How to find out if lens is too soft/bad copy ???

Discussion in 'Photography Beginners' Forum' started by YoungRebel, Apr 13, 2008.

  1. YoungRebel

    YoungRebel TPF Noob!

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    I tested the lens with the chart:
    It a little weird 'cause depending on the focal-length I set it, it has either a little back- or front-focussing problems.

    Not too extreme, but sometimes the text that's supposed to be in focus is almost out of it...

    It also varies at different f-stops...


     
  2. soylentgreen

    soylentgreen TPF Noob!

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    At what ranges? The lens should be sharpest around the 50-55mm range. Try at diffrent ranges wide-open 24,50 & 70 f/2.8. Post some pics if you got them handy. Rarely there may be a problem.
     
  3. K8-90

    K8-90 TPF Noob!

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    Going to resurrect this post :p

    I'm in the same situation, just ordered the Canon 24-70mm 2.8 lens. Should I test it once I get it? Is that common practice? I decided not to purchase the extended warranty, so I want to make sure it's a good copy asap.
     
  4. KmH

    KmH In memoriam Supporting Member

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    You should have just started your own thread.

    Most people make some photos when a new lens they have just purchased arrives.

    That is one way to test it.

    The warranty is good for at least a year, if the lens is new.

    Extended warranties are usually not a good buy.
     
  5. Village Idiot

    Village Idiot No longer a newbie, moving up!

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    I had to adjust my 24-70 almost all the way out to +20 because it's focus was off. That definitely helped with sharp photos.
     
  6. Village Idiot

    Village Idiot No longer a newbie, moving up!

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    I know. I ****ing rock.
     
  7. K8-90

    K8-90 TPF Noob!

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    LOL. I can never win! If I had started a new thread, I would have been told to use the search feature :er:

    Thanks for the help, though. I'll obviously be taking some photos once I get it, but there are so many variables in what makes a lens soft! I thought there might be some method used to test them. Guess I'll try that focus chart mentioned in the initial posts.

    ...I'd also like to know what Village Idiot meant by the adjusting +20...
     
  8. Village Idiot

    Village Idiot No longer a newbie, moving up!

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    I know Canon has started including features with their newer cameras called micro adjust which lets you change the focusing range of your lenses +20 or -20 steps from it's stock setting. This way, you can adjust a lens that's front focusing or back focusing. I believe they started this with the 5D MKII.

    Other manufactures may or may not include an option like this in their cameras. RTFM.
     
  9. K8-90

    K8-90 TPF Noob!

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    Huh, cool. Will have to look into it...

    PICKING LENS UP TODAY :D
     
  10. pgriz

    pgriz Been spending a lot of time on here!

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    It's never a bad idea to "calibrate" your gear. Front-focus and back-focus issues are pretty easy to test. Knowing your resolution (center and corners) at various f/stops for each of your lenses is also a good idea. You don't even need a lens resolution chart (although it certainly helps) - a target with detail ranging from coarse to very fine will do. The point is that each of us should take the time to work with our gear in a controlled and structured way to know what it can do.
     
  11. RacePhoto

    RacePhoto TPF Noob!

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    Yes it's been a couple of months, but I couldn't find the thread asking about getting a "good copy" of the 100-400MM Canon zoom, this is the best one the search turned up.

    Interesting viewpoint.

    https://www.lensrentals.com/blog/2008/12/this-lens-is-soft-and-other-myths

    Cameras vary, lenses vary if you get a camera that's -2 and a lens that's -2 you are going to see some focusing issues. And if you keep changing lenses until you get a nice set that matches your camera, and the camera is way to one direction, they may not match your next camera!

    Thank you camera makers for adding micro adjustments.
     

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