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Technical Details
- Brand Name: Pentax
- Model: B000NO5QVG
- Lens Type: zoom
- Minimum focal length: 50 millimeters
- Maximum focal length: 135 millimeters
Product Details
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Product Description
Amazon.com
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)
Product Description
Pentax SMC DA* Series 50-135mm f/2.8 ED IF SDM Telephoto Zoom Lens for Pentax and Digital SLR Cameras
Available Warranties for This Item
Customer Reviews
Most Helpful Customer Reviews
61 of 61 people found the following review helpful
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!
98 of 104 people found the following review helpful
By P. VANDALEN
Amazon Verified Purchase
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!).
Update (2/7/10): The SDM is now dead. I'm not sending it in for repairs as I believe there is an inherrant problem with the SDM design/build so that a fix may also not last that long. I've been reading about others with similar problems with their SDM. Since I've been so impressed with the Canon 7D and the L lenses used with it, the failure of my previously favorite lens (50-135) has not been an issue, until I remind myself that the K20 is still my backup camera.
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!).
Update (2/7/10): The SDM is now dead. I'm not sending it in for repairs as I believe there is an inherrant problem with the SDM design/build so that a fix may also not last that long. I've been reading about others with similar problems with their SDM. Since I've been so impressed with the Canon 7D and the L lenses used with it, the failure of my previously favorite lens (50-135) has not been an issue, until I remind myself that the K20 is still my backup camera.
39 of 41 people found the following review helpful
Amazon Verified Purchase
When I first got this lens, my initial thoughts were "wow, this thing is gorgeous". I love the gold highlights, the green line near the mount, and the massive zoom and focus rings. The large front element makes this lens look like it means business. This thing looks fantastic.
On my K-7, this lens is perfectly balanced. The large zoom ring means the lens has a wide range of space to support it, so I suspect it would be well balanced on just about any Pentax camera. That zoom ring feels smooth, with a good amount of resistance.
The focus ring is very similar, it's even larger than the zoom ring. It also has a fairly smooth motion with good resistance, although I found it felt kinda "dry" initially. Nowhere near the smoothness of my Super Takumar 50mm F1.4's focus ring, which is buttery smooth. It also has a super-long 130 degree sweep, which would be great for manual focusing but is far too long for an auto-focus lens. One oddity I hadn't experienced with a lens before: when I reach the end of the focus throw, the focus ring doesn't stop turning. There's a distinct "clunk" of the internal focusing mechanism reaching its limit, but the ring can continue to be turned indefinitely. It's a weird feeling, none of my other lenses behave this way.
Its size is a bit daunting at first, but this is mostly due to the fact that it focuses and zooms internally. So no matter what focal length you're using or where you're focusing, this lens always stays exactly the same length. The weight is also a bit much to carry around your neck during a long shooting session. After buying this lens, I got a new neck strap from Op/Tech to help reduce the strain on my neck, and it's been a huge help.
I've been using this lens regularly for over a month now, and I've mostly gotten used to the way it behaves. But one thing that still bugs me is the 3 foot minimum focus distance. The F2.8 aperture and 50mm focal length beg for this lens to be used indoors in low light, but the 3 foot minimum focus distance makes this a really frustrating task. I keep getting caught by this, and have to move back or stand on my tip toes to get 3 feet from my subject. I really wish this thing had a macro mode, or at least allowed closer focusing. 3 feet sucks.
Outdoors, this lens is at its best. Sharpness is impressive at any focal length, including the extremes. Even at F2.8, overall sharpness is surprisingly good. I've never seen a lens that gives such great results wide open. Of course, stopping down to F4 makes things even better.
Contrast and saturation are gorgeous. The colours come out vivid and clear, and chromatic aberration is incredibly well controlled. I have yet to be able to induce flare, even on purpose. The lens hood does a perfect job of keeping stray reflections off the lens. It's even lined with black felt on the inside!
Focusing performance is... disappointing. With all the hype from Pentax over SDM, I expected focusing to be on par with high end Canon and Nikon offerings, but the truth is, it barely matches the kit lens with its screw-drive focusing. Accuracy in daylight is excellent, but it takes a long time to get from close focus to infinity. The focus throw is so long, you can feel the mechanism rolling through its entire range... it reminds me of the distant rumble of a bowling ball rolling down the aisle. Sometimes, there's a hesitation before the focus mechanism gets going. Like it's not sure if I really meant to half-press the shutter button. Occasionally, when I haven't used the lens in a couple days, the focusing mechanism takes a few tries to "wake up". It won't move at all the first few times I half-press the shutter button. Once it does wake up, the precision is excellent. It always focuses accurately on my target. If it doesn't have to go through its entire focus range to find a target, it's usually pretty quick. So if I manually focus real quick and then half-press the shutter button, I can get focus blazingly fast. But this is an annoying two-step process. Overall, I'd say it compares favourably with the kit lens in this respect, but it doesn't come close to the competition. It doesn't even come close to my old and ultra-cheap SMC Pentax F 35-70mm F3.5-4.5, which auto-focuses like greased lightning on ice.
