Đánh giá tamron 17-50 và sigma 17-50
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On full frame cameras the 24-70mm f2.8 lens is the go-to lens for travel, sports, wedding, street, and landscape photography. On cropped sensor cameras the equivalent focal length to a 24-70mm is roughly 17-50mm. This latter focal length gives you wide, normal and telephoto lens perspectives in a relatively small package that fits on cropped sensor cameras. If you are looking for a fast all-purpose lens for your Canon camera whether a Rebel, 20D, 30D 40D, 50D, 60D or the 7D, then you have four choices: Note: To see all future reviews please note this blog is no longer active, please visit me over at oopoomoo.com Canon EF-S 17-55 f2.8 IS USM
Sigma 17-50mm f2.8 EX DC HSM OS
Tamron 17-50mm f2.8 XR Di II VC
There is also the Tokina 16-50mm AT-X 165 Pro Dx but I did not have an opportunity to test this lens. A Bit of History When I picked up my first cropped sensor Canon camera (a Rebel Xsi) I wanted a light, fast lens for hiking and backpacking. I tested out the Tamron 17-50mm lens (the f2.8 XR di II LD versionwithout the vibration compensation feature). I found it to be surprisingly sharp and I picked up a new one for a sale price of $350 CAN! It was perfect for landscape photography especially for me because I almost always use live view and manual focus on the Rebel to make landscape images. I owned the lens for a year or so and took many landscape photos with it in all sorts of conditions. It was a super performer for the price! But… be aware that the Tamron lens is really lacking as an auto-focus lens. It was painfully slow to focus and was noisy when focusing. I tried using it with dogs and sports and it was not really suited for action photography. ©Darwin Wiggett - Tamron 17-50 f2.8 lens ©Darwin Wiggett - Tamron 17-50mm f2.8 lens And Then… Sigma sent me their 17-50mm f2.8 lens to try it. I was incredibly happy with the Tamron in terms of sharpness and so my first tests were to see if my budget priced Tamron was as sharp as the more expensive Sigma lens. I did the standard tests in the studio using a lens chart to check sharpness at all apertures and at various focal lengths. And then I took the lenses out in the field and photographed the typical kinds of subjects that I shoot to see how the lenses performed in terms of contrast (snap) and colour rendition and also things like flare control and distortion. Rather than bombard you the reader with tons of detailed comparison shots the conclusion of all these tests was the same. Both lenses performed the same optically but with the nod going to the Tamron in the 17-35mm range at f2.8 (better edge sharpness). ©Darwin Wiggett - Sigma 17-50mm lens at f14 But… the Tamron was terrible auto-focus performer! I’ve found that using live view at 5x magnification and manually focusing lenses gives me much sharper images than using auto-focus even in bright contrasty light. This result is consistent across cameras I have tried from the Canon 1ds Mark III, Canon Rebel Xsi and Rebel T2i, Canon 60D, Canon 7D and the Nikon D300s. On workshops and tours I often illustrate this to participants using their own cameras. To try it yourself, simply set your camera to aperture priority and use the smallest number on your aperture dial like f2.8. Use the center focus point on your camera and let the camera focus on a contrasty part of the subject. Now go into live view and magnify the area (e.g. 5x) where the camera auto-focused. Switch your lens to manual focus and adjust the focus to see if you can get the image sharper than the auto-focus. Often you can easily improve on the sharpness. Check out the scene below. I had the Canon Rebel Xsi mounted on a tripod and the auto-focus was set to ‘one shot’ with the center focus point selected. I had the aperture set to f2.8 and let the camera auto-focus. Then I rephotographed the same scene using manual focus in live view. The auto-focus test scene Below are the results of the test using the Sigma 17-50mm lens at f2.8. The image is magnified to 100% view. The top photo is auto-focus, the bottom is manual focus in live view. Sigma 17-50 at f2.8: top=auto-focus, bottom=manual focus in live view The auto-focus on the Sigma/Rebel combo locked in really well. The manual focus is a tad sharper but not by much. Below are the results of the Tamron lens on the Rebel Xsi: Tamron 17-50 f2.8: top=auto-focus, bottom=manual focus in live view What can you say? The auto-focus on the Tamron lens is terrible! It is slow, it searches, it hunts, it creeps, it’s noisy. I have tested and tried several Tamron lenses (from their 70-200 f2.8 to their 10-24mm lens) and the problem is the same. If, like me, you mostly use manual focus and a tripod, then the Tamron is easily the best buy of the group (especially the non VC version of the lens) and optical performance is really fine. But if you want a sports, travel, portrait lens where you can rely on auto-focus, then I would pass on the Tamron. Also note I did not test the vibration compensation (VC version) of this lens, other reports on the web suggest that sharpness of the VC version is lower than the non VC version. Test before buying! And so, after testing the Sigma 17-50 f2.8 against the Tamron lens, I decided to sell the Tamron and keep the Sigma. The Sigma was just as good optically (except at f2.8 where edge sharpness was lower) but it had fast and accurate auto-focus and it had optical stabilization for hand-held shots. And So What About the Canon 17-55mm f2.8? This is Canon’s flagship lens for cropped sensor cameras and numerous reports state that this lens is super sharp and an all around great performer but it comes at a high price ($1200 CAN). Is the overall quality and performance of the Canon worth the extra cost (more than $400) over the Sigma? I took the two lenses out over a weekend and ran them through a few tests such as:
