Canon Ef 85Mm F/1

(From Canon lens literature) A highly practical medium telephoto lens with superb delineation và portability. Images are sharp and clear at all apertures. Through computer simulations, the lens has been designed lớn give beautiful background blur. Since the front lens group does not rotate during focusing special filter effects are not affected.

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Test Notes, Canon 85mm f/1.8 USMby Jim Tanner

Prime lenses in this focal length range have always been great choices for portrait photography, because of the tendency of the moderate telephoto focal length khổng lồ slightly "flatten" facial features, avoiding the problem of too-big noses in frontal shots taken with wider-angle lenses. In the digital era (at least with sub-frame cameras), the 85mm focal length of this lens gets a little long for that usage (you"ll kết thúc up having to stand off quite a distance from your model), but the favorable effect of a long focal length continues to make the attractive choices for that sort of work. In fact, the Canon 85mm f/1.8 USM seems to be almost ideally suited for portrait shooting, as its very wide aperture really helps to lớn blur out distracting backgrounds, và its soft corners (which might otherwise be considered a defect) can help to isolate a portrait subject near the middle of the frame. While far from a perfect optic, the 85mm may be one of the better portrait lenses on the market: Read on below for all the details from our testing.

Be sure to check out the Blur Viewer shown to the right of this report, which shows the detailed blur performance of this lens on our sub-frame Canon EOS-20D body. The plot first displayed when you bring up the viewer (f/1.8) reveals a slightly soft center & softer corners. As you move the aperture slider to show performance at smaller apertures, you will notice that the center sharpens a bit while the corners sharpen more, until the plot becomes relatively flat at f/4; then remaining so throughout the remainder of the aperture range. The Full Frame (5D) Blur Viewer reveals even softer corners on the 5D, a result of the larger sensor capturing corner detail much farther from the center of the frame. These observations will be expanded upon in the two sections (Center Sharpness, Corner Sharpness) immediately below.

Center Sharpness

Center Sharpness for the Canon 85mm f/1.8 on both the Canon 20D & 5D are shown in Figure 1 to lớn be very similar. Using DxO"s Blur Scale, the center portions of the images are "Sharp" in the f/2.8-f/16 range. Diffraction degradation renders the f/22 centers to lớn be "Slight Blurred" for this lens. At f/1.8 and f/2, the images are also "Slightly Blurred". All in all, the Center Sharpness for the Canon 85mm f/1.8 lens is very good.

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Corner Sharpness

While Center Sharpness is very good for the Canon 85mm f/1.8, Corner Sharpness at wide apertures is not! Figure 2 reveals this only too well. At f/1.8 & f/2, the corner performance shows excessive blur on the 20D & the 5D. & at f/2.8, corner performance on both bodies gets a "Visible Blur" raring. From f/4 on, Corner Sharpness on both bodies falls in the "Sharp" khổng lồ "Slightly Blurred" range. Summarizing, Corner Sharpness for the canon 85mm f/1.8 lens is poor at the wider apertures và satisfactory thereafter.

(As noted in the introductory paragraph above though, the pronounced softness in the corners may actually be a benefit for some types of shooting, portraits in particular.)

Chromatic Aberration

On the Canon 5D, the Canon 85mm f/1.8 lens exhibits quite acceptable Chromatic Aberration, while the CA performance on the Canon 20D is more nearly average. The Chromatic Aberration characteristics of the Canon 85mm f/1.8 lens are perhaps slightly better than average overall.

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Shading ("Vignetting")

Shading performance by the Canon 85mm on the sub-frame 20D is excellent from f/2.8 through f/22. The larger full-frame sensor of the Canon 5D reveals some higher shading for the wider apertures, but for f/5.6 and higher apertures, the Shading performance by the Canon 85mm on the 5D is quite acceptable. The Shading performance by the Canon 85mm f/1.8 merits a better-than-average rating for sub-frame cameras, a poorer-than-average rating for full-frame ones. (Again, this shortcoming may actually be a benefit for applications like portrait photography.)