Review Sigma 17-50mm F28 Ex Dc (Os)* Hsm
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Review past Klaus Schroiff and Markus Stamm, published May 2013
Introduction
Over many years Sigma struggled to accept off in the fast standard zoom arena for APS-C DSLRs. That segment had been dominated by the Tamron AF 17-50mm f/ii.8 (VC) with its highly attractive price/performance ratio and the all mighty simply expensive OEM offerings (Nikon AF-South DX 17-55/2.8 and Canon EF-S 17-55/ii.8 IS) owning the quality crown. However, with the release of the AF 17-50mm f/2.8 EX DC HSM Bone in 2010, Sigma finally offers a lens that is able to compete in this loonshit.That alone may not exist all THAT heady - we've seen many fast standard zoom lenses by Sigma come up and go - but this one is a bit more special. Within the recent years, Sigma announced a couple of lenses featuring their new FLD glass and the new 17-50mm f/2.8 Os is amongst them. FLD glass has an optical characteristic similar to fluorite glass. Such glass elements tin can be used to compensate optical aberrations (defects) more efficiently than conventional "special" elements such as Sigma's more usually used SLD drinking glass. We were already very impressed by the performance of the Sigma AF 8-16mm f/iv.5-5.half-dozen DC HSM which likewise benefits from FLD elements then there's some well founded promise that the AF 17-50mm f/two.8 EX DC HSM OS stands out from the ordinary as well.
And then, let'due south have a await at how the lens performs on our current DX test camera, the Nikon D7000.
The build quality of the Sigma lens is pretty expert although information technology stays a little short of the loftier expectations that we associate with a Sigma EX ("Excellence") lens. It'due south fabricated of tightly assembled combination of metal and high quality parts so at that place's nothing wrong here.
Like its predecessor (AF 18-50mm f/2.8 HSM DC EX macro) it uses a mono-cam organization (i inner lens tube) to extend the lens when zooming towards the tele setting. The front chemical element does not rotate. The zoom ring has a polish, pleasant activity whereas the focus ring has basically no friction in manual mode. The focus ring is coupled to the AF mechanism and so it rotates during autofocus - this is somewhat disappointing for a high end production.
The 17-50mm f/ii.8 EX DC HSM OS features the slightly simplified version of Sigma'south HSM ("hypersonic AF motor"). It is still fast and about silent just total-time transmission (FTM) override is not possible in unmarried-shot AF mode. All the same, thank you to HSM the lens is fully compatible with all Nikon DSLRs, including the entry-level models.
Both the zoom and the focus ring piece of work in "Canon" style, which is the exact contrary of how these rings work on Nikkor lenses. If you're used to the Nikon way of zooming information technology may take a while to feel comfy with the Sigma. And if yous endeavour to focus manually, you'll have to remember that the focus assist in the viewfinder assumes a Nikon lens and consequently suggest the incorrect direction of focus band movement. However, manual focusing is delicate due to the extremely brusque focus path - it only takes a plough of ~thirty degrees to focus from infinity to the close focus limit. This approach improves the AF speed for certain but y'all need to have some haptic skills if you desire to do it all manual.
An important feature is, of course, the Bone ("Optical Stabilizer"). Equally already reported in previous reviews information technology is impressively efficient and as expert as the respective genuine manufacturer implementations. Sigma claims a gain of four-stops which seems to fit here based on our field impressions.
| Specifications | |
|---|---|
| Equiv. focal length | 25.v-75 mm (full format equivalent) |
| Equiv. aperture | f/4.ii (full format equivalent, in terms of depth-of-field) |
| Optical construction | 17 elements in 13 groups inc. 2 FLD and two aspherical elements, 2x LD (Low Dispersion) glass element, 2x XR (Extra Refractive) element |
| Number of discontinuity blades | 7 (rounded) |
| min. focus altitude | 0.28 g (max. magnification ratio 1:five) |
| Dimensions | 83.5 x 91.8 mm |
| Weight | 565 one thousand |
| Filter size | 77 mm (not-rotating) |
| Hood | supplied, petal-shaped, bayonet mountain |
| Other features | HSM (Hypersonic AF), Bone (Optical Image Stabilizer) |
Source: https://opticallimits.com/nikon--nikkor-aps-c-lens-tests/838-sigma175028os
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