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Canon EF 70-300mm f/4-5.6 IS USM Review (II)
Some time ago I favorably reviewed the Canon EF 70-300/4-5.6 IS USM. You can find the full review at HERE Since then I've been using the lens and I'm still impressed with the performance even wide open at 300mm, which is where the earlier EF 75-300/4-5.6 IS SUM showed weakness. I thought I'd show a few examples of shots taken with the lens wide open at 300mm to show what I'm talking about. Possible Problems?However first let me address an issue which a few people have been talking about, namely the rumor that the EF 70-300/4-5.6IS USM shows somewhat different performance with the camera in portrait and landscape modes. The suggestion is that resolution is noticably lower in portrait mode, presumably due to some sort of shift in the optics, perhaps due to play in the barrel. Well, I have noticed no such problems in actual use, but I did do some more controlled tests to see if the effect could be detected. The shots below are 100% crops from the center images taken at ISO 400, 300mm at f5.6 and a shutter speed of 1/320s. The camera was tripod mounted and shots were taken with IS on and IS off and the camera in vertical and horizontal orientation.
There's really no difference between horizontal and vertical shots, or between IS on and IS off. If you look close enough you may see some small differences (in fact these vertical shots seem perhaps very slightly sharper), but each shot was shot using autofocus and there can alway be small differences in focus. These are just 4 samples out of a larger set and looking at the larger set there's no consistent difference based on IS state or camera orientation. So all I can say is that my lens (which was one of the earliest lenses since I ordered it the day it was announced!) seems just fine. I have no complaints and in 6 months of actual use I've seen no evidence of performance changing with orientation. When shooting handheld I just leave the IS on. UPDATE - May 24th 2006 - Canon have issued a sevice notice concerning this issue. They acknowledge that there may be a problem with some lenses showing reduced edge resolution at 300mm in portrait mode and have stated that they are working on a method to resolve the issue. They say that they will make an annoucement by the end of June concerning approprite remedies. I don't know how many lenses show this effect and whether they all show it to the same extent. All I can say is that in practical use I have not noticed this effect and that on my LensPlay website, the average user rating on this lens is currently 8.5/10, a very good rating, so clearly it's not bothering too many users. I will take another, closer, look at my lens, looking more closely at the top and bottom of the frame at 300mm in portrait orrientation on images of a flat target and I'll report the results here.
Sample ImagesIn each case the shot was taken at 300mm and f5.6. The smaller image is a 100% crop from the full sized main image. If you're using a 17" monitor with a 1024 x 768 display, this represents a crop from a full size image which would be around 36" x 24".
Overall I'm very impressed with the EF 70-300/4-5.6 IS USM. Besides being pretty sharp, the IS is also very effective. For example the final image above (the turkey) was shot handheld at 1/100s. Without IS, to get an image of similar shapness you'd either need to be handholding a 6lb 300/2.8 lens or you'd need to be shooting at at least ISO 1600. These days I don't leave home without my EF 70-300/4-5.6 IS USM!
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