Comments on: The Limits of Variation http://www.lensrentals.com/blog/2011/10/the-limits-of-variation Photo/video thoughts from the largest rental house Tue, 18 Jun 2013 13:47:01 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: Debashis http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-24654 Debashis Thu, 15 Nov 2012 02:59:15 +0000 http://www.lensrentals.com/blog/?p=3419#comment-24654 I had the same problem with my 5 month old, very sparingly used 24-70mm f/2.8 Mark I. Did a quick focus test using a chart and found lens back focused at 24mm (barrel extended position) by about 10mm-14mm. This I tested at two apertures that I normally use - f/2.8 and f/5.6. There was no perceptible focusing issue at 70mm (barrel retracted position). I also found a bit of lateral movement around the barrel which I suspected played a part in the problem at the 24mm end. Sent it to Canon repair and it came back today with 3 collars replaced. Haven't tested the lens yet but the lateral play around the barrel is no longer there. I just hope the problem has been fixed for good. Regards I had the same problem with my 5 month old, very sparingly used 24-70mm f/2.8 Mark I. Did a quick focus test using a chart and found lens back focused at 24mm (barrel extended position) by about 10mm-14mm. This I tested at two apertures that I normally use – f/2.8 and f/5.6. There was no perceptible focusing issue at 70mm (barrel retracted position). I also found a bit of lateral movement around the barrel which I suspected played a part in the problem at the 24mm end.

Sent it to Canon repair and it came back today with 3 collars replaced. Haven’t tested the lens yet but the lateral play around the barrel is no longer there. I just hope the problem has been fixed for good.

Regards

]]> By: Fabio http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-24322 Fabio Thu, 01 Nov 2012 13:31:58 +0000 http://www.lensrentals.com/blog/?p=3419#comment-24322 Hi Rojer, what is the test I have to do, if the lens is sharp or not? suguestao you have any? when I get my order, I can send you some images for evaluating? the lens will be sold for a shop, that also repairs lenses ... thanks for your help Reggards Hi Rojer,

what is the test I have to do, if the lens is sharp or not?
suguestao you have any?

when I get my order, I can send you some images for evaluating?

the lens will be sold for a shop, that also repairs lenses …

thanks for your help

Reggards

]]> By: Roger Cicala http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-24317 Roger Cicala Thu, 01 Nov 2012 12:36:16 +0000 http://www.lensrentals.com/blog/?p=3419#comment-24317 Fabio, Here are a couple of things I look for on 24-70 Canons. First, if there are dents in the filter ring, run away. That lens does NOT survive drops at all. Second, is it about as sharp at 24mm as at 70mm? The great majority of the problems we see affect either 24 or 70, but not both. Finally, is there any 'catch' in zooming or focusing? Broken collars in the helicoids are common and show up as a roughness when zooming and focusing. If there's a broken collar, the lens will be decentered. Fabio,

Here are a couple of things I look for on 24-70 Canons. First, if there are dents in the filter ring, run away. That lens does NOT survive drops at all.

Second, is it about as sharp at 24mm as at 70mm? The great majority of the problems we see affect either 24 or 70, but not both.

Finally, is there any ‘catch’ in zooming or focusing? Broken collars in the helicoids are common and show up as a roughness when zooming and focusing. If there’s a broken collar, the lens will be decentered.

]]> By: Fabio http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-24316 Fabio Thu, 01 Nov 2012 12:30:34 +0000 http://www.lensrentals.com/blog/?p=3419#comment-24316 Hi, I am about to buy a used MKI 24-70, the copy is UX0713 (Utsunomiya, 2009). when I saw this article I was "afraid" of buying. can tell how to make a fast screening if it is a good copy or not? right now i have 5d mkIII with 50mm f1.8 Best Reggards, Hi,

I am about to buy a used MKI 24-70, the copy is UX0713 (Utsunomiya, 2009).
when I saw this article I was “afraid” of buying.

can tell how to make a fast screening if it is a good copy or not?

right now i have 5d mkIII with 50mm f1.8

Best Reggards,

]]> By: Roger Cicala http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-18496 Roger Cicala Sun, 30 Sep 2012 16:48:59 +0000 http://www.lensrentals.com/blog/?p=3419#comment-18496 Charles, We do see some sort-off patterns. For example one period had lots of Canon 300 f4 IS lenses with electrical problems. Canon 17-55 f2.8 IS, Nikon 24-70 f/2.8 and many other lenses had problems in early years that disappeared in later years. But we don't have enough copies to determine certain problems in certain serial number runs. Charles,

We do see some sort-off patterns. For example one period had lots of Canon 300 f4 IS lenses with electrical problems. Canon 17-55 f2.8 IS, Nikon 24-70 f/2.8 and many other lenses had problems in early years that disappeared in later years.

