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Hi,
I'm looking for some help figuring out whether I need to have my Canon telephoto lens repaired. It's a 1st generation Canon 70-200mm F/4 L IS USM lens, purchased in Hong Kong in 2008. I've never been fond of it, because it's never yielded particularly crisp images. Because I've used it so rarely, I never really took the time to investigate properly. However, I used the lens extensively during some recent travel and it was only after I came home and saw the fairly horrible results, that I thought I really needed to make sure that what I was looking at was "normal". A couple of hours searching the web suggested to me that it was not.
The lens is hailed widely for its tack sharp images. My lens is anything but sharp. The chief problem is break down in sharpness towards the edge of the frame. This break down results in some obvious halos, but it's the blurring and lack of sharpness which has me most worried. The blur gets particularly bad towards the edges of the images, and even worse in the corners. However, it's also the NATURE of the blur that's worrying me. It looks to me more like a motion blur, with that slightly dizzying, disorientating, "vertigo" effect. This is an example (F8, 250/1, on full 200mm zoom with IS used). The lack of crispness of the three subjects is not the concern here; the real alarm is the look of the blur, particularly towards the corners. The branches and leaves look like they're being pulled and stretched, as if I have moved the camera while shooting.
IMG_20150430_7933 by grambers, on Flickr
Today I have tested the lens using two bodies (a Sony A7S body using a Metabones EF-E lens adapter; and a Canon 5D (Mark 1) body on which I have done most of my shooting). I mounted the camera(s) onto a tripod, used a remote shutter switch, maintained a relatively fast shutter, and switched OFF the Image Stabilizer (to remove this as being a potential cause of the problem). I then tested the lens at a variety of apertures and focal lengths by shooting a flat brick wall about 3 meters in front of me. Below is a screenshot of four images (shot with the Sony A7S) compared in some lightroom software. They were shot in succession with full zoom (200mm). From left to right, they were shot at: 1) F4 (400/1), 2) F5.6 (200/1), 3) F8 (160/1), 4) F16 (100/1), with the ISO on auto. To reiterate, all were shot on a tripod with a remote shutter switch. What is shown is the very top right corner of the image. As you can see, there's real softness and marked blurring, which improves considerably at smaller apertures. However, even at F16 there is (to my mind, at least) unacceptable blurring in the very top right of the image.
Toprightofframe200mm by grambers, on Flickr
For comparison, here are the centres of the same images compared. There's no blurring at all here, though it's notable how 'soft' the F4 image is (NOTE: these were shot on manual focus, and there was no change at all between shots, other than me playing around with aperture and shutter speed...focus remaining consistent).
centreofframe200mm by grambers, on Flickr
I understand that blurring will become more of an issue at longer focal lengths, so here's a comparison of the same wall shot at the widest focal length (70mm), this time looking at the bottom left of the image. Again, the blurring at the wider apertures (F4 and F5.6) is very noticeable...to reiterate, tripod, remote shutter, and fast shutters were all used, and IS was turned off.
Bottomleftofframe70mm by grambers, on Flickr
The last image captures the essence of the problem when the lens is used in the real world. That "motion-sickness" blur is noticeable throughout the foreground. However, the subject's shoes are in reasonably sharp focus. However, pan up to her head (clearly lying within the same focal plane) and there is huge blurring going on.
IMG_20150408_7061 by grambers, on Flickr
For clarity, though these shots were taken on a Sony body, the results were replicated when I tested the lens using my Canon 5D, so this is not a compatibility issue.
In short, I appear to have a lens where shots at f/4 are always overly soft, and where, though the centre of my images are often acceptably sharp, the blur at the edges of the frame (and especially in the corner) is sometimes extreme. I'm pretty sure I need to get my lens looked at, but before I spend my money I'd love a little reassurance from anyone who knows this particular lens, and who has more experience with lens problems than I. Do I have a problem, or is this just the "way it is" with telephoto lenses, even expensive Canon lenses? I find this hard to believe given Canon glass' reputation.
Thanks so much folks.
