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Author Topic: Any guidance for how to test a new 24-70L?  (Read 4878 times)

nedavve

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Any guidance for how to test a new 24-70L?
« on: March 07, 2007, 05:03:06 am »

Hi,

I recently bought my first high-profile (ok, not a Hasselblad...) lens, a Canon ef 24-70L, to be used currently with my 350D. My experience so far has been great, fast focus, nice colours, sharp pictures (+ I get a free workout when moving the camera around).

However, after reading about a trillion threads about poor QC and that many people only settle for their 21 copy (ok, I am slightly exaggerating but you know what I mean), I got quite nervous that I spent $1300 and did not get a good copy.

My problem is that since I am a relative beginner, I don't relly know how to assess my copy, and have two problems:

1. I don't have access to an established "good" copy to benchmark my own against; I only have the ef 28-200 and the ef 50 1.8 to compare with (and the 24-70 certainly stand up, but I had hoped for nothing less). Are there example pictures somewhere from a sharp copy which are not "downsized for the web" and complete with info on exact focal length, aperture etc. so that I could get a little bit of sense of what to expect?

2. (This could be pure garbage based on my own misunderstanding, but if so I would like to know! ) Since I am using the lens on a 1.6 crop camera, am I right to think that I am currently not using "outer region" of the lens, which is (I guess) the area where most problems with quality tend to occur? My understanding is that the small sensor just takes the centered 1/1.6 fraction of the full frame, which would mean that I would never use anyting outside the 15mm distance from the center (so that for example the relevant range of the MTF charts is only 0-15 mm for the 350D). If this is true, I guess it means that I must find a FF body to be able to  fully evaluate my copy (I can return the lens now, but not by the time that I can afford to by a 5D myself...).

Thankful for any input.

Dave
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Ronny Nilsen

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Any guidance for how to test a new 24-70L?
« Reply #1 on: March 07, 2007, 07:35:21 am »

Quote
1. I don't have access to an established "good" copy to benchmark my own against; I only have the ef 28-200 and the ef 50 1.8 to compare with (and the 24-70 certainly stand up, but I had hoped for nothing less). Are there example pictures somewhere from a sharp copy which are not "downsized for the web" and complete with info on exact focal length, aperture etc. so that I could get a little bit of sense of what to expect?

[{POST_SNAPBACK}][/a]

Have a look here: [a href=\"http://www.ronnynilsen.com/Photography/Equipment/Test/24-70vs24-105.shtml]lenstest[/url]
to se some samples at 100% crop of another 24-70 to compare against.

Most lenses are usually good, you have to factor in that you will hear about all bad examples on the net, but people with good copies never speak up.  
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Ronny A. Nilsen
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D White

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Any guidance for how to test a new 24-70L?
« Reply #2 on: March 18, 2007, 12:42:26 pm »

The good copy / bad copy thing is way overdone. I have had maybe 15 L series lenses from Canon and the only issue was an 85 f1.2L that had the auto-focus point off, (back focus). This problem become obvious very quickly and is not an optical thing. Most people complaining about a bad copy will either have a back focus problem or they are expecting too much out of a retrofocus fast wide angle zoom.
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jani

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Any guidance for how to test a new 24-70L?
« Reply #3 on: March 18, 2007, 05:34:43 pm »

Quote
The good copy / bad copy thing is way overdone. I have had maybe 15 L series lenses from Canon and the only issue was an 85 f1.2L that had the auto-focus point off, (back focus). This problem become obvious very quickly and is not an optical thing. Most people complaining about a bad copy will either have a back focus problem or they are expecting too much out of a retrofocus fast wide angle zoom.
And many cases of back focusing can be fixed by using your local service center.

However, in the case of 24-70 lenses, I know from informal testing that at least one person in Norway has a better sample of the lens, yet my sample certainly doesn't seem to be as bad as what the "bad samples" are.

Ronny's 24-105 is, apparently, a "good sample", and I'm only slightly envious. I like the stabilizer very much.
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Jan

Carl Harsch

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Any guidance for how to test a new 24-70L?
« Reply #4 on: March 18, 2007, 08:36:33 pm »

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Most people complaining about a bad copy will either have a back focus problem or they are expecting too much out of a retrofocus fast wide angle zoom.
[a href=\"index.php?act=findpost&pid=107291\"][{POST_SNAPBACK}][/a]


or they spend way too much time taking pictures of rulers, test patterns, and measuring pixels than they do using the lens  
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elkhornsun

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Any guidance for how to test a new 24-70L?
« Reply #5 on: March 19, 2007, 05:09:00 am »

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or they spend way too much time taking pictures of rulers, test patterns, and measuring pixels than they do using the lens   
[a href=\"index.php?act=findpost&pid=107373\"][{POST_SNAPBACK}][/a]

The problems with back focus with the Canon 24-70mm are well known and many working pro's have switched to the Tamron 28-75mm f2.8 or to using primes as a result. Even with CPS it is a pain to have a lens at the shop when you need it for an assignment.

Not everyone may notice the problem or they may ascribe the problem to their own improper technique, assuming that a Canon L lens must be perfect from the factory.

The problems with the 24-70mm f2.8 have been so severe in the lenses I have seen that the images at the 24mm setting, where DOF should mitigate in part, were unusable.
Of course I look at 1000 images a week shot by people using the 24-70 so I am more aware of the shortcomings of this particular lens.
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nedavve

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Any guidance for how to test a new 24-70L?
« Reply #6 on: March 19, 2007, 01:03:11 pm »

Thanks for the input. I've now shot around 600 frames and am quite pleased with the results; they look all ok to me. The "softness" at 2.8 is reasonably comparable with the above posted pictures, so I am all happy.   Except that the lens is so heavy that my somewhat plastic 350 actually makes cracking noises when moved around fast   . Looking forward to the large grip-size of the 5D as well...
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deanjay

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Any guidance for how to test a new 24-70L?
« Reply #7 on: July 24, 2007, 11:37:56 pm »

I've had this lens (24-70mm 2.8L USM) since February, and it has been back to the Canon repair center twice -- without success. Zooming from 24mm to 28 or 30mm it very tight, as though something is sticking -- it binds and jerks. This happens only when the lens is in horizontal (landscape) orientation; it zooms relatively smoothly when rotated to portrait orientation, bottom-side-up, or aimed at the ceiling. And it's smooth when zooming from roughly 30mm to 70mm. The repair center first replaced a collar, which didn't help, then replaced a zoom key, which didn't help either.

Has anyone else observed this problem? It doesn't seem as though an "L" lens should work this way.
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jonstewart

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Any guidance for how to test a new 24-70L?
« Reply #8 on: July 26, 2007, 06:41:37 am »

Quote
Except that the lens is so heavy that my somewhat plastic 350 actually makes cracking noises when moved around fast   . Looking forward to the large grip-size of the 5D as well...
[a href=\"index.php?act=findpost&pid=107512\"][{POST_SNAPBACK}][/a]


Quite funny. I handled a 350D for the first time a few weeks ago, and thought it was lightweight!

Then I suggested the owner (who only had a kit lens) try some of the L's I had. Taking the kit lens off I nearly dropped! There's more weight in a McDonalds happy meal toy!

:grin:

Hope you are enjoying your new lens...watch out for the onset of RSI!

(Please don't take offence! I just mean this post humourously, not condescendingly)
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