As soon as I get out of daylight, focus performance drops like a rock. This lens has a tendency to hunt more than my kit lens does. It'll often sweep through its entire range twice, and then give up, even when there's an obvious line to focus on RIGHT THERE IN THE MIDDLE!!! Honestly, I don't get it. With an F2.8 aperture, it should have plenty of light to focus easily in most situations, but somehow that doesn't matter. The worst part is, sweeping through its range takes so long, by the time it's failed to focus, my shot is often gone. On the upside, the focusing mechanism is whisper quiet. I hear it when I operate the camera, but anyone around me can't hear it at all.
I've been using this lens on my K-7 in winter, through some horrible snow storms and pouring rain. The combination never missed a beat. I've even half-buried the camera in snow to get different angles of shots. It's great to be able to do these things and not worry about water getting into the camera. Weather sealing is one of this lens' great qualities, and definitely contributes to the rating I gave it.
Since I mainly use this lens outdoors during the day, it's been a perfect fit for me, hence the rating. It's really unfortunate that I can't make better use of it indoors or in low-light, but that's not what I got it for. I mainly got it for outdoor shots of static objects, and for this purpose the lens is excellent. I'm also hoping to use it a lot when the Canadian Football League season starts up again in July, although I'm not sure how it will do with fast-moving subjects. I guess I'll find out the hard way...
===================
*Update* December 8th, 2010
As I feared from the moment I decided to purchase this lens, the auto-focus motor has failed. I really hoped that the rampant stories of failed auto-focus motors with this lens were a thing of the past, and that Pentax had resolved the issue on newer copies, but apparently my hope was misplaced. I have now joined the ranks of idiots who dumped nearly a grand on this lens only to have it fail within one year. I'm lucky that it failed *just* before the warranty expired, but I don't hold much hope that the replacement motor will work any longer than the original did. Considering how widespread this issue is, it's insulting that Pentax would do nothing to resolve it. They market this lens as a professional product, but I feel more like a sap for falling into their trap. Consequently, I'm downgrading my rating from 4 stars to 2. This lens is still optically fantastic, and most of the benefits I listed in initial review are still valid. But the failed auto-focus motor, coupled with the fact that this is a serious, widespread problem, have left me with a bitter taste in my mouth.
I should point out that since I wrote the initial review, I've used this lens regularly on 2 other Pentax bodies. A K-x and a brand new K-5. Auto-focus performance was dramatically improved on the K-5, to the point where I could use this lens indoors in low-light without much trouble... at least until the auto-focus motor failed.
===========================
*Update* March 6th, 2011
After getting this lens fixed under warranty, I hoped everything was well. After all, Pentax's official repair facility put in a BRAND NEW SDM MOTOR and re-assembled the lens to factory specifications. They gave it the green light and sent it back to me in supposedly pristine condition. It took them over a month to do this, so I was without my lens for 5 weeks.
Within a month of receiving the repaired lens, it failed again. The SDM motor failed completely, and the focus mechanism seized in place, so even manual focus didn't work anymore. The focus ring just turns and turns in my hand and accomplishes nothing. I must go through yet another repair through the Pentax repair facility (C.R.I.S. in Arizona).
===========================
*Update* March 30th 2011
That's it, I'm done with this lens. C.R.I.S. had it back to me quickly this time since it was a subsequent failure, and they yet again claim to have fixed it. But the *new* SDM motor they put in has yet again burned out. It was giving some minor shudders during focus, and then I smelled smoke and it no longer worked.
I'm getting it fixed one last time (still under warranty, thankfully, I get a new 6 month warranty on each repair), and then I'm selling it. I'm sick and tired of these repeated failures. No photographer should have to go through this kind of frustration, especially with a product that's labeled as a "Professional Lens" by the manufacturer.
On my K-7, this lens is perfectly balanced. The large zoom ring means the lens has a wide range of space to support it, so I suspect it would be well balanced on just about any Pentax camera. That zoom ring feels smooth, with a good amount of resistance.
