A&P Problem with my lens? - pics

Discussion in 'Lifestyle' started by spahndirge, Aug 19, 2008.

  1. spahndirge

    spahndirge Scumbag Member

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    I got a 70-200mm f4 (non IS) on the advice of OT and I've been playing around with it and I think there may be a problem with it, although I'm just not sure (newbie!). There seems to be some blurring at certain points in the lens. I've 3 photos all at different apertures and the blurring isn't as visible with a smaller aperture, but it is noticeable.

    The pics were taken on a tripod at 200mm, I'm using a 40D. These are just test shots, I'm not stalking the neighbours :cool:

    Shot 1: F4
    Shot 2: F9
    Shot 3: F18

    If you look at the concrete wall on the right, the part beside the window is blurred a little, then it returns sharp as you move right and then gets blurry as you move to the drainpipe. There are a few areas where ghosting is at f4 (drainpipe, cut outs in the windowblind), but is this from being wide open?

    Any advice is appreciated.
     
    Last edited: Aug 19, 2008
  2. Bloke

    Bloke Banned

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    i think your f9 and f18 should look better. you need to keep in mind the depth of feild at 200mm is quite small, but not enough to account for that.
     
  3. spahndirge

    spahndirge Scumbag Member

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    The thing that worries me most is that the blurriness appears in waves, I have to get some better example shots tomorrow and see if it still occurs.
     
  4. Jonny Chimpo

    Jonny Chimpo OT Supporter

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    Normally, I would say that it's operator error, but in this case, I'd say your lens is actually borked.

    It appears that one of the elements is out of alignment which would cause that uneven out of focus area. I had a similar problem with my 70-200 f/2.8 after getting it serviced, where an element wasn't centered and half the image was out of focus.
     
  5. Bloke

    Bloke Banned

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    is it under warranty? id like to know how well canon takes care of this
     
  6. spahndirge

    spahndirge Scumbag Member

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    After trying out a line test to try and pinpoint what the problem is, it looks like it's only being affected at 200mm. I took these pics and it shows it pretty well...

    Shot 1: F4
    Shot 2: F9
    Shot 3: F18

    The main concern is that the top right hand corner seems to be the most heavily affected. I tried the same again at 70mm and there is no apparent problem....

    Shot 1: F4
    Shot 2: F9
    Shot 3: F18



    It still is under warranty, although there's only one store in Ireland that deals with canon warranty, and it costs about $200 just to be sent to canon to look at it without even repairing :(

    Is it worth the effort or am I being way too picky?
     
  7. Jonny Chimpo

    Jonny Chimpo OT Supporter

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    Too picky? Hell No. :ugh:

    I'd consider that lens to be seriously defective and requiring service or replacement.
     
  8. ace3

    ace3 mouthify my wang.

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    is there a standard "lens test" out there somewhere?

    i've seen the backfocus test (ruler at 45-degrees), and i think all of my lenses (at least at that time) are okay
     
  9. Jcolman

    Jcolman OT Supporter

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    There are several lens test charts available on POTN and Fred Miranda. Do a search and you'll turn up some. It's a good idea to test all your lenses under VERY controlled conditions. Make sure your lighting is flat and even, use a tripod, lock up the mirror and shoot away.
     
  10. Killyin

    Killyin Vicariously I, live while the whole world dies.

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    My 70-200 F/4 L is incredibly sharp even wide open.

    Looks like yours might have problems. :hs:
     
  11. spahndirge

    spahndirge Scumbag Member

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    Shite on it anyway, tested it out tonight and found the same result again, doesn't happen at 70mm or 200mm @ f18. Made up my own lens test page tonight.

    Here's the results....

    F4
    F9
    F18

    There's a huge difference between f18 and f9.

    I'm heading to New York next week and going to bronx zoo, so it's either no shots or use a defective lens :(
     
  12. Bloke

    Bloke Banned

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    rent a lens while on vacation
     
  13. spahndirge

    spahndirge Scumbag Member

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    Thanks a million :wavey:, I never even thought of that. I was planning on bringing the 70-200 over with me, I don't think i'll have any use for it other than the zoo. I was looking at adorama.com and saw the 70-200mm 2.8 IS there :wiggle:

    The only thing I'm concerned about is; will they rent to a tourist?

    What's the process of renting a lens?
     
  14. Killyin

    Killyin Vicariously I, live while the whole world dies.

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    It's usually something along the lines of:

    Have lens in stock? Yes/No

    Do you have a credit card? Yes/No
     

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