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Author Topic: 24-105 f4L on cropped frame  (Read 4532 times)

Greg D

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24-105 f4L on cropped frame
« on: January 15, 2009, 11:14:18 am »

A few months ago, after much thought and reading of reviews, etc., I bought a Canon 24-105 f4L lens to use primarily on a 450D (Rebel XSi).  I'll make a long story short:  I didn't set out to critique the lens, but in the process of figuring out what turned out to be a camera problem, I spent a fair amount of time pixel-peeping at test shots (dollar bill and bright paper taped to a door, camera levelled on tripod, mirror locked up, IS off.....).  Inevitably, I did some lens comparisons.  What I see is virtually no difference between this lens (24-105L) and the Canon 28-135 IS.  I see vanishingly tiny differences in color and brightness (couldn't say one was better than the other, just different), but if anything the 28-135 has a miniscule edge in small-detail sharpness.  Suffice to say I'd think they were the same shot unless seen side by side at 100%.  So I'm inclined to conclude that the value of this lens (in terms of IQ, that is - not build, durability, aperture at the long end, etc.) is wasted on a cropped-frame camera.  Would others agree, or am I missing something, or just crazy?
Thanks for ideas,

Greg
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DarkPenguin

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24-105 f4L on cropped frame
« Reply #1 on: January 15, 2009, 11:25:37 am »

Without seeing how you are doing your comparisons I'd have to go with "missing something" or "just crazy".
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stever

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24-105 f4L on cropped frame
« Reply #2 on: January 15, 2009, 12:13:07 pm »

i have a 24-105, 28-135 and 24-85 (the latter two left over from the bad old days of film).  i bought the 24-105 with a 5D and the combination has performed very well for me allowing excellent 13x19 prints with some cropping.  because of IQ issues with telephoto lenses and my 40D (which went to Canon once under warranty) i decided to jump into Imatest and spend considerable time figuring out what's going on.

cutting to the chase, i didn't find the center resolution of the 28-135 or 24-85 much worse than the 24-105 on the 40D or 20D.  i did find corner resolution to be worse and less consistent on the 24-85 and 28-135 to be noticeably worse even stopped down to f8.  the smaller sensor size of the 20D and 40D did nothing to mitigate corner resolution issues, if anything they are worse with the crop frame cameras than the 5D.  This may well be a result of front/back focus issues with the crop frame cameras which luckily the 5D doesn't seem to have.  i think the 24-85, and especially the 28-135 will show more lens-lens variation

in short, i'm not surprised that you don't see a great difference between the 24-105 and 28-135 on a crop frame camera.  i don't find either lens to be wide enough on a crop frame camera as a walk-around travel lens and need something like the 10-22 in addition.  unfortunately my 17-85 is inferior to all of the above
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Greg D

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24-105 f4L on cropped frame
« Reply #3 on: January 15, 2009, 02:11:04 pm »

Quote from: DarkPenguin
Without seeing how you are doing your comparisons I'd have to go with "missing something" or "just crazy".

Either or both of those are distinct possibilities.  As far as my method goes, for this particular test, I taped a dollar bill to a door panel.  Also taped two approx. 1-inch wide strips of gift-wrap paper to the door immediately above and below the bill (for some color).  I shot this straight-on with the camera levelled on a tripod, mirror locked up, IS off, eyepiece covered.  Took one shot each at f4 (or largest avail. aperture), 5.6, 8, 11 and 16 at about 70 mm, shooting raw.  Didn't move the camera or tripod between shots or lens changes.  Then looked at the results at 1:1 in Lightroom.  As I said, I started doing this looking for a sharpness problem (turned out to be an autofocus problem with the 450d), but couldn't help noticing differences (or lack thereof) in lenses.  (And the shots I based this judgement on were not from the suspect 450d, by the way.)  Does this seem like a valid approach?
The computer these shots reside on just has a dial-up connection, but I'll upload a couple shots via another computer tomorrow.

Thanks!
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Greg D

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24-105 f4L on cropped frame
« Reply #4 on: January 16, 2009, 08:39:49 am »

Quote from: DarkPenguin
Without seeing how you are doing your comparisons I'd have to go with "missing something" or "just crazy".


Attached are 2 shots (100% center crops), taken as described in my reply from yesterday.  Any feedback appreciated, if you can really discern anything from the jpegs.  (28-135 shot on left, 24-105 on right.)
« Last Edit: January 16, 2009, 08:42:31 am by grog13 »
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jpgentry

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24-105 f4L on cropped frame
« Reply #5 on: January 22, 2009, 11:24:10 pm »

What you have found out is exactly what the truth is... that the 24-105L is not a very sharp lens by any stretch.  The 28-135 is as sharp or sharper across much of the range.  The only advantage is build quality and the pretty red stripe at the end.  I have both.  I always use the "L" because it looks nicer on the end of the camera.

If you want to see how the two lenses compare check this out... http://www.the-digital-picture.com/Reviews...0&APIComp=2

Play with focal lenths and f/stop to compare.  35mm goes to the 24-105/ 28mm goes to the 28-135.  I have found this site to match very closely what I see with my lenses...

-Jonathan

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marc

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24-105 f4L on cropped frame
« Reply #6 on: January 23, 2009, 03:12:38 pm »

Quote from: jpgentry
The only advantage is build quality and the pretty red stripe at the end.

The 24-105 is also a stop faster from 85mm and up..
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Piboy

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24-105 f4L on cropped frame
« Reply #7 on: January 25, 2009, 02:48:47 pm »

Of course some of us had the 24-105 f4L forced on us as a kit when camera only option of 5D MKII was not available   at my local camera dealer.  After having it now it doesn't seem to add much over my old 28-135 IS.
PiBoy
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Sam W.
samwardphoto.com

Greg D

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24-105 f4L on cropped frame
« Reply #8 on: January 27, 2009, 02:58:05 pm »

Thanks for the thoughtful responses.  Seems to confirm that the 28-135 is a pretty good deal.  Also, looking through the resolution chart tests on the-digital-picture.com site seems to say a lot about the value of relatively inexpensive primes compared to very pricey zooms.  Hmmmmm.......
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