Lensrentals: 24-70L Sample Variation Explained

Excellent article by Roger!

Click here to read.

Apologies if this is a repost.

Awesome analysis. Maybe is the reason why for the love/hate relationship with this lens.

awesome article, thanks for sharing

It wouldn't surprise me that I tried one of the outliers when I decided between it and my Sigma 24-70 HSM. The Sigma was clearly the better lens in terms of optical performance.

Thanks for sharing. Now I'll be waiting to see the analysis on the 100-400.

that's a pretty interesting read.

Very interesting...certainl​y seems like a pretty weak design. Hopefully Canon has learned from it and has improved their zoom mechanisms in the lenses since.

Thanks guys, the kind words are appreciated!

SDiver, it's a pretty standard design, the exact same washers are used in other barrel zooming lenses, like the 24-105 which is nearly trouble free. It might be they just aren't up to carrying the weight of the 24-70s barrel, it's a heavy chunk of glass.

And DuBarry, I've started on the 100-400, but it's a difficult lens to test: the system has to be recalibrated between every lens, so it's going to take a couple of months to get enough copies to draw conclusions.

Roger

Roger Cicala wrote in post #13311447
Thanks guys, the kind words are appreciated!

SDiver, it's a pretty standard design, the exact same washers are used in other barrel zooming lenses, like the 24-105 which is nearly trouble free. It might be they just aren't up to carrying the weight of the 24-70s barrel, it's a heavy chunk of glass.

And DuBarry, I've started on the 100-400, but it's a difficult lens to test: the system has to be recalibrated between every lens, so it's going to take a couple of months to get enough copies to draw conclusions.

Roger

If the 24-105 is trouble free then its a poor design for the 24-70mm . I agree that it probably is effective but a design must scale with the size of the elements. It appears in this case that this wasn't done.

I am curious if you guys have measured off center-differences. I had a 17-55mm which was pretty badly decentered in the left 1/8 or so of the frame. Curious how common decentering is lens to lens.

And also, for my own sanity, have you experienced any complaints on the 24L II for autofocus accuracy? I, among others (even the reviews on Canon.com show this), tried 4 different copies of that lens and every one of them was horrible even after MFA in terms of consistency on my 7D. I tried one on a T3i and it performed well...since you have insight into the market I'm curious if you have seen this as well.

Great article.

Roger: I still want to know how many copies of the 24-70 2.8L II/IS you've tested

Interesting. I wonder if the differences might not be even more extreme toward the edges.

Odd that the 24-105L tested more evenly since it seems to regularly appear on both my favorite lens and worst L ever lists, perhaps more than any other lens. I can't say I was impressed with either copy I tried. Not as sharp as tamron 17-50 or 28-75 on APS-C or FF and the FF edges were not so hot even at f/8-f/11. Maybe I got two copies near the 600 end and the ravers got ones at the 750 end of the scale.

GT, we've tested about 115 copies so far. That's most of them, thankfully.

SDiver, we see decentering every so often, although almost always after a lens comes back from rental, very rare to see it in a new copy (it's happened, but not very often). Element tilt is the same way, rare, but it happens, and often after trauma.

The 24 issue we saw a lot at first, but haven't had much problem in the last 6 months or so. When it was happening it seemed you could microfocus adjust for say 15 feet, but that didn't help when you focused at 30 feet, etc. I'm totally speculating but I wonder if maybe the AF motor current settings (the lenses have a place where the factory adjust frequency and voltage passed to the motor) may have been wrong at first and they've corrected it, or maybe the mathematical AF algorithm? But I'm just guessing.

Wombat - the 24-105 was more even, but even the better zooms have some variation. One thing I've wondered with the different opinions on that lens are if it has something to do with where people shoot it. It's a bit softer from 85mm on up, but usually pretty sharp overall.

Roger

SchnellerGT wrote in post #13311585
Roger: I still want to know how many copies of the 24-70 2.8L II/IS you've tested

I don't think Roger was actually reading the question or wondered why the winking smiley was there......

Very interesting read! Thanks for sharing.

This would certainly explain why my initial refurb went "soft" after heavy use.

Roger--In your opinion could this be a do it yourself fix? And thanks for the information.