I'm looking for some help figuring out whether I need to have my Canon telephoto lens repaired. It's a 1st generation Canon 70-200mm F/4 L IS USM lens, purchased in Hong Kong in 2008. I've never been fond of it, because it's never yielded particularly crisp images. Because I've used it so rarely, I never really took the time to investigate properly. However, I used the lens extensively during some recent travel and it was only after I came home and saw the fairly horrible results, that I thought I really needed to make sure that what I was looking at was "normal". A couple of hours searching the web suggested to me that it was not.
The lens is hailed widely for its tack sharp images. My lens is anything but sharp. The chief problem is break down in sharpness towards the edge of the frame. This break down results in some obvious halos, but it's the blurring and lack of sharpness which has me most worried. The blur gets particularly bad towards the edges of the images, and even worse in the corners. However, it's also the NATURE of the blur that's worrying me. It looks to me more like a motion blur, with that slightly dizzying, disorientating, "vertigo" effect. This is an example (F8, 250/1, on full 200mm zoom with IS used). The lack of crispness of the three subjects is not the concern here; the real alarm is the look of the blur, particularly towards the corners. The branches and leaves look like they're being pulled and stretched, as if I have moved the camera while shooting.
IMG_20150430_7933 by grambers, on FlickrToday I have tested the lens using two bodies (a Sony A7S body using a Metabones EF-E lens adapter; and a Canon 5D (Mark 1) body on which I have done most of my shooting). I mounted the camera(s) onto a tripod, used a remote shutter switch, maintained a relatively fast shutter, and switched OFF the Image Stabilizer (to remove this as being a potential cause of the problem). I then tested the lens at a variety of apertures and focal lengths by shooting a flat brick wall about 3 meters in front of me. Below is a screenshot of four images (shot with the Sony A7S) compared in some lightroom software. They were shot in succession with full zoom (200mm). From left to right, they were shot at: 1) F4 (400/1), 2) F5.6 (200/1), 3) F8 (160/1), 4) F16 (100/1), with the ISO on auto. To reiterate, all were shot on a tripod with a remote shutter switch. What is shown is the very top right corner of the image. As you can see, there's real softness and marked blurring, which improves considerably at smaller apertures. However, even at F16 there is (to my mind, at least) unacceptable blurring in the very top right of the image.
Toprightofframe200mm by grambers, on FlickrFor comparison, here are the centres of the same images compared. There's no blurring at all here, though it's notable how 'soft' the F4 image is (NOTE: these were shot on manual focus, and there was no change at all between shots, other than me playing around with aperture and shutter speed...focus remaining consistent).
centreofframe200mm by grambers, on FlickrI understand that blurring will become more of an issue at longer focal lengths, so here's a comparison of the same wall shot at the widest focal length (70mm), this time looking at the bottom left of the image. Again, the blurring at the wider apertures (F4 and F5.6) is very noticeable...to reiterate, tripod, remote shutter, and fast shutters were all used, and IS was turned off.
Bottomleftofframe70mm by grambers, on FlickrThe last image captures the essence of the problem when the lens is used in the real world. That "motion-sickness" blur is noticeable throughout the foreground. However, the subject's shoes are in reasonably sharp focus. However, pan up to her head (clearly lying within the same focal plane) and there is huge blurring going on.
IMG_20150408_7061 by grambers, on FlickrFor clarity, though these shots were taken on a Sony body, the results were replicated when I tested the lens using my Canon 5D, so this is not a compatibility issue.
In short, I appear to have a lens where shots at f/4 are always overly soft, and where, though the centre of my images are often acceptably sharp, the blur at the edges of the frame (and especially in the corner) is sometimes extreme. I'm pretty sure I need to get my lens looked at, but before I spend my money I'd love a little reassurance from anyone who knows this particular lens, and who has more experience with lens problems than I. Do I have a problem, or is this just the "way it is" with telephoto lenses, even expensive Canon lenses? I find this hard to believe given Canon glass' reputation.
Thanks so much folks.
