Lens Repair

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I bought a lens 2nd hand off ebay (which I will not do again :bang:), and have found that it is quite sharp in the centre only but fuzzy around the remainder although the focus distance is the same.

Is this fixable and worth taking to get repaired? If so, does anyone know the average cost to get something like this repaired?
 
It is a Canon 15-85 IS. I bought it a few weeks ago, but hadn't played with it until this last week, so may have left it too long :( but I have just sent a message in the hope...
 
I have a photo I can post, but is there any way of posting it direct on here without having to go via Flickr?

Aah, I have seen that I can post on Flickr but not for general viewing, so hopefully you will be able to see this.


Focus problems by nzweeble, on Flickr

Please take no notice to the composition!
 
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Ha ha, it is Dom. He was at our local animal sanctuary yesterday filming.
 
Yea lens look ok to me to if not what am I missing... ?
 
Alot of lenses go soft when you move out from centre, canons DPP can correct some of it but its just one of those things, I cant see a larger version of the pic so cant say but the small pic looks fine. You will also get barrel/ pin cushion distortion etc
 
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15-85 is a very good lens. Unless there is some obvious sign of damage, eg lens has been dropped, then the chances are it's fine.

Use it some more. Check sharpness across the frame by shooting a distant subject, which will minimise potential focusing and other errors.

Edit: as mentioned above, Canon's DPP software has a custom lens aberrations correction suite, which works really well. Just a mouse click to fix CA, vignetting and distortion - which is probably not what you're talking about here, but will make an already good image even better.

You need to shoot Raw though, and the copy of DPP you have a with a 450D will need updating for that lens. The upgrade is free. See what DPP does here - toggle on the images half way down the page http://www.dpreview.com/lensreviews/canon_17-85_4-5p6_is_usm_c16/page3.asp
 
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Oh, thanks. It is along his arm, from the elbow to the hands it becomes very fuzzy, and really not good - so is this normal? Sorry I didn't realise you couldn't see the larger version.

When I bought it, I was made aware that it had been dropped a little, but was advised that it was in perfect focus. Is it still worth sending off to get this looked at?
 
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Well I can't see any obvious problem. And even if there is, could be several causes.

If you think there's comething wrong, or just to reassure yourself, then take some pictures. As I said above, something with a bit of distance to minimise focusing errors, and also something static to eliminate movement blurring.

What does the fence look like in the background? What were your camera settings - focal length, aperture and shutter speed?
 
why does that fence look distinctly weird , or is it just me :thinking:
 
I have tried a larger format


Focus problems by nzweeble, on Flickr

at
Camera Canon EOS 450D
Exposure 0.002 sec (1/640)
Aperture f/5.0
Focal Length 15 mm
ISO 200

The fence was going around a corner to the right of the photo, so I think it is ok.

I am going to print off a picture of the Union Jack tomorrow and take some static pictures as suggested (also with my 50 prime to see the differences) so hopefully this will show the sharp lines, and also as suggested I will try some with distance.

Looking at this more, I see that it could look like his hands are moving, but I also have this picture which seems to have the same distortion - look at his scarf which is sharper on the left side than the right, and his arm is fuzzy (same settings)


Dom2 by nzweeble, on Flickr
 
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Sorry, last example...

Shouldn't their showes be in focus as they are the same focal distance? Really appreciate your comments and help.


Dom1 by nzweeble, on Flickr
 
Doesn't look right to me, the bottom middle to left cetainly looks soft. I have the same lens and haven't noticed anything similar, although I haven't used it much and when I do it's with the 7D which has automatic correction software for it.

Off to try and find some images...
 
I actually had a problem with my first 15-85 IS USM when I shot Canon. My problem, and possibly yours too, is one of decentering. The left hand of my images was consistently soft compared to the right.

Here's what I recommend you do to test it; take a test shot of a subject with plenty of depth of field and interest around the edges of the frame, say at around f/8-11, then [and this a little fiddly] hold your camera upside down and take the same shot. Now in whatever software you choose [DPP is good], rotate the upside down shot to match the normal one. Compare the two images. If your lens is afflicted by decentering, any soft area will appear to switch sides between the two.

Then you have a choice to return the lens or have it serviced. Let us know how you get on.
 
I don't have anything similar to compare it with unfortunately, I have a few shots that are at 15mm but At f8 and they're landscapes and look pretty sharp over the frame as you'd expect. Shooting people at 15mm, it's not something I'd do really unless it's a very large group and I'd be miles away lol.
 
Those sample pics are very inconclusive, but it does look like there is room for suspicion around the left/bottom, possibly decentering - especially if the lens has indeed taken a knock.

Easy to test. First thing - does it feel okay? Are the zoom and focusing rings smooth? Then choose a fairly distant target like a car number plate or road/street sign, in decent light, and focus on it carefully using single centre-point AF. Switch focus to manual to lock it. Set exposure in manual, also to lock it, at lowest f/number, and make sure the shutter speed is high.

Take pictures with the target positioned in all four corners of the frame, then zoom in on the LCD and compare them (LCD on a 450D should be good enough for this). The target should look equally sharp in all four images.

Don't expect it to be very sharp because this is a tough test and it won't be. No lens is ever at its best in the corners. You are looking only for equality. Make sure the light doesn't change between shots, eg clouds blowing over, and be aware that sharpness falls off very rapidly in the corners so the target must always be exactly the same distance form the edge each time. With a number plate for example, look at the letters in the middle, not at the ends, because one end will always be closer to the edge and therefore likely to be more blurred anyway. Consistent and careful positioning of the target is essential, so a tripod might help.

If you have to look twice, there isn't a problem. If there is any decentering to worry about, it will be obvious. If all four look pretty equal, test at different focal lengths and focusing distances - it's possible that it's the mechanism that has been knocked out of alignment and it will only show up at certain settings, eg the ones used above. Don't go too close though, or even slight focusing errors could creep in.
 
I have the same lens and haven't had problems with it, although I wouldn't say it's the sharpest thing available.

If you already know that it has been dropped then you could have it looked at by someone like Fixation if you're worried about it. Otherwise you're going to spend all your time looking for faults in your photos, which would be a shame!

S
 
Thanks so much for all your advice, and I have completed the tasks. Although it is not bad, I can see the soft spots in certain areas (mainly on the left).

But as suggested, I am going to send it off for testing and repair, if not only for peace of mind, otherwise I would always be looking for fault.

I will let you know how I get on. I have heard Fixation is good?
 
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