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Archive 2014 · … A Few Canon Questions …

  
 
Jefferson
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p.1 #1 · p.1 #1 · … A Few Canon Questions …


… What did people do before MAs and why is it such a big deal now … ? Did Canon cut back on QC … ? Why do you now have to tune your recently purchased lens / body, to whatever you are going to shoot that day … ? Was photography and the equipment used before MA that bad that often Canon had to come up with a Do It Yourself QC Kit … ?

If my old 300 f/4L IS is sharp on my 5Dc, and sharp on my 1Ds2 … it should be sharp on a 1D IV and the new 7D II with very few exceptions … IMO

Some lenses can be difficult to use … the f/1.2 and faster … but these are exceptions and many times it’s how the lens is used. I hear less complaints about those difficult to use pieces than I hear about the 7D II … in just the time the 7D II has been out ….

Is this an industry wide trend / problem … Sony … Nikon … etc. … ? Maybe just a cost cutting trend (don’t have to pay for hands on QC, less training and a lower pay scale required for newer employees) … ?

I wonder if “does it focus correctly ?” be as important as shutter count at a later date … ?

Progress just doesn’t seem to be going in the right direction to me … but then again, that’s just me …

End rant,
Jefferson …



Dec 12, 2014 at 04:01 PM
KiboOst
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p.1 #2 · p.1 #2 · … A Few Canon Questions …


Sensors have more and more megapixels and people keep looking at pixel size. So it multiply any variations between models and ask for lot more demanding af. At a point that qc accepted variation level is too high.


Dec 12, 2014 at 05:16 PM
Alan321
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p.1 #3 · p.1 #3 · … A Few Canon Questions …


Jefferson wrote:
If my old 300 f/4L IS is sharp on my 5Dc, and sharp on my 1Ds2 … it should be sharp on a 1D IV and the new 7D II with very few exceptions … IMO


The lens puts an image onto the sensor but for a given number of pixels the 1D4 will be looking at a smaller part of the image than the 1Ds2, and the 7D2 will be looking at an even smaller part of the image. A certain amount of blur (due to focus error or diffraction or depth of focus away from the focus plane or image enlargement) that was tolerable on the 1Ds2 pixel density is therefore less tolerable on the 1D4 and 7D2.

However, a new camera with the same size sensor and same pixel density as the 5D or 1Ds2 should be just as forgiving as those older cameras.

In some cases we've just come to expect better from modern gear even if the equipment has much the same specification.

One thing is certain: getting the focus tuning correct can make a very noticeable improvement to your images when you zoom in on them with a big print or on-screen.

- Alan



Dec 14, 2014 at 07:40 PM
chez
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p.1 #4 · p.1 #4 · … A Few Canon Questions …


I think the camera manufactures were getting too many camera/lenses sent in for calibration under warranty so they came out with a process that relieves their burden on calibrating their products to acceptable levels.

I still send my lenses in if they are not right. I'd rather have it corrected in the lens than some fudge factor.



Dec 14, 2014 at 07:58 PM
scottam10
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p.1 #5 · p.1 #5 · … A Few Canon Questions …


Camera bodies and lenses work together. You can't normally place the blame squarely on either component individually.

There is an "allowable tolerance" for both camera bodies and lenses. A lens which is (say) +3 is within tolerance and will work well with a body which is (say) -3. A person who had that combination would be very happy and if they sold the lens they would claim "This lens focuses perfectly". If they sold it to a person with a body which is (say) +4, that person would be unhappy.

Before MA people would have to send it to Canon. Canon might tune that body and lens to work perfectly together, but that might cause problems with the AF performance of another lens in your collection (unless you're going to send your entire kit to Canon at the same time). MA gives us the option to do it ourselves.



Dec 14, 2014 at 08:32 PM
EB-1
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p.1 #6 · p.1 #6 · … A Few Canon Questions …


The 300/4 IS has marginal IQ on the periphery, so I'm not sure how it does on the 36MP bodies. That 1997 lens could use an update with fluorite glass, etc.

EBH



Dec 14, 2014 at 08:32 PM
Paul Mo
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p.1 #7 · p.1 #7 · … A Few Canon Questions …


Never AFMA'd a lens in my life... proud to (ignorantly?) say.


