lens, I'd change it to four stars but not five - only because of the number of bad copies released. For a high-end lens, quality control should be better. So far, I'm very pleased with the performance of this professional lens.

Update (3/9/08): Well, after a week of continued testing of this lens, what I've discovered is that this lens, too, now has a focus "problem." While subjects seemed to be sharp most of the time initially, I found that more and more shots were slightly off more often. I then did a number of Point of Focus / Depth of Field tests by shooting a finely marked yardstick from above at about a 45 degree angle about five feet away. With the camera on center spot AF, I selected a point on the ruler and took a number of shots at various apertures and focal lengths. What should occur is that if your Depth of Field is say four inches in length(the area that's sharply focused), your Point of Focus should be about in the middle or just forward of that point. What I found with my second copy of the DA* 50-135 is that the Depth of Focus starts just about at the Point of Focus and goes back. With open aperture shots from f2.8 to f3.2, it's not uncommom for the DoF to occasionally start just after the PoF - and you end up with a slightly fuzzy shot. While the new K20D is supposed to allow for custom adjustment of the DoF and PoF alignment on a lens-to-lens basis (cool!), I'm not keen on keeping a sub-standard copy so that I can fix it by purchasing the new K20D. It's a boarderline issue here - the lens works most of the time, and when it does it's quite impressive. So this lens may also get returned for another, or I'll keep it and eventually have it adjusted by Pentax or "fixed" via the K20D...eventually. I guess Dirty Harry's famous quote applies to those considering the purchase of this lens: "...You gotta ask yourself a question; 'Do I feel lucky?'" My review is back down to two stars.

Update (8/16/08): I upgraded from the K10D to the K20D. The K20D's ability to adjust the auto focus system for individual lenses made it possible to finally see how good the Pentax 50-135 really is, since I had a preexisting focus issue with my copy of this lens. I don't believe there is another lens for the Pentax mount that delivers this high a degree of overall sharpness, contrast and saturation. With a K20D's auto focus adjustment cranked up to max -10 to compensate for the lens calibration issue, focus with this lens is now more accurate than any other lens I own. Just don't expect great performance for action shots (that's the Pentax auto focus system not the lens). Where this lens is a real jewel is at music concerts or stage performances with stage lighting. F2.8 at any focal length is still sharp in the center but f3.5 - f4.0 and higher is excellent overall. I've found that the K20D is the desired camera with this lens since this type of shooting may require wide open aperture and up to 2000 ISO (the K10D cannot match the K20D in lower high ISO noise and greater resolution - when NR is on). However, this would still be one of the best lenses you could use on your K10. Like other reviews on the 50-135 lens, a little more reach would be nice ...but then there's the Pentax f2.8 200mm prime. Finally, it's nice to be using a five star lens!

Update (11/21/09): This may be one of the best Pentax lenses made. It's a pro-level lens without a doubt - pictures taken with it just have that special look of sharpness, contrast, color. I updated the rating to four stars and not five only because of my problems with the SDM focus system starting to slow down over time and not even work on occasion when first mounting the lens until "priming" the focus mechanism by spinning it by hand. Since my K20 has become my backup camera to the Canon 7D (sorry, returned two K-7's), I may install a Katzeye focus screen on the K20 so that the 50-135 can be effectively manually focused should the SDM continue to slow or fail altogether (a firmware option to switch from SDM to the in-body screw drive would be wonderful!).

Superb zoom for the K20D
This is the 2nd sample of the lens, the first was decentered and could not get a sharp photo out if it despite adjusting the AF many times. Amazon sent a replacement before I even got a chance to ship the bad one back, so I had a few days to play with both to make sure the first was actually bad and it was. The 2nd copy was Far sharper and AF'ed correctly with only a minor -3 adjustment. My belief about the 1st bad copy maybe handling as the hood and lens cap was lose inside the box/bag while the lens and box was new and there was no visible damage on the outside or I would not have opened it. Props to Amazon for rather quick turn around with the replacement and no hassles. I am mentioning this as I think Pentax needs to rethink the packaging, while it seems good it might not be enough to protect against typical mail room gorillas and if the hood and lens cap popped off the lens with out damaging the box who knows how they were handling it.

Now more on the 2nd copy, the lens is well built but I find the hood's inner part that attaches to the lens a bit thin, prone to cracking but it will not affect attaching to the lens or actual performance but it is an obvious weak point when compared to the rest of the lens but no worse than most other lens hoods. The lens is made of composites but feels good, not cheap plastics and the build is tight. The weight is obviously all the glass elements inside and this lens has more heft that it would seem for it's size, you would be advised to have a grip on your K20D/K10D to balance the weight. The weight is just right with the grip to also balance on a tripod, the center of gravity will be right before the lens mount and makes perfect balance hand held as well.

Optically I was a bit worried at fist due to the first copy being bad and I gave the 2nd copy a real workout. On test targets it was obvious the lens is very sharp, a tad sharper than my 70mm limited with the exception of 135mm F2.8, it's ok in the center but soft corners that sharpen up at F4, at F5.6 to F11 this lens really shines at all focal lengths. I have not noticed too much bad Ca's or any purpling with my 2nd copy either.

AF speed tho could be better, it's not the typical Pentax slow af syndrome but the lens has a very very long travel from mix to infinity to focus, point to point focusing is decent but slower than the 40mm limited or the 70 ( which happen to be among the fastest focusing lenses on any Pentax ). The Af will track an aircraft in flight well enough and thats good enough for me. In low light it does hunt less than I would expect and the accuracy ( on the 2nd copy ) is perfect and consistent. Sdm is quiet and works as advertised, the focus ring does not turn with af and will turn both past min and max, the friction in the ring does make it good to manually focus but so far the af is more accurate than me trying to focus manually and I am normally good manually focusing.

One word of warning, this lens needs to be shot with a shutter above 1/200 sec, even with the SR on ( and it does work ) hand held. You can see the difference very obviously as the lens is sharp enough to spot the difference. The resolving power is greater than my eyes can do as it picks up the texture on white paper and fine details in text I would only see with a macro lens, these details are lost ( tho the shot is sharp! ) when shooting under 1/125 even with flash and sr if hand held. This is my reasoning at least and this is not a macro lens, we're talking regular focus distances here.

One thing I have noticed on both copies is that focusing between 1 and 1.25m the bokeh is, well just strange, not bad but not great either, beyond 1.5m it's butter smooth right to infinity.

This lens is overall one of the best zooms I have used on any system, it is a little soft 135mm wide open and the plastic hood is a bit cheap but the rest ( of the 2nd copy ) is up to par with it's price. This lens is also related to the tokina 50-135 but while they may get a tripod mount, we get sdm ( usm, hsm sw or what ever, all the same ) and weather sealing, that if it is as good as the K20d's well done weather sealing makes this a very good outdoor/unfavorable weather shooting package. Tho I would be just a little concerned with the lens in drop/kick/knock situations but most zooms are prone to misalignment in that situation, here is where a prime would be better. I will get a chance to have this lens tested against a canon 70-200L soon but I think the Pentax will hold it's ground against it, The Nikon 70-200 F2.8 vr is as sharp to 135mm but that lens is 2x the price of the 50-135 and not sealed! So there is my diatribe about the Pentax 50-135mm F2.8, I will add more as I get to play with this lens more.