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Thread: How to Test a Lens Sharpness

  1. #1

    Default How to Test a Lens Sharpness

    Hi,

    Intend to buy a Tamron 28-75 F2.8 but was told that there are many unsharp copies.

    Wanna know how to test whether a copy is sharp or not? I intend to bring my camera body down to test the lens.....BTW buying brand new one from shop......

    Thank you,

  2. #2

    Default Re: How to Test a Lens Sharpness

    i also want to know.

    Btw you buying the latest model? Feel like buying one.
    But duno to get 28-75 or 17-50.
    Also duno which brand better (amongst sigma, tamron & tokina).
    Last edited by sin77; 4th January 2009 at 11:18 AM.
    D7100,SB910,17-50/2.8OS,105/2.8VR,85/1.8D,2xE-M1,O60/2.8,12-40/2.8,35-100/2.8,14-42,LX100

  3. #3
    Senior Member Anson's Avatar
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    Default Re: How to Test a Lens Sharpness

    Curious... how do you define lens sharpness... coz a lens in different camera have different level of sharpness too...

  4. #4

    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by Anson View Post
    Curious... how do you define lens sharpness... coz a lens in different camera have different level of sharpness too...
    tamron is known to have sharp and soft copies of the same model lens, i.e. inconsistent.

    As for sharpness... very hard to describe... most lenses if you open to widest e.g. f1.8, the image might become softer as compared to f2.8 and beyond. And no, i am not referring to bokeh effect or handshake problem.

    Its like a myopia...
    D7100,SB910,17-50/2.8OS,105/2.8VR,85/1.8D,2xE-M1,O60/2.8,12-40/2.8,35-100/2.8,14-42,LX100

  5. #5
    Moderator Octarine's Avatar
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    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by Saabo King View Post
    Intend to buy a Tamron 28-75 F2.8 but was told that there are many unsharp copies.
    Wanna know how to test whether a copy is sharp or not? I intend to bring my camera body down to test the lens.....BTW buying brand new one from shop......
    That means you are testing at home? Get a Focus Test Chart like this and setup according the guidelines. Should give you pretty good results about the focus of the lens. In case you get errors please also test with other lenses to make sure whether the cause is the lens or the body.

  6. #6

    Default Re: How to Test a Lens Sharpness

    No Testing in the shop

  7. #7
    Moderator Octarine's Avatar
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    Default Re: How to Test a Lens Sharpness

    You can still use the test chart. Alternatively you can use AA batteries or anything similar where you can test the focusing on single objects. Make sure it has a good contrast to background (e.g. IKEA batteries could be better than Duracell.) Lay down the batteries with 2..3 cm distance and shoot from 45 degree angle like using focus charts.
    Alternatively: put them standing in a row with 2..3 cm distance, shoot from 45 degree angle sideways at same level.
    The basics are the same: test at minimum focusing distance, use single focus point, have proper light. Be careful about background elements that could distract the focus (e.g. things under the glass plate). Do several shoots. The camera might not always lock the focus instantly at the right point and you can mistake it for focusing error.
    Best if you take a laptop with you to see the pictures at full magnification on screen.

  8. #8

    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by Saabo King View Post
    No Testing in the shop
    another shop then.
    You wont see me much less remember me but i am the guy who makes you look good.

  9. #9

    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by Reportage View Post
    another shop then.
    I think he meant "no, testing in the shop"

    The difference a missing comma makes...
    Nikon D60 | Tamron 17-50mm f/2.8 | Nikkor 18-55mm | Nikon 55-200mm VR | Nikon SB-400

  10. #10

    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by Saabo King View Post
    No Testing in the shop
    Hey saabo king (i like yr nick, but u'll have problems selling yr lens later wif this nick).

    These are relatively cheap lens, so if the shop owner dun allow testing, as our fellow bro said, go buy from another shop. Unless of course u're asking to test a 10k lens, which the owner might have some reservations...

  11. #11
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    Default Re: How to Test a Lens Sharpness

    is this sharp to you?

    used to own both the 2875 tamron and the 1750 tamron. still using the 1750 tamron

  12. #12

    Default Re: How to Test a Lens Sharpness

    a bit soft... i guess it is not due to black and white.
    D7100,SB910,17-50/2.8OS,105/2.8VR,85/1.8D,2xE-M1,O60/2.8,12-40/2.8,35-100/2.8,14-42,LX100

  13. #13
    Senior Member Anson's Avatar
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    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by sin77 View Post
    tamron is known to have sharp and soft copies of the same model lens, i.e. inconsistent.
    No QC?