Dec 14, 2014 at 08:42 PM
EB-1
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p.1 #8 · p.1 #8 · … A Few Canon Questions …


Paul Mo wrote:
Never AFMA'd a lens in my life... proud to (ignorantly?) say.


Is that supposed to be a good thing? Not every lens/camera combination requires adjustment to focus accurately, but plenty do. Oddly enough the relative compensation of a given lens on different bodies does not necessarily follow a logical correlation with other lenses on that body. The values must be empirically determined at this point. IIRC Canon has a patent for an automatic AF calibration system, which perhaps will come in my lifetime.

EBH



Dec 14, 2014 at 08:49 PM
Paul Mo
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p.1 #9 · p.1 #9 · … A Few Canon Questions …


I think it's a good thing, but I could be wrong. Is it more a tele to supertele trend/need? Shooting mostly 24-200 I've never bothered. Just lazy I guess.


Dec 14, 2014 at 08:51 PM
Ferrophot
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p.1 #10 · p.1 #10 · … A Few Canon Questions …


I think it is only certain lenses that respond to AFMA. I have used it with good results on my 100-400L but my shorter lenses didn't need it due to wider depth of fields. Then, some long lenses don't need it at all. Just luck of manufacturing tolerances I guess.


Dec 15, 2014 at 12:49 AM
Gunzorro
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p.1 #11 · p.1 #11 · … A Few Canon Questions …


Paul Mo wrote:
I think it's a good thing, but I could be wrong. Is it more a tele to supertele trend/need? Shooting mostly 24-200 I've never bothered. Just lazy I guess.


Paul -- I have three bodies that allow AFMA, and each requires a different setting for the same lens. Each camera is pretty consistent as regards increments of change for each lens, but the range is different.

I don't find it makes a difference -- all my lenses needs some degree of adjustment.

Here are some examples.

16-35L II: 5D2, -6; 1D3, +5; 1Ds3, +5

17TSE: 5D2, -5; 1D3, +2; 1Ds3, -1

50L: 5D2, -7; 1D3, +5; 1Ds3, +5

28-300L: 5D2, 0; 1D3, +3; 1Ds3, -2

As you can see, none of these lenses has "zero" adjustment over three different bodies. The same holds true for all my lenses -- they all need some (usually minor) correction for best accuracy at a wide range of distances. I find that even a single increment of adjustment is noticeable in a lens, when viewed critically at 100% on repeated tests.

But, in the end, it's whatever you feel works for you!




Dec 15, 2014 at 10:08 AM
Alan321
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p.1 #12 · p.1 #12 · … A Few Canon Questions …


Unfortunately, we cannot yet tune our zoom lenses at different focal lengths simultaneously, and we cannot tune any of the lenses at different focus distances simultaneously. Sigma has provided that facility with some of their new lenses via a lens dock that connects to a USB port on a computer. Big brownie point for Sigma Big wake-up call for Canon and Nikon.

Back in the olden days we used low-resolution digital SLRs that could withstand greater levels of focus error before it became obvious. In ancient times film did the same thing. We also generally had small prints that did not magnify the image much.

Nowadays we can more readily see the effects of focus errors because there is so much more detail to be seen when it is correct that errors become obvious. We have bigger and better printers too. We have bigger and better monitors that can display far more detail than we ever saw on CRT monitors. All of these work against us when the focus is not quite right and work for us when it is spot-on.

Camera manufacturers still use optical focus tolerances that were less than wonderful decades ago and are even less appropriate now. Focus tuning is our only hope of overcoming this problem. Furthermore, the mechanical tolerances of the lens mount and sensor are only borderline acceptable, especially on the lighter bodies with heavy lenses hanging off them.

- Alan



Dec 18, 2014 at 12:09 AM
EB-1
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p.1 #13 · p.1 #13 · … A Few Canon Questions …


Ferrophot wrote:
I think it is only certain lenses that respond to AFMA. I have used it with good results on my 100-400L but my shorter lenses didn't need it due to wider depth of fields. Then, some long lenses don't need it at all. Just luck of manufacturing tolerances I guess.


The funny part is that I've rarely needed any MFT on any copies of the 100-400. I've had more need for MFT with 24-70s or 70-200s.

EBH



Dec 18, 2014 at 12:16 AM





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