But we don’t have enough copies to determine certain problems in certain serial number runs.

]]> By: Charles http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-18470 Charles Sun, 30 Sep 2012 09:03:45 +0000 http://www.lensrentals.com/blog/?p=3419#comment-18470 This is a fantastic analysis. Have you ever measured lens variation as a function of year and place of manufacture? I picked up a 50L yesterday, having sort of chosen between two copies my local store had. They were both acceptable, although the UA stamp copy (2012) seemed a smidge sharper than the UZ stamp copy (2011). Any data on this? I'm not so curious about this particular lens, just variation as it relates to manufacturing date in general. Of course, the two copies I looked at is way too small a sample size to make any generalizations. And my test of sharpness was completely unscientific (standing facing a poster on a wall and shooting at 1/160 s at f/1.2 then looking at the letters). Thanks for all of your excellent work! This is a fantastic analysis. Have you ever measured lens variation as a function of year and place of manufacture? I picked up a 50L yesterday, having sort of chosen between two copies my local store had. They were both acceptable, although the UA stamp copy (2012) seemed a smidge sharper than the UZ stamp copy (2011). Any data on this? I’m not so curious about this particular lens, just variation as it relates to manufacturing date in general. Of course, the two copies I looked at is way too small a sample size to make any generalizations. And my test of sharpness was completely unscientific (standing facing a poster on a wall and shooting at 1/160 s at f/1.2 then looking at the letters). Thanks for all of your excellent work!

]]> By: jseliger http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-17615 jseliger Wed, 12 Sep 2012 06:53:41 +0000 http://www.lensrentals.com/blog/?p=3419#comment-17615 Heads up: You have a typo here: <em>BTW, out of all the different Canon lenses, <strong>this the only</strong> one for which the bad lenses were not completely obvious at a glance</em> The sentence should read "this is the only one. . ." Heads up: You have a typo here:

BTW, out of all the different Canon lenses, this the only one for which the bad lenses were not completely obvious at a glance

The sentence should read “this is the only one. . .”

]]> By: Jani http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-7791 Jani Thu, 03 May 2012 15:44:44 +0000 http://www.lensrentals.com/blog/?p=3419#comment-7791 <em>plastic collars around them that keep the barrel tracking properly within it’s grooves</em> My OCD can't handle that apostrophe. (Yes, I'm just compensating for my feelings of inadequacy before such a mighty piece of research.) plastic collars around them that keep the barrel tracking properly within it’s grooves

My OCD can’t handle that apostrophe.

(Yes, I’m just compensating for my feelings of inadequacy before such a mighty piece of research.)

]]> By: Kai http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-6938 Kai Tue, 17 Apr 2012 03:49:13 +0000 http://www.lensrentals.com/blog/?p=3419#comment-6938 Hi Roger, Fascinating data and work (Engineers' hats off to you for that), but also somewhat scary to me since I have a 24-70mm that was used professionally by a relative for the first 4-5 years, before I got it. The data in your post got me thinking, since my relative was unhappy about the sharpness of the copy and had switched to a 50/1.4 for portrait work (that's how I got it). So armed with a print-out of the post, I handed in my 24-70mm to Canon Tech service. Guess what: they replaced 3 collars and the lens feels a lot better now (haven't had time to shoot yet). I had always noticed how the barrel would feel loose and could be rocked from side-to-side when zoomed to 24mm, but this is all but gone now. A big thanks to your dedicated work! Kai Hi Roger,

Fascinating data and work (Engineers’ hats off to you for that), but also somewhat scary to me since I have a 24-70mm that was used professionally by a relative for the first 4-5 years, before I got it.

The data in your post got me thinking, since my relative was unhappy about the sharpness of the copy and had switched to a 50/1.4 for portrait work (that’s how I got it). So armed with a print-out of the post, I handed in my 24-70mm to Canon Tech service. Guess what: they replaced 3 collars and the lens feels a lot better now (haven’t had time to shoot yet). I had always noticed how the barrel would feel loose and could be rocked from side-to-side when zoomed to 24mm, but this is all but gone now.

A big thanks to your dedicated work!

Kai

]]> By: Roger Cicala http://www.lensrentals.com/blog/2011/10/the-limits-of-variation/comment-page-1#comment-2682 Roger Cicala Thu, 15 Dec 2011 03:10:19 +0000 http://www.lensrentals.com/blog/?p=3419#comment-2682 We have opened up a number of 24-70s for other reasons (sand or grit in the zoom, etc.) and have only found the broken collars in our older lenses that had resolutions problems, so far. But it's certainly possible some break with no effect on resolution. Roger We have opened up a number of 24-70s for other reasons (sand or grit in the zoom, etc.) and have only found the broken collars in our older lenses that had resolutions problems, so far. But it’s certainly possible some break with no effect on resolution.

Roger

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