Sigma 17

The Sigma 17-50milimet f/2.8 EX DC OS HSM Lens features a nice range of focal lengths, a wide f/2.8 aperture, HSM autofocus và OS (optical stabilization) in a well-built andreasonably-priced lens.

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Most of us need at least one general purpose lens - và the focal length range is usually my primary qualification for such a lens.The 17-50mm focal length range falls squarely in the recommended general purpose lensfocal length range for the APS-C sensor format DSLRs it is compatible with.

This focal length range delivers that same angle of view that a 27.2-80milimet lens on a full frame DSLR would deliver,but again, this APS-C-only lens is not compatible with the larger format SLRs.Here is an example of what this focal length range looks like.

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17mm | 18mm | 20mm | 25milimet | 30milimet | 35milimet | 40milimet | 45mm | 50mm

My field work for the Sigma 17-50mm f/2.8 EX DC OS HSM Lens Review was done in early spring.After a long, cold winter, the bright new growth on the trees was looking gorgeous lớn me.The 17-50mm focal length range is nice.It works great for around-the-house shots (inside and out), for landscapes, for full body toàn thân & head-and-shoulders portraits, for cchiến bại sports và for a huge range of other uses.

For many, their first general purpose lens is the one available in-the-box with their first DSLR.While the kit lens is very economical, it is also the source of many emails I receive - especially when being used indoors without a flash.If there is any subject movement, the max aperture available on these lenses is not wide enough to allow the action khổng lồ be stopped - resulting in motion-blurred images.

The Sigma 17-50 OS" fixed f/2.8 max aperture across the entire focal length range provides 4x as much lightto the sensor (2 stops) as most kit lenses offer at their longest focal length (f/5.6).This aperture difference can translate into lớn a big difference in your image chất lượng.

There are many lenses with longer focal length ranges available.The longer focal length lenses frequently sacrifice image chất lượng to lớn obtain their range and most do not offer the fixed f/2.8 max aperture across the entire range.There are, however, many 17 to lớn 50mm (or 55mm) f/2.8 lenses available from other manufacturers - I"ll reference some of these later in this Review.

As I indicated already, a wide aperture is a great advantage for a lens to lớn have.Use the wide aperture to stop action (or camera motion) in low light by allowing a faster/shorter shutting tốc độ and/or to lớn blur the background.(a wider aperture results in a shallower depth of field - all other factors remaining equal).At 17milimet, you are going to need a cchiến bại subject to lớn generate any significant background blur at 17milimet f/2.8,but, at 50milimet, blurring the background becomes an easier accomplishment.

If your subject is not moving, the Sigma 17-50"s 4-stop-rated OS (optical stabilization) will be a great help in achieving sharp handheld shots in low light,in the wind, on unstable footing, on a boat ... và in other situations where holding a camera steady is difficult & a tripod is not being used.

At 17milimet, I am getting a good rate of sharp images from the Sigma 17-50milimet f/2.8 EX DC OS HSM Lens at 1/4 sec exposures for a net 3-stops of assistance from OS.I have sầu some sharp shots taken at .6 and .8 seconds, but the keeper rate is very, very low at these exposure durations.At 50mm, 1/10 or 1/8 seems lớn be my shutter speed limit for sharp images.This is, again, a net 3-stops of assistance from OS.I have sầu a couple of sharp images made at 50milimet và 1/5 sec, but the keeper rate is very low.

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The Sigma 17-50mm f/2.8 EX DC OS HSM Lens is shown mounted on a Canon EOS 60D above sầu.

With a wide open f/2.8 aperture, the Sigma 17-50mm f/2.8 EX DC OS HSM Lens is impressively sharp in the center throughout the focal length rangewith 50milimet showing very slightly reduced sharpness.The corners are soft at f/2.8 with the 50milimet corners looking the best.Stopping down does not significantly affect the center of the frame image chất lượng - nor does it need khổng lồ.

By f/5.6, corners show a little improvement overall và improvements are again realized at f/8.Stopping down at 50milimet, the center shows slightly more improvement & the corners show somewhat less improvement than the rest of the range -due lớn the slightly worse/better 50milimet f/2.8 center/corner sharpness.At f/11, diffraction begins lớn show - reducing image sharpness over most of the frame (though corners continue lớn improve).

The Sigma 17-50 OS controls vignetting quite well.With a wide open aperture, expect to lớn see about 1.5 stops of peripheral shading in the corners at the two focal length extremes with noticeably lessin the mid focal lengths.Stopping down to lớn f/4 reduces the corner shading to lớn about 1 stop at 17milimet & about .8 stops remain at 17mm even at f/11.chú ý that a normal thickness circular polarizer filterwill add a small amount of mechanical vignetting at 17milimet - even at f/11.

