EF 24-70 MkII: Erratic performance

I bought the EF 24-70 MkII 3 days ago from B&H to use with my 60D camera.

First thing I did was to test the 24 mm FL and the 70 mm FL against a target approximately 20xFL away. The quickie results were OK so I waited for later in the day to go on a photo walk in the neighborhood.

I came back with the largest percentage of non-keepers ever.

A lot of the non-close up photos came out well, with impressive rendering and sharpness.

The close-ups, although nowhere near the MFD were in the most part an unmitigated disaster. Front-focused, back-focused and some sharp focused.

Here are a couple of nice examples:

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Do not jump to conclusions when focusing on a inclined plane...the sensor has no idea precisely where it is to measure...anywhere within the zone of the sensor is fine, according to its programming.

Focus on a flat plane which is PARALLEL to the sensor; evaluate accuracy of focus by looking at an inclined plane

Wilt wrote in post #15947541
Do not jump to conclusions when focusing on a inclined plane...the sensor has no idea precisely where it is to measure...anywhere within the zone of the sensor is fine, according to its programming.

Focus on a flat plane which is PARALLEL to the sensor; evaluate accuracy of focus by looking at an inclined plane

+1. And use a live view focused shot (5x) as your reference to compare.

Hmmm...looking closely at the OP focus target, perhaps that checkered area is parallel to the focal plane.

Anyway, a target like this to focus, and and inclined plane to evaluate. Mimic the setup, this isn't a test shot (nothing perpendicular to the focal plane in this shot, but merely illustrates the test setup concept.

Fair enough you have used a graph to test the focus, I used several examples of this lens at a less than ideal setting of a trade show and found very similar results to what you have, don't really need to get back into that one.

As you own the lens use it in everyday situations and if not pleased send it back for a replacement, it cost some serious money so should be stellar at every focal length.

One test you could use is Reikan Focal calibration software, it takes the guess work out of what the human eye see's, do a search on it on here..

As for live view I like my lenses to focus correctly when I look through the viewfinder not when I faff about looking at the LCD..

You might not be able to evaluate backfocus vs. frontfocus, but when the camera is on a tripod it does allow to verify ACCURATE focus, with a camera which is NOT moving through space for each shot (photographer swaying).

Folks, the chequered panel is the target. Ideally I try to focus at the interior corner of a 3x3 square, so that there is more target area than the AF center square.

The target was painstakingly oriented for its plane to be perpendicular to the lens axis, ensuring right angles in the horizontal (by use of a drafting triangle and sighting the line) and vertical (eyeballing the tripod axis which is plumb by the use of the level at right angles and the lens axis).

The target is at 45 degrees to the graduated scale, because it is measured and the whole contraption is taped to the base, to maintain the geometry. The scale is graduated, so that 1 for example represents 10 mm on the lens axis.

The only subjective part is me eyeballing the limits of DOF so I can pronounce the front/backfocus amount.

I have done less extensive tests with all my lenses, I never had to deal with such erratic behavior.

Regarding the use of Live View, I tried it with significantly worse results. Truth to be told with lesser light too...

The question is for the users who tried some tests with the 24-70 MkII.

Q: Is it normally erratic, or I just got a quirky copy?

Shooting a small target and a sloping scale only works if your camera body and lens functions perfectly. It won't say much if there is something less than perfect going on.

MakisM1 wrote in post #15947797
Folks, the chequered panel is the target.

Regarding the use of Live View, I tried it with significantly worse results. Truth to be told with lesser light too...

I would first try a different/better target. It can focus on the chess board but IMO that target is not good enough to know 100% there's a problem. I'd also compare with Live View imediately in the same conditions e.g. take a photo using the viewfinder, then the same photo using LV.

I have used this target/method with my EF 50 f1.8, the EF 70-200 L MkII and the EF-S 18-200. These lenses gave consistent and predictable results. It's not the target or the method.

The EF 24-70 MkII has already given me unpredictable results in the field, which prompted me to do a very detailed test program. This zoom will front focus at one FL, back focus in another, even change focus between different apertures and definitely between distances.

My problem is that the 60D does not have MFA. If the AF was consistent (say front focus...) I could send it to Canon and have it calibrated. I am afraid though that with such complex behavior, I might need to help with on camera MFA which I don't have.

..and there is no hope of buying the 5DIII in the near future after spending a bundle on the EF 24-70 MkII...

Wilt wrote in post #15947541
Do not jump to conclusions when focusing on a inclined plane...the sensor has no idea precisely where it is to measure...anywhere within the zone of the sensor is fine, according to its programming.

Focus on a flat plane which is PARALLEL to the sensor; evaluate accuracy of focus by looking at an inclined plane

Surely the black/white squared section is hinged out for that very reason? Seems a perfectly valid set of results.

The mk2 24-70 is less than stellar in my book. Yes, its better than the mk1, but I expected more.

MakisM1 wrote in post #15949013
I have used this target/method with my EF 50 f1.8, the EF 70-200 L MkII and the EF-S 18-200. These lenses gave consistent and predictable results. It's not the target or the method.

The EF 24-70 MkII has already given me unpredictable results in the field, which prompted me to do a very detailed test program. This zoom will front focus at one FL, back focus in another, even change focus between different apertures and definitely between distances.

My problem is that the 60D does not have MFA. If the AF was consistent (say front focus...) I could send it to Canon and have it calibrated. I am afraid though that with such complex behavior, I might need to help with on camera MFA which I don't have.

..and there is no hope of buying the 5DIII in the near future after spending a bundle on the EF 24-70 MkII...

Well I think you have answered the question yourself, erratic to you in the field + erratic under test conditions = send the duffer back.

I wouldn't want to put up with unpredictability in a 50 f1.8 without a $$$$ top end L.

murkeywaters wrote in post #15949058
Well I think you have answered the question yourself, erratic to you in the field + erratic under test conditions = send the duffer back.

I wouldn't want to put up with unpredictability in a 50 f1.8 without a $$$$ top end L.

Oh yes, this baby is going back today. The question in my mind is whether I should try again, or ask for a refund and work a different strategy (primes?..)

MakisM1 wrote in post #15949066
Oh yes, this baby is going back today. The question in my mind is whether I should try again, or ask for a refund and work a different strategy (primes?..)

Don't get started on L primes, its a slippery slope!!

Seriously I was looking to buy a 24-70 mk2 and after trying several out at a trade show I got to say I wasn't impressed with the results at all, many are happy with their copies but also I just couldn't get excited about it as it is a standard lens.

I kept my 24-105 and bought a 35L, now that 35 L is really a great lens and goes well with my 85L and 135L.

Some people have had 2 or 3 copies of the 24-70 mk2 but when they have the right lens then it makes it all worth it, if you need that type of lens just keep going until you find a great copy.

Oh I know! When it's good, it's really good, but when it's bad it's rotten!... I want the standard zoom at f2.8... I am leery about changing lenses in the field (long time ago I dropped my 135 in the excitement of things and it died... the experience has stayed with me...).

The lens has a September 2012 date code, which is rather early (or maybe it's a return?... I don't think B&H would do that). Maybe I should wait for a later batch.