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Sigma 17-50mm f/2.8 EX DC OS HSM FLD.

The Sigma 17-50mm f/2.8 is an outstanding professional caliber lens that offers great low light capability, and should satisfy 75% or more of the typical DSLR user's needs. It is a DX lens, designed for Nikon DX cameras, such as the D3xxx, D5xxx, and D7xxx series. It has an internal focusing motor, so all Nikon DLSRs will autofocus this lens. As well, there are versions of this lens for the Canon, Sony, and Pentax mounts.

Incredibly, according to DxOLabs, this Sigma lens beats both the Nikon 17-55mm f/2.8 as well as the Canon 17-55mm f/2.8, and at half the price. This lens is almost a no-brainer to buy for your primary lens if you have a cropped DSLR. The lens is roughly equivalent to a 24-70mm f/2.8 full frame lens, which is the staple of professional photographers.

Sigma 17-50mm f/2.8 EX DC OS HSM FLD Zoom lens Overview

Sigma 17-50mm f/2.8 EX DC OS HSM FLD

Lens Type: 2.9x Zoom
Format: DX (APS-C)
Maximum Aperture: f/2.8
Minimum Aperture: f/22
Focal Length: 18mm to 50mm
Autofocus Type: AF-S
Minimum Focus Distance: 0.9ft
Maximum Field-of-View: 72-27 deg
Filter size: 77mm
Manufactured: Japan
Lens construction: Professional Level
Street Price: $600


Overview: First, what do all of those acronyms mean after the lens number format?

  • EX: High-end professional lens.
  • DC: Dx (cropped) format.
  • OS: Optical stabilization.
  • HSM: Hyper-Sonic Motor
  • FLD: psuedo-Flourite glass to compensate for aberration.

    What makes this a professional-caliber lens? Build quality, lens sharpness, and fast optics. This is a constant f/2.8 maximum aperture lens, which for a zoom lens, is recognized as a low light capable lens.

    For example, consider the entry-level 18-55mm f/3.5~5.6. At 50mm, this lens maximum aperture is f/5.6 - a full 2 stops (2 EV) slower than the Sigma 17-50mm f/2.8. Two stops are huge as it lets in in 4 times more light at 50mm than the entry-level lens. This means you can use a 2 stop faster shutter or a 2 stop lower ISO. You would have to buy a $6,000 DSLR to gain that degree of performance over an entry-level DSLR. So in a nutshell - fast lenses are cost-effective.

    Unfortunately, Neither Canon or Nikon appear to support high-end cropped lenses. They both offer the 17-55mm f/2.8 (of which this lens beats both of them), and that is about it for high-end cropped lenses.

    Testing: How does this lens do in sharpness? One simple way to determine that is to test the lens for optical clarity. While to be more accurate, I should have measured the center and all 4 corners of the lens, this simple test provides a basic idea of the lens performance.

    The test was conducted photographing this scene at different focal lengths; all using an aperture of f/5.6. The yellow box in the lower right is the cropped area for each photo shown below.

    Sigma 17-50mm @ 17mm f/5.6.

    Sigma 17-50mm @ 28mm f/5.6.

    Sigma 17-50mm @ 35mm f/5.6.

    Sigma 17-50mm @ 50mm f/5.6.

    Sigma 17-50mm @ 50mm f/8

    Conclusion: This lens is very sharp when compared to other lenses. If you look at some of my other lens reviews, compare the sharpness of those lenses to this one; especially the entry level Nikon AF-S 18-55mm f/3.5~5.6 at the 35mm focal length. Granted, this is in the corner where it may not be noticeable, but it just shows how sharp the Sigma 17-50mm f/2.8 is.

    If you want the best lens for your cropped DSLR, consider the Sigma 17-50mm f/2.8. When I bought mine, I heard all about the Sigma QC issues, and I was a bit concerned. But I am really glad I put that aside and bought this lens. Perhaps Sigma may have had QC issues in the past, but I would not hesitate to buy this lens over the Nikon 17-55mm f/2.8.

    If you have one of the newer DSLRs with high resolution, you may not achieve all of the performance they can achieve with an entry level lens. These cameras deserve high-end glass such as this Sigma lens. Otherwise, you may not be getting the performance you paid for.