HELP 24-70 f/2.8 II Repair - Is this within spec?

[R1-7D]

After six weeks away, Canon finally returned my 24-70 f/2.8 II.

My complaint was a decentered element that I noticed using Reikan FoCal software because of the massive dips in the curve. Canon returned the lens to me saying they adjusted it and it is "within spec."

People who are familiar with this software, does this look like a "proper" repair and within spec?


This is before the "repair":

Before Repair by HadrianRobinson, on Flickr


Now here are three tests I ran this morning after receiving the lens back from Canon.

Test one:

Today Test 1 by HadrianRobinson, on Flickr


Test two:

Today Test 2 by HadrianRobinson, on Flickr


Test three:

Today Test 3 by HadrianRobinson, on Flickr

[R1-7D]

I should mention that the test was conducted at:

- 70mm at 3.5 meters.
- Peak search before the test.
- EV 11.4
- Center point focus with evaluative metering.

[takesome1]

No it is not normal at any focal length.

Not knowing how you set up, if your camera AFMA is proper or anything else I wouldn't say the lens is bad off or your testing is bad. Your results at first look like failed tests in your method.

If your set up is correct and you still get these results I would send it back again.

[takesome1]

I should mention that the test was conducted at:

- 70mm at 3.5 meters.
- Peak search before the test.
- EV 11.4
- Center point focus with evaluative metering.

When you run an aperture test it AF at the first, if it looses focus your results will look like this.

Make sure your viewfinder is covered. Check for possible vibration in your tripod.
Make sure you AFMA is correct. Make sure your target is the same height from floor as your camera, set up square and level.
Try it on both 5D II and 5D III bodies to see if you get the same results.

[R1-7D]

I should mention that the test was conducted at:

- 70mm at 3.5 meters.
- Peak search before the test.
- EV 11.4
- Center point focus with evaluative metering.

When you run an aperture test it AF at the first, if it looses focus your results will look like this.

Make sure your viewfinder is covered. Check for possible vibration in your tripod.
Make sure you AFMA is correct. Make sure your target is the same height from floor as your camera, set up square and level.
Try it on both 5D II and 5D III bodies to see if you get the same results.

Thank you for your reply.

The tripod and the target were level. I was very careful setting it up. The eye piece was also covered. I also tried on both the 5D II and 5D III with similar results.

I had also recalibrated the lens last night. It's at -1 Telephoto, and +5 Wide.


Unfortunately Canon has kept this lens for 6 weeks prior, which is longer than I actually had possession of it. I was 4 days past the return date when I first noticed the decentered element and the store I bought it from would do nothing for me in terms of exchanging it, so I sent it in.

[R1-7D]

For comparisons sake, here is an aperture sharpness test I took with my 100mm Macro L last night at 5.3meters from the target.


Screen Shot 2013-11-27 at 11.35.39 AM by HadrianRobinson, on Flickr

[takesome1]

If you are sure it an accurate test, this is not normal for this lens.

I have run the same test on several copies.

@70mm
Most copies would be at the best around F/4 with almost no drop of at f/2.8.
Some copies would  be sharpest at f/2.8.

The curve should remain almost level after f/4

[R1-7D]

If you are sure it an accurate test, this is not normal for this lens.

I have run the same test on several copies.

@70mm
Most copies would be at the best around F/4 with almost no drop of at f/2.8.
Some copies would  be sharpest at f/2.8.

The curve should remain almost level after f/4

I am sure it's accurate. It's how I have tested all my other lenses and I have never seen this.

Thanks for the input.

First to call the store I bought it from to chew them out for not giving me another copy and making me go through this, and then a call to Canon to see if I can get this replaced.

[R1-7D]

WARNING TO ALL CANADIAN CANON CUSTOMERS!!!

I just spoke with CPS on the phone. Basically they told me that my tests were inaccurate, that my lens was within specification, and that if I send it in again there would be a good chance of nothing being done.


I can't believe the poor customer service I received, especially after paying $100 for their damned CPS membership.

I am now going to sell the lens at a loss.

[mwh1964]

May you sell with the in depth explanation.

[R1-7D]

May you sell with the in depth explanation.

I'm an honest person, I'm not going to deal with someone unfairly. What's the purpose of your post?

[Mt Spokane Photography]

The lens has a problem!  It should be sharper at wide apertures than it is at f/10.   Send it back asking them to fix it or replace it.


You can see the combined results of  testing this lens by many users here.  Note, this curve is not the one given by your software, but is normalized.  there is no big dip at f/5.6, but there is a small one, and that might be caused by just a couple of lenses.  I'm sure that any obviously bad ones were not included in the summary.    You can't compare it with a different lens, each one has its own curve.




The tests done by photozone are here:  Note, f/10 is always the lowest resolution point when compared to wider apertures.

[iMagic]

If Canon Canada is giving you a hard time, why not repeat your tests using one of your other lenses as proof to Canon that your testing is not in error?

[sagittariansrock]

For comparisons sake, here is an aperture sharpness test I took with my 100mm Macro L last night at 5.3meters from the target.


Screen Shot 2013-11-27 at 11.35.39 AM by HadrianRobinson, on Flickr

Two questions:
1. Are you sure you are conducting the test right (no offense meant, but the chart for the 100L seems odd- sorry if I am reading it wrong).
2. Did you see evidence of decentering in actual images. If so, would you mind sharing?
Roger Cicala also advises a real-world test here: http://www.lensrentals.com/blog/2012/05/testing-for-a-decentered-lens-an-old-technique-gets-a-makeover
I am an interested party, since I recently bought this lens.

[Ruined]

This is part of the reason I am wary buying refurb lenses from Canon.  If they send back obviously broken stuff from repair and say it is "in spec," there is a good chance they would sell same said broken stuff in their refurb store as according to them it would be "in spec"...