Lens Calibration Question

Discussion in 'Canon EOS' started by zacman, Jan 11, 2010.

  1. I hope I am posting this in the right forum. It concerns A Canon body and a non Canon lensl.
    I currently shoot with a Sigma 17-70mm lens on a Canon XTi body. I have benn less than 100% happy with the Sigma lens since I got it. It seem to produce out of focus photos - at times - mostly at distance (infinity). I recently contacted Sigma Corp. Customer service responded rather quickly, twice. The first response was from a customer service rep who stated that it could cost up to $100.00 to calibrate. I then made the decision that I just would not buy another Sigma lens,, and stick with Canon lens.
    A day later I get an E-mail from a different Sigma customer service rep that says they will calibrate it for free,, but I have to send them my Canon body and the Sigme lens. I am quite hesitant to do this, and at this point I feel that I will revert back to my - not buying Sigma products any more. I have heard many times of folks getting their lens calibrated, or re-calibrated,, but does the camera body have to be shipped with it in order for the lens to be adjusted? Any insight would be greatly appreciated.
     
  2. I understand that Canon do not calibrate the lens on the camera, but then again they have their owninternal standards so maybe they don't need to (if lens and camera independently meet these standards then they should work together).
    Maybe Sigma go one step further and calibrate the lens through their normal processes and do a final check using shots taken with the camera? I twould be interesting to find out. If you get inconclusive replies you could always as the customer services people (though you seem to have had variable experience with them so far).
     
  3. double post
     
  4. Before you do any kind of repair or calibration, you need to verify that you really have a problem. How have you tested the "sharpness" of the lens/camera combination? Have you tried manual focus on controlled distances? Any other kind of tests? Or are you just unhappy looking at 100% blowups on the screen of your computer?
    If the latter, it is unlikely that going to Canon or any other lens is going to solve the problem.
     
  5. That is why I(canon snob) stay away from cheap third party lenses. As far as I know, last time I sent my ef 50L to canon for calibrations, the second time they requested to send my camera body as well to calibrate both together. I don't know how they do it, but somehow they used the camera to calibrate my lens.
     
  6. Try lens align kit, should do the job.
     
  7. Yes, Canon do calibrate Canon lenses w/ camera body. I saw that twice at the Irvine facility. The thing is the calebration they do must be w/ a lens and a body. The process is very expensive. Furthermore, I heard, once a body has been calibrated w/ a lens, it has to be re-calibrated w/ another lens. You may want to find out more about this.
     
  8. I heard, once a body has been calibrated w/ a lens, it has to be re-calibrated w/ another lens.​
    This would be a nonsensical arrangement, and I hope and believe that it is not true. My understanding is that both cameras and lenses are calibrated to a common standard, and the reason that Canon seek to calibrate both together is that they do not want complaints about a lens still being incorrect after calibration when the problem lies with the body.
    In my view professional and prosumer bodies and lenses should be individually calibrated as part of the manufacturing process. Yes, it would add something to the cost, but there's no reason why it should be a large addition, and it would certainly be cheaper than having it done by the user.
     
  9. Robin said: In my view professional and prosumer bodies and lenses should be individually calibrated as part of the manufacturing process. Yes, it would add something to the cost, but there's no reason why it should be a large addition, and it would certainly be cheaper than having it done by the user.
    Calibration is already part of the manufacturing process, but the "tolerance" factor is where the issue resides and as one might expect, tighter tolerances and exactness mean added costs - think Hasselblad, superbly exacting... but oh my, the cost of an Hasselblad camera, or lens.
    And though a vast majority of camera users wouldn't admit it, so-called "camera issues" are far more often related to the person holding the camera, infamous "user error" at camera-level and in post-processing on the computer. Advertising hype also wiggles its way into this equation, too, which results in dream-like customer expectations... push the button and a "perfect" image results! No skill required.

    Yes, a camera body can be calibrated - without - a lens; likewise a lens can be calibrated without the body; it's normally done that way. Calibration in either case is the correction from the mounting surface to whatever is "the standard."Calibrating a camera body+lens is more involved, more expensive to undertake (it adds a third layer to the calibration process: lens by itself; camera by itself, then the two together for "ultimate" perfection... which in truth means simply a tighter tolerance - but still not absolutely perfect. You are correct about questioning the validity of the statement suggesting "I heard , once a body has been..." The classic rumor-mill in action.
     
  10. To do the best job, any service tech needs the lens and a body. For example, assume that manufacturing (lens and body tolerances) may be +-2 units from perfect. If both lens and body happen to be 0 or +1 and -1 then all is good. However, if both happened to be +2 then you're probably going to experience some focus issues. Thus, the Sigma tech could calibrate your lens to the theoretical zero point, but if your body is off than their work may be for naught. In fact, it may even make things a bit worse. Canon works the same way.
     
  11. However, if both happened to be +2 then you're probably going to experience some focus issues.​
    Actually, if both are +2 units "off", this would probably be your favorite lens. The problem arises when your body is -2 and your lens is +2. This is also the reason for calibrating both your body and your lens(es) together.
     
  12. Avery - I don't think it is necessary to calibrate both together.
    QC standards are there so that a company can sell a 'non-perfect' item that still does a very good job. Your camera may not focus perfectly, but does it matter if it is 1mm out? 5mm out? 100mm out? Each company defines its limit of acceptability and that is its QC limit. On he poduction line this limit prevents the high cost of making sure every item is absolutely and unnecessarily perfect.
    But once you send an item to be individually calibrated then in general it will often end up being tweaked to tighter tolerances than on the original production line and I guess this is why many people report a lens comes back much better after calibration. Equally if you send lens and body to be calibrated, then both may well come back closer to Canon's ideal so they will be better matched without any need to test them as a single unit.
    If you did both together you risk tweaking the body closer to the lens and in the process taking it further away from other lenses in your collection and that would not make sense.
     
  13. Interesting, related read...
    http://www.lensrentals.com/news/2008.12.22/this-lens-is-soft-and-other-myths
     

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