Canon EF-S 15-85/3.5-5.6 IS USM Review

The canon_15-85is was introduced in 2009 as a replacement for the canon_17-85. In addition to the extra 2mm of focal length on the wide angle end of the range the lens was optically redesigned, adding 2 more aspheric elements and one UD element. This results in increased performance – though unfortunately also in increased cost.

Since it’s an EF-S lens, the 15-85IS will only mount on Canon crop sensor cameras such as the EOS 7D and Digital Rebel T2i. On a crop sensor camera it covers the same field of view as a 24-136mm lens would on a full frame DSLR. This is an excellent range for a general purpose lens, making it useful for everything from wideangle landscapes to closeup portraits and everything in between. For photographers who don’t like switching lenses and don’t need long telephoto reach, this lens might be the only one they need.

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Photo.net’s partners have the Canon 15-85mm f/3.5-5.6 IS USM available. Their prices are fair and you help to support photo.net.

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Image Quality

The difference in image quality between the older EF-S 17-85IS and the new 15-85IS is most noticeable when looking at the edges and corners of the image at the widest settings. The sample images on the right are 100% crops of images shot with the two lenses using an 18MP Digital Rebel T2i. which (along with the EOS 7D) is the crop sensor DSLR body with the highest sensor resolution You can see that the 15-85 images is sharper and shows less chromatic aberration then the 17-85 image. The 15-85 has two additional aspheric lenses, which should improve wideangle off-axis performance and a UD element which should help in the control of chromatic aberration. It appears that they are effective in both functions.

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In the center of the image and at longer focal lengths, the difference between the image quality of the 15-85is and 17-85is is much smaller. On the right are 100% crops from the center of images shot with a Digital Rebel T2i. I think the 15-85 shot is very slightly sharper, though the two images are very close, even at this extreme magnification. It is easier to produce high quality imaging in the center of the frame since most aberrations increase as you move off the optical axis of the lens, so it’s not too surprising that both lenses are similar in center sharpness. Similar sharpness is seen in the center of the image at 17mm where the difference between the two lenses is again fairly small.

Out at the extreme left edge of the image at 85mm the situation is as shown on the right.

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The top image from the 17-85 is slightly softer than the center image from the 15-85, but it seems that the extra sharpness of the 15-85 makes the chromatic aberration seem more intense. This CA can be corrected using DPP as shown in the bottom image.

In general CA seems most visible at the focal length extremes (around 15mm and 85mm) at intermediate focal lengths it seem better controlled.

This can be seen when looking at the edges of shots taken at 35mm. With the EF-S 15-85is there is very little CA visible as can be seem in the upper shot of the image samples shown on the left.The lower shot is from the EF-S 17-85is and you can see visible CA as well as a softening of the image compared to the shot taken with the 15-85is.

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In the center of the frame at 35mm the image quality of shots taken with the two lenses was very similar.

Vignetting is also fairly well controlled, as it should be for a relatively slow lens designed for a crop sensor camera. It’s most noticeable when shooting wide open at 15mm where there’s about a 2-stop falloff in the corners of the image, reducing to about 1 stop by f5.6. At focal lengths above 20mmm there’s about a 1 stop falloff wide open.

Distortion

Like the older 17-85is, the new 15-85is shows significant barrel distortion at wideangle settings. The images on the right show the degree of distortion at 15mm.

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The upper image shows the distortion as shot, while the lower image is the same shot (in RAW) processed via Canon’s DPP software with distortion correction applied. Distortion drops rapidly as the lens is zoomed out an it is pretty much gone by 20-24mm. At longer focal lengths there is a very small amount of pincushion distortion.

In general, distortion is most noticeable when shooting subjects with vertical and horizontal lines near the edges of the image, such as the example of artwork shown here. It tends to be much less noticeable in landscapes and images where lines are mostly diagonal.

Specifications


Focal Length 15 – 85mm
Max Aperture f3.5 – f5.6
Lens Construction 17 elements in 12 groups
Diagonal Angle of View 84° 30’ – 18° 25’
Focus Internal focusing system with USM
Close Focus 1.15 ft./0.35m
Max Magnification 0.21x
Filter Size 72mm
Diameter 3.2" (81.6mm)
Length 3.4" (87.5mm)
Weight 20.3 oz. (575g)

Conclusion

The canon_15-85is is an improvement over the lens it replaces, the canon_17-85. Image quality has been improved via the use of two additional aspheric elements and one UD element. The difference is most noticeable at the edges and corners of the image at wide angle settings, where the image is sharper and shows lower chromatic aberration. There is less difference in the center of the image and at longer focal lengths. The additional 2mm at the wide end of the range is also welcome.

Of course it still suffers from being rather slow, especially at the long end of the range, and like the 17-85, barrel distortion is quite strong at the wide end of the zoom range and there is some vignetting wide open at all focal lengths. However taken overall, the EF-S 15-85 is still a strong contender for anyone who wants one lens that covers a wide range and can be used for everything from landscapes to portraits. It’s also fairly small and light making it an ideal traveling companion, especially if combined with a small and light DSLR like the new Digital Rebel T2i.

The EF-S 15-85/3.5-5.6 is a little slow, especially at the telephoto end of the range. However if you want a similar lens with a faster aperture you can get the canon_17-55. The optics are slightly better, but it will cost you significantly more and you won’t have as large a zoom range so you have to compromise between cost, quality, speed and zoom range.

Where to Buy

Photo.net’s partners have the Canon 15-85mm f/3.5-5.6 IS USM available. Their prices are fair and you help to support photo.net.

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Canon EF-S 15-85/3.5-5.6IS USM Sample Images

10916387 The EF-S 15-85IS is quite useful for semi-closeups, though of course it’s not a macro lens.Maximum magnification is about 1/5th life size (0.21x) at the 85mm setting. This shot was taken at a 63mm focal length, f11 and at ISO 800 using a Digital Rebel T2i.
10916381 Despite the barrel distortion at 15mm, it’s not really noticeable in many wideangle shots. Unless you have vertical and horizontal straight lines near the edges of the frame, the distortion may not be evident to most viewers. This shot was taken at 15mm and no distortion corrections have been made.

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    • Thank you, Bob, for your as always interesting and honest review.

      It might be interesting to compare this general purpose lens for crop sensor cameras with the "parallel" general purpose lens ( EF 24-105 f4 IS) for full frame cameras....

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    • Based on this review and my own experience with the 17-55 EFS with fixed 2.8 aperture, I would stick with the latter.  I think this lens could struggle in the retail market.

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    • As a retired professional, I'd like to through my $.02 worth into the mix.  The lens is less than $1000, and not necessarily intended for professional use (largely, owing to the aperature and the durability).  Having said that, the elements on the inside make it perfectly capable of rendering beautiful images for any publication, or for printing. 

      With digital, so much of the control of the output is in post.  I would hands down take this over the previous version.  The elements are better, the build quality is the same or better.  I recently bought this lens for travel, a trip down the California coast from San Fran to LA.  Did I use the lens at 15?  About 70% of the time. 

      As it has been pointed out, in landscape the lens at 15mm produces great images, and if you want to correct any aberations, use Canon's software that comes with any number of their EOS cameras.  If you want to shoot architecture, properly, buy a large format.  It's a great lens, not the only lens to have if you have varied photgraphic interests, but one that will cover a lot of bases.

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