Here is what I found: Optical Performance I compared the sharpness of both the Sigma and the Canon lenses using manual focus in Live View. When precisely focused I really could not give the nod to one lens over the other when it came to center sharpness at all focal lengths and apertures. But at f2.8 in the focal range of 17 to 35mm the Canon had significantly better edge sharpness than the Sigma. Edge sharpness at 17mm at f2.8 (Sigma top, Canon bottom) It’s easy to see here that the Canon lens is really good wide open even at the edges. The Sigma lens does not match the edge performance of the Canon until stopped down to f8! After f8 the two lenses perform equally well. Another weakness of the Sigma Lens are fringing artifacts at the edges of the frame when the lens is shot from 17- 35mm in high contrast light. The Canon also suffers these effects but to a lesser extent. Edge fringing at f2.8 at 17mm - Canon top, Sigma bottom The fringing on both lenses is more controlled and equal once the lenses are zoomed out to 35mm or higher. The Canon lens appears to be optimized for best performance in the aperture range from f2.8 to f8. Images at f11 are decent but less sharp overall and images at f16 or higher are terrible! Canon 17-55 at f5.6 (top) and f22 (bottom) I found that although center sharpness on the Sigma is as good as the Canon at f2.8 and f4 that overall image sharpness from edge to edge is best with the Sigma in the f5.6 to f11 range with good performance up to f16. The Sigma is better than the Canon in the f11 to f16 range and therefore is a better choice for landscape work requiring large depth-of-field. Sigma lens at f16 top photo, Canon lens at f16 bottom photo The Sigma lens also records images with more contrast and ‘pop’ and with a more accurate colour cast than the Canon lens which tends to record scenes flat and washed out and cool in colour tone. Sigma lens top photo, Canon lens bottom photo Sigma lens top photo, Canon lens bottom photo In numerous tests I found this same difference in contrast and colour between the two lenses. All comparisons were shot at the same exposures, white balance etc. The Sigma lens simply had a more pleasing rendition of scenes for my tastes. As far as flare is concerned it depends. Sometimes the Sigma gave more flare (e.g. at 17mm) sometimes the Canon was more prone to flare (e.g. at 28mm). Auto Focus Tests I tested both the Sigma and the Canon lens for accuracy of auto-focus vs manual focus in live view and both lenses returned similar results. Live view gave slightly better results for both lenses. Only in dim light did the auto-focus capabilities start to falter. With action sequences of people running, cars on the highway and moving dogs, I saw absolutely no difference in the ability of the Sigma and Canon lenses to track focus. As well, with static subjects both lens were zippy and fast to auto-focus and for me they seemed matched in their abilities. Image Stabilization Tests Handheld images using auto-focus and image stabilization (Canon) and optical stabilization (Sigma) returned fairly similar results but I got a slightly higher percentage of sharp shots in the 1/15th to 1/30s range with the Canon lens. So nods in this department to Canon. Close-focus Capabilities The clear winner in this category is the Sigma lens. Not only does it focus closer (see images below) but when photographing close subjects (e.g. head and shoulders or closer, the Sigma is significantly sharper at all apertures than the Canon lens. The Canon does not seem to like close subjects and optical performance really suffers. This is not a good lens to use for close-up work! sigma at closest focus at 50mm Canon closest focus at 55mm Sigma close detail sharpness at f8 Canon close detail sharpness at f8 Conclusion Which lens you choose all depends on your budget and on your needs. If want the best overall optical performance for your dollar then the Tamron SP AF17-50 f2.8 Xr Di II is a fantastic buy! Although I did not this test the lens directly against the Canon lens, I think it is just as sharp at all apertures but it costs almost 1/3rd the price of the Canon lens! But the Tamron is not a lens to buy if you rely on auto-focus. This is a good landscape lens when used on a tripod and focused manually in live view. But do not try action photos with this lens or you’ll be disappointed. If you want a lens with good all around performance at the a reasonable price, then the Sigma 17-50mm f2.8 lens might be the lens for you. The Sigma is as good as the Canon lens in terms of auto-focus, it’s a sharp as the Canon lens when stopped down to at least f5.6 and it is a much, much better lens for close-up subjects. As well the contrast on the Sigma lens is snappy and the colour rendition is accurate. The Sigma is a better landscape lens than the Canon because it has better performance in the f11-f16 range which are apertures often needed for depth-of-field. Also the lens is the lightest of the bunch. I would recommend this lens for nature and generic photography. If you want to photograph people, sports, or action or hand-held street photography where wide apertures like f2.8 or f4 are regularly used then the Canon 17-55 f2.8 lens lens is the best choice. It’s sharp edge-to-edge when wide open (with little fringing), has great image stabilization and zippy auto-focus. The drawbacks are its heavier weight, poor close-focus performance, flat contrast and cool colour rendition and large price tag. In short, none of these lenses are perfect but some work better for some purposes than others. As always try before you buy but hopefully this review will help narrow your choices. ©Darwin Wiggett - Sigma 17-50mm lens at f11 This entry was posted on May 9, 2011 at 12:33 PM and is filed under Lens Review, Photography Gear, TCBlog with tags 17-50mm lens, Canon, Canon lenses, fine art photography, landscape photography, lens review, nature photography, Photography, portrait photography, Sigma Lenses, Stock Photography, Tamron lenses, Tokina lenses, Travel Photography. You can follow any responses to this entry through the RSS 2.0 feed. You can , or trackback from your own site. |
