Sigma 17-50mm f2.8 EX DC HSM Optical Stabilised lens for Pentax Digital SLR Cameras with APS-C Sensors

I have been using this lens non-stop for the past 3 years for both photography and film making and I have to say for the price and performance it’s one of the best lenses to use for an APC-S camera body. I was so confident in my initial choice of the lens I bought two, which I use for different functions and it satisfied my needs during those times. Just so you are aware I use a D5500 body along with it, which is known for having 1.5 x crop factor. With that in mind here are the pros and cons.PROs:- It’s versatile as an all-round photography lens. The 17-50mm on APC-S is the focal equivalent to a 24-70 on a full frame camera. At 17mm It is awesome for landscapes/wide angle shots, whilst the 50 mm will behave quite like a 70mm prime for portraits.- Uses a 77mm thread for filter which is common for most fixed aperture lenses- Between the 35-50mm range the lens offers great bokeh for portraits.- Having a fixed f/2.8 aperture is brilliant for low light photography and filmmaking and it feels like you have multiple prime lens. It allows plenty of light onto the camera sensor to keep the ISO & shutter speed at low values.- The auto focus is fast and silent on the D5500 at all focal lengths, and the optical stabilisation is great for capturing sharp images that are stationary or moving.6. Focusing is pretty accurate on wide to medium shots and is useful for manually focussing at infinity if landscape photos are your niche.7. The addition of a lock mode is great to eliminate any breathing when in use or aiming down.8. At f/4-5.6 the images and video produced is super sharp, which is where you should be working from most of the time.CONs:1. The lens is a lot heavier and bulkier than other kit lens to compensate for the fixed aperture.2. The build quality takes a hit due to price reducing. Some people might like the finish others won’t.3. You can feel and hear the internal components move around if you shake the lens and the supplied lens hood can easily fall off.4. The zoom and focus rings are arranged opposite to normal NIKON lens, which can be jarring to new users.5. The manual focus range is extremely limited especially in close up shots, so be aware of the minimum distance you can rack focus to whether in manual or auto.6. At f/2.8 on all focal lengths you can notice the image sharpness gets a bit soft and there is a subtle vignette at the lower focal length range.7. The focal length zoom is an external rather than internally function which isn’t great for filming unless the camera is station at all times.Considering most people who are looking at this len probably are starting out with either/both the 18-55 Nikon kit lens and Tamron 70-300 VC, this of course is the natural progression to advancing your photography. Along with the NIKON 35 mm and 50mm prime lens this would be among my go to lens if I started again from scratch.As a film maker or vlogger, I will admit it might not tick all the boxes and that’s in part due to the negatives addressed. If you really are on a tight budget by all means go for it, but if you’re going to do it professionally I’d often recommend saving the money and getting the sigma art 18-35mm f1.8 and future proof the investment.Regardless of the negatives I still love this lens as it is overall a good purchase, it’s ideal for travel being an all-around lens and can produce truly stunning images with minor issue being fixable in post. I absolutely would recommend this.

Lens is much better than I expected, I initially wanted the nikon version to use at weddings, however I couldn't justify the cost and was a little disappointed that I had to go for this version.After reading so many reviews and doing so much research into this lens the nikon 17-55 and the Tamron version I ended up choosing this one out of the 3.I am so glad that I did, the build quality for this lens is much better than I expected the zoom ring feels very tight and solid and the front element looks very nice.The only thing missing ergonomics wise is the old EX texture to the lens that sigma used to coat there lenses with which I was a fan of, this however doesn't impact the performance of the optics which are simply brilliant even wide open right across the focal range, its certainly an upgrade to any kit lens.I read a couple of reviews stating that is soft wide open, granted all lenses will be softer wide open however this isn't really noticeable and I certainly don't notice the difference if I'm not looking at Exif data.I would like to point out that this was based on centre sharpness.Border sharpness is slightly lower than the centre which is not an issue if you stop down, this isn't really as big a deal as some reviews/people make it out to be as in practice I only shoot portrait wide open and the boarder is usually out of focus anyway (due to depth of field effect) You would naturally stop down for landscape shots anyway thus bringing the entire frame into sharp focus including the boarders.I haven't really taken this off my D90 since buying it as the OS, coupled with the F2.8 constant aperture is very good for shallow Depth of field and low light portraits, so much so that I don't bother with my 50mm prime any more and I have sold it as a result.My only niggle is that Nikons Silent Wave autofocus system has full time manual override whereas this version of HSM doesn't as the focus ring moves on autofocus.All in all thought, this is a surprisingly very good lens which is incredibly sharp, useful low light and an excellent portrait lens I am unable to understand why the Nikon is so expensive when this is as good as it is for the cost (even comparing nikons non VR to cannons IS version threes almost 50% cost difference)

My first impressions;I may update and do a more in depth review later as I have only used this lens in Theatre lighting, which is a unfair test for most lenses.How did it perform?The contrast is very good likewise so is the colour reproduction accurate, but what about sharpness?Well not the sharpest lens in my kit, but then it's competing with Sigma Art lenses so perhaps it's an unfair comparison especially considering the price point.Theatre lighting is both contrasty and often oversaturated often in the reds and blues add to this that light comes from many directions and only the wide angle hood is the only protection against stray light.So considering all of the above, I would say the lens performed well in contrast, focus, and sharpness, I would digitally zoom to 1.6x before softness became obvious.The lens was mounted on a Canon R7 recording video at 4k and left un-attended as a wide stage shot only, for this purpose the Sigma 17-50mm worked well, but if I ever move to outputting my videos in 4k instead of HD, then this lens may not be up to the job.I do suspect though that used in stronger natural light this lens would achieve better results, so will give an update later.Do bear in mind that this is an earlier generation lens so image stabilisation is a bit sluggish, and you can clearly hear the focus motor at work, which where common with most lenses around 10 years ago.Is it worth the money, even on the demanding R7, under better lighting conditions, I believe this lens would stand up well to todays lenses as far as image quality goes, so if you are looking for a fast all rounder for your crop sensor camera, then give this one some consideration.