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Some chromatic aberration is noticeable in the corners in the wider half of the focal length range.As a generalization, CA is worst at 17mm và slowly improves through the balance of the focal length range.The amount of CA exhibited is not unusual for a lens in this class.

The Sigma 17-50 OS shows varying amounts of flare over the focal length và aperture ranges, but overall, it is a decent performer in this regard.Bokeh (background blur quality) generated by the 7-blade aperture appears to lớn be mid-grade.The odd number aperture blade count will create 2x the number of light rays as aperture blades (14) from points of light when a narrow aperture is used(even blade counts deliver 1x light rays).

At 17milimet, the Sigma 17-50 exhibits a noticeable bulge-in-the-middle barrel distortion.This distortion smoothly transitions lớn mild pincushion distortion at 50milimet with approximately 25mm being the near-distortion-free transition focal length.

Overall, I"m pleased with the Sigma 17-50mm f/2.8 EX DC OS HSM Lens" image unique, though the corner sharpness is the most lacking piece of the overall image quality puzzle.

The Sigma 17-50 OS incorporates Sigma"s (Hypersonic Motor) for moderately fast autofocusing.Though reasonably quietly, the 17-50 generates some gear noise during AF.Focus accuracy has been the biggest issue I"ve encountered with this lens.I"ve had many shots misautofocused for no apparent reason - especially in AI Servo mode.

Focusing is internal - the front element does not extover or rotate.Expect a relatively small amount of focus breathing from this lens - the subject/framing changes kích cỡ a small amount when focusing.

FTM (Full Time Manual) focusing is not featured in this HSM AF implementation - the focus ring turns during AF.A printed-on-the-MF-ring focus distance scale is provided - and reveals the lack of FTM.

The focus ring is nicely sized và in the position I prefer - as the front-most ring.The Sigma 17-50 focuses smoothly, but with a relatively short 42° rotation và low rotation resistance, precise focusing is touchy.

The table below reviews a large number of general purpose lenses" minimum focus distances and maximum magnifications.

ModelMFDMM
Canon EF-S 15-85milimet f/3.5-5.6 IS USM Lens13.8"(350mm)0.21x
Canon EF-S 17-55mm f/2.8 IS USM Lens13.8"(350mm)0.16x
Canon EF-S 17-85milimet f/4-5.6 IS USM Lens11.8"(300mm)0.20x
Canon EF-S 18-55milimet f/3.5-5.6 IS II Lens9.8"(250mm)0.34x
Canon EF-S 18-135milimet f/3.5-5.6 IS Lens19.3"(490mm)0.21x
Canon EF-S 18-200milimet f/3.5-5.6 IS Lens17.7"(450mm)0.24x
Sigma 17-50milimet f/2.8 EX DC OS HSM Lens11.0"(280mm)0.20x
Sigma 17-70mm f/2.8-4 DC Macro OS Lens8.7"(220mm)0.37x
Sigma 18-125milimet f/3.8-5.6 DC OS HSM Lens13.8"(350mm)0.26x
Sigma 18-200milimet f/3.5-6.3 DC OS Lens17.7"(450mm)0.26x
Sigma 18-250mm f/3.5-6.3 DC OS HSM Lens17.7"(450mm)0.29x
Tamron 17-50mm f/2.8 XR Di II Lens10.6"(270mm)0.22x
Tamron 17-50milimet f/2.8 XR Di II VC Lens11.4"(290mm)0.21x
Tamron 18-200mm f/3.5-6.3 XR Di II Lens17.7"(450mm)0.27x
Tamron 18-270milimet f/3.5-6.3 Di II VC Lens19.3"(490mm)0.29x

With an 11" (280mm) MFD and a .2x MM spec, the Sigma 17-50mm f/2.8 EX DC OS HSM Lens is not a svào contender in the close-up competition.But, these specs are in line with the other 17-fiftysomething f/2.8 lenses.And, these figures are good enough for many cthua thảm subject needs.

However, that is not the over of the close-up story.The tested MFD for this lens is 9.17” (233mm) which should equate khổng lồ about .24x MM.MFD testing uses manual focusing - and this lens indeed manually focuses closer than it will autofocus.

As I mentioned in the beginning of this đánh giá, the Sigma 17-50milimet f/2.8 EX DC OS HSM Lens has very good build unique.I have not been a big tín đồ of Sigma"s matte finish - especially because it readily shows fingerprints và dust.The good news is that only the edges of the zoom and focus rings retain the conventional Sigma finish.The hood & mount areas, the main lens areas not covered by rubber zoom or focus ring, are a much nicer (my opinion of course) smooth finish.

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The focus và zoom rings are very smooth with no play.The zoom ring has an ikhuyến mãi amount of resistance while, as I indicated earlier in the đánh giá, the focus ring is slightly too easy khổng lồ rotate.


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