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Archive 2013 · lens calibration is no joke

  
 
Gochugogi
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p.2 #1 · p.2 #1 · lens calibration is no joke


abqnmusa wrote:
Sigma has the right idea with the USB dock so you can adjust your own lens.


I don't think that USB dock will do anything beyond calibration. Decentering and other similar adjustments require disassembly and hands-on mechanical tweaks. My 70-200 4L was blurry on the left side and no amount of calibration changed that. Canon service fixed it.



May 22, 2013 at 05:25 PM
nle57
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p.2 #2 · p.2 #2 · lens calibration is no joke


I agree. A few years back, when I dropped a 70-200, and it snapped some plastic, it cost, 250. If they need to just look at it to see if it is ok, the cost will also be 250 as well. In this case, my suspicions were indeed founded. They said the mechanical chasis was loose, and caused inaccurate focus, so they replaced it. And after the drop, I did quick tests in the field and found that it was fine. However, during actual post processing, I noticed the edges of all the images I shot with the lens was really really off. So I think I will just bite the bullet, and bring the rest of the lenses in as well. I wish there was a lighter inspection fee, and raise it up if things need fixing. Oh well. Cost of doing business =)

corndog wrote:
It's no different than annual trips to the doctor/dentist, or dropping the car off for inspection before a long trip. It's a CLA, a checkup, regular inspection after use, etc. People have been doing this with their camera gear for decades, there's nothing fishy about it. In the off-season, you drop your gear off to get it checked out in hopes that it prevents any issues during the time when you really need it. They didn't know he dropped one and for all we know it rolled off a gear bag onto shag carpeting in some motel. There should be
...Show more



May 22, 2013 at 05:59 PM
jcolwell
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p.2 #3 · p.2 #3 · lens calibration is no joke


nle57 wrote:
...So I think I will just bite the bullet, and bring the rest of the lenses in as well. I wish there was a lighter inspection fee, and raise it up if things need fixing. Oh well. Cost of doing business =)


I agree, it's part of the cost of doing business. OTOH, if it ain't broke, I don't send it in to get fixed.



May 22, 2013 at 06:12 PM
Andrew J
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p.2 #4 · p.2 #4 · lens calibration is no joke


Imagemaster wrote:
MA is not the same as calibration.

Canon believes it is or pretends to believe it is. I have met half a dozen people that have been told by Canon techs to use MA instead of mailing in gear that is out more than 15 points. I have similar/worse reports from Nikon users.



May 22, 2013 at 06:12 PM
jcolwell
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p.2 #5 · p.2 #5 · lens calibration is no joke


Andrew J wrote:
The difference now is Canon put MA in the bodies to avoid just this type of busy work. No exact descriptions of problems didn't help.

Imagemaster wrote:
MA is not the same as calibration.

Andrew J wrote:
Canon believes it is or pretends to believe it is. I have met half a dozen people that have been told by Canon techs to use MA instead of mailing in gear that is out more than 15 points. I have similar/worse reports from Nikon users.


I figure the Canon techs recommend using AFMA instead of sending it in, because in many cases AFMA will fix it. IOW, "the problem" is often not a situation where calibration and subsequent adjustment of the lens are required. If the user tries AFMA and it doesn't solve the problem, then it should be sent in.

I think this is an example of Canon techs trying to save the customer some money and inconvenience.

I think the Canon techs are on my side, at least in Canada they are.



May 22, 2013 at 06:21 PM
RCicala
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p.2 #6 · p.2 #6 · lens calibration is no joke


We have two entirely separate topics being discussed in this thread as though they are the same thing.

Autofocus calibration is adjusted by MFA or by electronic adjustment of the lens and/or camera at the factory. It's (relatively) simple and straightforward and makes the lens focus more accurately. It can't make it sharper or fix decentered optics and no adjustment of the lens optics is required.

Optical calibration fixes lens elements that are tilted, decentered, or out of alignment. MFA and autofocus calibration has absolutely no effect on the lens' optics.

When you drop a lens, it is much more likely to affect optical calibration rather than autofocus calibration.



May 22, 2013 at 06:30 PM
Mescalamba
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p.2 #7 · p.2 #7 · lens calibration is no joke


corndog wrote:
Can you elaborate on this?


Sure, mirrorless lens dont need MA.

Due way AF works in mirrorless (well those without AF sensors), its focusing very similar way to how we focus by hand. When sensor sees its sharp, its sharp. It cant backfocus or frontfocus, cause camera doesnt know if its further away or closer to you, so it locks simply only when its sharp enough.

AF in dSLR knows if subject is further away or closer to you. Which is source of back/frontfocus cause camera "knows" distance .. only problem is that distance it knows might be different from one on which its focused.

Plus that all is reason why AF-C doesnt work well (or closer to "not-at-all") in mirrorless cameras.

Tho as far as damage goes, it will behave like any other lens. If it will be damaged, it will need repair. There is just slight chance, that it will work even with small damage to optical alignment of lens elements (but most likely not).



May 22, 2013 at 09:41 PM
corndog
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p.2 #8 · p.2 #8 · lens calibration is no joke


Nice, thank you. The only part I don't understand is the mirror's role in knowing distance, and why a mirrorless couldn't know the distance just the same. However, this would probably be an hour long conversation at a pub and is likely not in the OP's interest. I will do some Googling.


May 22, 2013 at 09:56 PM
Doctorbird
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p.2 #9 · p.2 #9 · lens calibration is no joke


I wonder how much of a jolt a lens can take without getting out of alignment.

Glass is quite heavy and any kind of impact could shift the elements about. I would think that lenses with IS have components that are more delicately suspended; these could be more easily be dislodged and hence lead to more serious manifestations of malfunction in the lens.

Db



May 23, 2013 at 03:16 PM
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