  14. #14
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    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by sin77 View Post
    a bit soft... i guess it is not due to black and white.
    LOL it was done with my LX-1. anway the tamron is sharp even wide open

  15. #15

    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by jtchoy View Post
    I think he meant "no, testing in the shop"

    The difference a missing comma makes...
    Ah.....that is why the "No" and "Testing" are in capital........it denotes a new line....

    My form of grammar....

  16. #16

    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by Saabo King View Post
    Ah.....that is why the "No" and "Testing" are in capital........it denotes a new line....

    My form of grammar....
    English as it is broken.

    Bring down a focus test chart, or use the batteries method. If you're not a pixel peeper and sharpness is not an insanely important issue with you, you can just shoot a newspaper with small print instead.

    Quote Originally Posted by Anson View Post
    No QC?
    Even with QC, I'd say its hard to control the quality of something like that. They can't exactly manually test EVERY lens they produce, I'm guessing, without any research, that they do random batch sampling for QC.
    It is such a quiet thing to fall,
    But far more terrible is to admit it

  17. #17

    Default Re: How to Test a Lens Sharpness

    remember, you have to get the focusing right first. For wide aperture lens, most of the issue wide open is due to SLIGHT misfocus.

  18. #18

    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by vonlichenstein View Post
    English as it is broken.
    Even with QC, I'd say its hard to control the quality of something like that. They can't exactly manually test EVERY lens they produce, I'm guessing, without any research, that they do random batch sampling for QC.
    They should pre-calibrate every lens nevertheless. Sure they can't QC every single one, but the hit and miss rate is a little too high, especially with Sigma's longer lenses. I think its basic service anyway, we don't see Canon or Nikon lenses having as much problems... although I sent in 2 lenses for recalibration and they did nothing to help my focusing issue. -.-
    Last edited by ombre; 5th January 2009 at 12:27 PM.
    Looking for Canon 100mm F2 USM :)

  19. #19

    Default Re: How to Test a Lens Sharpness

    Anyway, I feel that this topic is very off track. Title says lens sharpness but more than half of the posts talk about focusing errors? Even a properly focused picture may be soft due to lens quality, although yes, an off focus pic is definitely soft.

    Anyway, after being a pixel peeper for so long, I still must say lens sharpness is subjective, and unless you're a mega size printer, or always cropping due to lack of range on your lens, you probably don't really need perfect sharpness.

    Also depends if you're talking about center or corner sharpness... whats the definition of sharp in this conversation here?


    To TS, which range do you need more really? 28-75 naturally suffers a little at the corners wide open, although multiple reviews claim that the center is comparable to 24-70L. 17-50 known to be sharp wide open, but if you ask me, this applies to 17-35 better, the 50mm F2.8 part suffers a little... but really, it depends on how you use it.

    If you're comparing between these 2, just choose the range you need. As for how to test for sharpness... you can just shoot flat against a newspaper, the 45 degrees thing is just for focusing. When shooting flat, pixel peep the center/ corners, every part... Don't have unrealistic expectations about the corners though.

    Just my 2 cents, everyone has their own way of doing it. You can also design your own test chart and bring it there.


    (psst, btw if you know the price for 28-75, please pm me thanks ^^)
    Looking for Canon 100mm F2 USM :)

  20. #20

    Default Re: How to Test a Lens Sharpness

    Quote Originally Posted by ombre View Post
    Anyway, I feel that this topic is very off track. Title says lens sharpness but more than half of the posts talk about focusing errors? Even a properly focused picture may be soft due to lens quality, although yes, an off focus pic is definitely soft.

    Anyway, after being a pixel peeper for so long, I still must say lens sharpness is subjective, and unless you're a mega size printer, or always cropping due to lack of range on your lens, you probably don't really need perfect sharpness.

    Also depends if you're talking about center or corner sharpness... whats the definition of sharp in this conversation here?


    To TS, which range do you need more really? 28-75 naturally suffers a little at the corners wide open, although multiple reviews claim that the center is comparable to 24-70L. 17-50 known to be sharp wide open, but if you ask me, this applies to 17-35 better, the 50mm F2.8 part suffers a little... but really, it depends on how you use it.

    If you're comparing between these 2, just choose the range you need. As for how to test for sharpness... you can just shoot flat against a newspaper, the 45 degrees thing is just for focusing. When shooting flat, pixel peep the center/ corners, every part... Don't have unrealistic expectations about the corners though.

    Just my 2 cents, everyone has their own way of doing it. You can also design your own test chart and bring it there.


    (psst, btw if you know the price for 28-75, please pm me thanks ^^)
    Bravo!!! I finally got an idea of what I can do in the shop without doing funny things like shooting Ikea batteries etc........

    Thank you all anyway for the contributions. I will post the price of the lens and whether my purchase is successful.

    Cheers!

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