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Lens calibration - dangerous ground or routine procedure?

Discussion in 'Pentax Chat' started by John_Hine, Mar 11, 2011.

  1. John_Hine

    John_Hine Well-Known Member

    Being new to Pentax, the owner of a 3-month-old K-r, I am new also to the idea of D-I-Y lens calibration. The K-r's manual warns that "AF fine adjustment" - presumably synonymous with calibration - should be attempted only if absolutely necessary and seems to suggest that success is not guaranteed. However, in various forum threads, both here and elsewhere, contributors refer to such adjustment as if it is no big deal. I realise that my rather inconsistent early results from the K-r almost certainly tell me more about myself than about camera or lens but, if I should become convinced that some adjustment is needed, with how much trepidation should I proceed?
     
  2. johnriley1uk

    johnriley1uk Well-Known Member

    I would suggest you get to know your camera first. I have never yet found a lens that didn't focus where I pointed it, but some people seem to report that almost all their lenses need adjustment.

    Be sure before you start fiddling - there are plenty of images to shoot and you'll soon know if there's a probelem if you practice enough.
     
  3. GDN

    GDN Well-Known Member

    My lens have been fine on my K10D, K20D and K7, however on my K5 I have had to adjust one by -8 and another by -2. I have only performed it on my fixed lens, not my zoom lens.

    Its quite a simple process and easily resetable to the original settings. The key to the calibration is having accurate adjustment charts. If you've printed a chart, cut it out and bent it can you be 100% certain you are at 45 degrees and the optimum distance away? Thats why there are purpose made calibration tools you can buy. Yes they are expensive but they show any focus issues extremely well allowing specific calibration to occur.

    One thing also to remember is that its going to be the faster lens (f1.4-f2.8) where your DOF is narrower that you'll more likely to notice a focus error, with the kit lens the DOF is larger and therefore less prone to be noticed. ;)
     
  4. John_Hine

    John_Hine Well-Known Member

    Many thanks, gentlemen. Yes, after a bit more practice I am beginning to notice an improvement in the sharp focus hit rate - at shorter focussing distances, curiously enough, as you might expect longer distances to give more DOF and look better. After many years of Canon, I think I need a running-in period with Pentax. I shall not hasten to blame the equipment.
     
  5. Done_rundleCams

    Done_rundleCams AP Forum Ambassador to Canada

    :D :D :D :D

    Ah good John, then I won't be the only one :rolleyes:

    I just picked a K-r this past December.

    Cheers and welcome to the K-r ...err ... Pentax forum :)

    Jack

    :)
     
  6. Monobod

    Monobod Phantom of the forum

    Is this ability to correct in this way unique to Pentax?
     
  7. johnriley1uk

    johnriley1uk Well-Known Member

    I think the facility is now included in the higher end cameras of other marques, principally Nikon.
     
  8. LargeFormat

    LargeFormat Well-Known Member

    Certainly there with Sony.

    Which I guess is what John means. :D
     
  9. Benchista

    Benchista Which Tyler

    Canon have had it for quite some time.

    The danger comes from applying an incorrect or unnecessary correction. IMHO it shouldn't be set just before an important shoot, nor without sufficient testing to ensure that the result really is better than before.
     
  10. El_Sid

    El_Sid Well-Known Member

    It's available on most top end Canons (50D and above)...
     
  11. RogerMac

    RogerMac Well-Known Member

    It is present on the Oly E5 and has been on the E30 for some time, but not on the E3 and there was some criticism of a batch of early E3s that were misaligned and had to be returned under warranty when a calibration option would have sorted it out. Of course one advantage of the contrast detect systems used on most CSCs (perhaps the only advantage) is that they are immune to this type of problem.

    Edit: I believe that there are some Sigma lenses that consistently front focus and really do need this facility

    Roger
     
  12. John_Hine

    John_Hine Well-Known Member

    Having sought your advice about this calibration business I thought I should report on progress. I finally became convinced that some adjustment was needed, overcame my fear and did the deed. I printed out a calibration chart and found that the 16-45 lens focussed properly at minus 5 on the AF adjustment scale. Images taken since adjustment have been much better. Adjustment is a simple and reversible process so I cannot understand why the K-r manual makes it sound hazardous.
     

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