The focus ring is very similar, it's even larger than the zoom ring. It also has a fairly smooth motion with good resistance, although I found it felt kinda "dry" initially. Nowhere near the smoothness of my Super Takumar 50mm F1.4's focus ring, which is buttery smooth. It also has a super-long 130 degree sweep, which would be great for manual focusing but is far too long for an auto-focus lens. One oddity I hadn't experienced with a lens before: when I reach the end of the focus throw, the focus ring doesn't stop turning. There's a distinct "clunk" of the internal focusing mechanism reaching its limit, but the ring can continue to be turned indefinitely. It's a weird feeling, none of my other lenses behave this way.
Its size is a bit daunting at first, but this is mostly due to the fact that it focuses and zooms internally. So no matter what focal length you're using or where you're focusing, this lens always stays exactly the same length. The weight is also a bit much to carry around your neck during a long shooting session. After buying this lens, I got a new neck strap from Op/Tech to help reduce the strain on my neck, and it's been a huge help.
I've been using this lens regularly for over a month now, and I've mostly gotten used to the way it behaves. But one thing that still bugs me is the 3 foot minimum focus distance. The F2.8 aperture and 50mm focal length beg for this lens to be used indoors in low light, but the 3 foot minimum focus distance makes this a really frustrating task. I keep getting caught by this, and have to move back or stand on my tip toes to get 3 feet from my subject. I really wish this thing had a macro mode, or at least allowed closer focusing. 3 feet sucks.
Outdoors, this lens is at its best. Sharpness is impressive at any focal length, including the extremes. Even at F2.8, overall sharpness is surprisingly good. I've never seen a lens that gives such great results wide open. Of course, stopping down to F4 makes things even better.
Contrast and saturation are gorgeous. The colours come out vivid and clear, and chromatic aberration is incredibly well controlled. I have yet to be able to induce flare, even on purpose. The lens hood does a perfect job of keeping stray reflections off the lens. It's even lined with black felt on the inside!
Focusing performance is... disappointing. With all the hype from Pentax over SDM, I expected focusing to be on par with high end Canon and Nikon offerings, but the truth is, it barely matches the kit lens with its screw-drive focusing. Accuracy in daylight is excellent, but it takes a long time to get from close focus to infinity. The focus throw is so long, you can feel the mechanism rolling through its entire range... it reminds me of the distant rumble of a bowling ball rolling down the aisle. Sometimes, there's a hesitation before the focus mechanism gets going. Like it's not sure if I really meant to half-press the shutter button. Occasionally, when I haven't used the lens in a couple days, the focusing mechanism takes a few tries to "wake up". It won't move at all the first few times I half-press the shutter button. Once it does wake up, the precision is excellent. It always focuses accurately on my target. If it doesn't have to go through its entire focus range to find a target, it's usually pretty quick. So if I manually focus real quick and then half-press the shutter button, I can get focus blazingly fast. But this is an annoying two-step process. Overall, I'd say it compares favourably with the kit lens in this respect, but it doesn't come close to the competition. It doesn't even come close to my old and ultra-cheap SMC Pentax F 35-70mm F3.5-4.5, which auto-focuses like greased lightning on ice.
As soon as I get out of daylight, focus performance drops like a rock. This lens has a tendency to hunt more than my kit lens does. It'll often sweep through its entire range twice, and then give up, even when there's an obvious line to focus on RIGHT THERE IN THE MIDDLE!!! Honestly, I don't get it. With an F2.8 aperture, it should have plenty of light to focus easily in most situations, but somehow that doesn't matter. The worst part is, sweeping through its range takes so long, by the time it's failed to focus, my shot is often gone. On the upside, the focusing mechanism is whisper quiet. I hear it when I operate the camera, but anyone around me can't hear it at all.
I've been using this lens on my K-7 in winter, through some horrible snow storms and pouring rain. The combination never missed a beat. I've even half-buried the camera in snow to get different angles of shots. It's great to be able to do these things and not worry about water getting into the camera. Weather sealing is one of this lens' great qualities, and definitely contributes to the rating I gave it.
Since I mainly use this lens outdoors during the day, it's been a perfect fit for me, hence the rating. It's really unfortunate that I can't make better use of it indoors or in low-light, but that's not what I got it for. I mainly got it for outdoor shots of static objects, and for this purpose the lens is excellent. I'm also hoping to use it a lot when the Canadian Football League season starts up again in July, although I'm not sure how it will do with fast-moving subjects. I guess I'll find out the hard way...
===================
*Update* December 8th, 2010
As I feared from the moment I decided to purchase this lens, the auto-focus motor has failed. I really hoped that the rampant stories of failed auto-focus motors with this lens were a thing of the past, and that Pentax had resolved the issue on newer copies, but apparently my hope was misplaced. I have now joined the ranks of idiots who dumped nearly a grand on this lens only to have it fail within one year. I'm lucky that it failed *just* before the warranty expired, but I don't hold much hope that the replacement motor will work any longer than the original did. Considering how widespread this issue is, it's insulting that Pentax would do nothing to resolve it. They market this lens as a professional product, but I feel more like a sap for falling into their trap. Consequently, I'm downgrading my rating from 4 stars to 2. This lens is still optically fantastic, and most of the benefits I listed in initial review are still valid. But the failed auto-focus motor, coupled with the fact that this is a serious, widespread problem, have left me with a bitter taste in my mouth.
I should point out that since I wrote the initial review, I've used this lens regularly on 2 other Pentax bodies. A K-x and a brand new K-5. Auto-focus performance was dramatically improved on the K-5, to the point where I could use this lens indoors in low-light without much trouble... at least until the auto-focus motor failed.
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*Update* March 6th, 2011
After getting this lens fixed under warranty, I hoped everything was well. After all, Pentax's official repair facility put in a BRAND NEW SDM MOTOR and re-assembled the lens to factory specifications. They gave it the green light and sent it back to me in supposedly pristine condition. It took them over a month to do this, so I was without my lens for 5 weeks.
Within a month of receiving the repaired lens, it failed again. The SDM motor failed completely, and the focus mechanism seized in place, so even manual focus didn't work anymore. The focus ring just turns and turns in my hand and accomplishes nothing. I must go through yet another repair through the Pentax repair facility (C.R.I.S. in Arizona).
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*Update* March 30th 2011
That's it, I'm done with this lens. C.R.I.S. had it back to me quickly this time since it was a subsequent failure, and they yet again claim to have fixed it. But the *new* SDM motor they put in has yet again burned out. It was giving some minor shudders during focus, and then I smelled smoke and it no longer worked.
I'm getting it fixed one last time (still under warranty, thankfully, I get a new 6 month warranty on each repair), and then I'm selling it. I'm sick and tired of these repeated failures. No photographer should have to go through this kind of frustration, especially with a product that's labeled as a "Professional Lens" by the manufacturer.
Most Recent Customer Reviews
1.0 out of 5 stars
SDM Failure
The SDM (which is the focus mechanism) failed on this lens within a few months of purchase.
The pictures are decent, but I can get better ones with my old Russian manual... Read more
The pictures are decent, but I can get better ones with my old Russian manual... Read more
Published 2 months ago by Hugh Mann
5.0 out of 5 stars
Pentax zoom lens
Excellent quality lens. Tack sharp images. I was going to purchase a 4.0 lens, but glad that I paid a little extra for the 2.8 lens.
Published 3 months ago by David P. Dipaolo MD
5.0 out of 5 stars
Sharp, fast, quiet, accurate!
Highly recommended for weddings, parties, indoor sports. The only drawback is that it is a bit heavy, otherwise go for it.
Published 4 months ago by Eric
4.0 out of 5 stars
Very fine lens; somewhat slow focusing
Little needs be be said about the performance of the Pentax DA* 50-135/2.8. This lens is sharp rought out of the gate at f/2.8. Set your dSLR to A mode at 2.8, and enjoy. Read more
Published 5 months ago by Serac
5.0 out of 5 stars
Works as expected
I was using pentax limit lens (DA 40 and 70mm), which gives great result in small body. Then decided to try star lens; works well, gives good result and provide different view with... Read more
Published 11 months ago by Young Bae Park
2.0 out of 5 stars
If only the auto focus worked
My oldest auto-focus lens is a 300 mm f4.5 EDF lens bought in 1988. I have used it in deserts, rain and over rough terain so it have taken a few knocks and looks like it's been... Read more
Published 12 months ago by Bengo
5.0 out of 5 stars
Perfect lens to carry with
It is the second copy of my purchase. The first copy has problem on focusing and I return to Amazon. Read more
Published 12 months ago by Adam N
5.0 out of 5 stars
Amazing Lens
This lens is unbelievable! I bought this to replace my Sigma 70-200mm f/2.8 since it makes more sense on a APS-C sensor. The Sigma lens is stellar. Read more
Published 15 months ago by Jordan Bunch
5.0 out of 5 stars
One of the best current Pentax zoom lenses
This a fabulous lens, and most reviews online would agree with that statement. High quality, fast and well made. The SDM is very nice with my K200D. Read more
Published 16 months ago by Lance D. Ripplinger
5.0 out of 5 stars
Much Better Than Expected - From A Former Zoom Snob
I have just completed a wedding shoot under some of the most challenging lighting conditions. The zoom exceeded my expectations, missing focus only once out of nearly 200 shots! Read more
Published 20 months ago by Christian Vigilia
