Canon 24-105 - acceptable barrel distortion?

Started May 29, 2007 | Discussions
skeet25 New Member • Posts: 10
Canon 24-105 - acceptable barrel distortion?

As a new owner of this lens, I'm beginning to enjoy it and understand its limitations. I've heard mention of barrel distortion encountered in this lens in several posts in this forum when shooting at 24mm.

I'm shooting with a Rebel XT, and I am not going out of my way to look for this problem, but I've noticed it in several shots at 24mm. In an attempt to better observe this issue in the lens, I shot this picture of a fence at a distance of 5 feet, 24mm, f10.0:

The barrel distortion is quite pronounced, but the shooting conditions were a bit extreme. I shot the same picture with the kit lens at 24 mm and the vertical lines of the fence boards were significantly straighter at the edges.

If I'm seeing this much barrel distortion with a crop sensor, I can't imagine how bad it will be with the 5D, which I was planning to get later.

I would like to solicit input from the group:

  • Is this amount of barrel distortion "normal" for a 24-105 at the wide end? Do I have a bad copy?

  • Can it be calibrated out by Canon, or should it be returned to the vendor for another copy?

Thanks.

Hodgjy Senior Member • Posts: 1,865
Re: Canon 24-105 - acceptable barrel distortion?

Two things are going on here. 1) you have perspective and 2) barrel distortion.

Barrel distortion is unevenly pronounced when you have perspective differences. It looks like the plane of the fence was not parallel to the camera. Perspective comes from the planes not being even (like railroad tracks converging at the horizon, for example).

Your lens is fine. Use it and love it. Distortion is inevitable in zoom lenses. "Dud" lenses rarely have distortion problems--they mainly have softness, focusing, or chromatic aberration issues. Your lens is good and does not need to be fixed. I'm also fairly sure distortion isn't something that can be calibrated by service techs.

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Leon Wittwer Forum Pro • Posts: 13,525
Re: Canon 24-105 - acceptable barrel distortion?

There are a variety of software packages out there to correct lens distortion. Lens Doc has a plugin for PS that works in 8 bits. For 16 bit images, PowerRetouche has a plugin that works fine and that is what I use. When I got my 24-105, I just did a number of shots at different focal lengths to "calibrate" for removing any distortion. When I PP, I look at the focal length and do the correction from my calibration table.
--
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OP skeet25 New Member • Posts: 10
wall shot

Thanks for the feedback.

I really want to like this lens, and am still wondering whether the amount of distortion I'm experiencing is "normal" for a 24-105L.

This time, I was more careful with the perspective, and used a tripod. Here's a shot of a wall at 24mm, f4.0:

I was surprised that the barrel distortion drops off significantly at 28mm:

How do these observations match up with those of other owners of this lens?

Do you sub-consciously back away from 24mm and creep up to 28mm when doing architectural shots or group photos of subjects wearing striped shirts?

Hodgjy Senior Member • Posts: 1,865
Re: wall shot

You are still not totally square with the wall (look at the grass at the bottom), so barrel distortion will be exaggerated on the left side a little because of the converging planes.

Even so, with the slight exaggeration, your lens looks fine. Read this review, as it has a distortion test:
http://www.photozone.de/8Reviews/lenses/canon_24105_4_is/index.htm

As I said before, lenses can't really be defective for distortion. They are defective for sharpness and focus because of misalignment issues. Distortion is caused by the design of the lens--not by defects.

Enjoy your lens. It's a good lens.

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seattlesteve
seattlesteve Regular Member • Posts: 385
Re: wall shot

Hey Jay,

Are these types of distortion a plug-in like PTlens can fix?
Thanks,
-steve
--

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JoostA Regular Member • Posts: 324
Re: wall shot

I used to own a Digital Relbel XT (350d) and the 17-55 2.8 IS. Now I have a 24-105 with a 5D and the barrel distortion is significantly lower at 24mm than the 17-55 at 17 mms (which is actually close to 27.2 mm), so the 24-105 can go wider and has a greater zoom range, with less distortion.

I also love the color and contrast improvement compared to the 17-55. Finally, even though the 17-55 has better center sharpness, the 24-105 has better corner sharpness. Finally, except for 105mm @ f/4, I can see no overall difference in sharpness between the lenses in the field.

Also, when compared to the ultimate 24-70 f/2.8 there is no difference in sharpness, but the 24-70 does have less barrel distortion at 24mm and 2.8 to boot, so if you're really unhappy about this lense and you have the money and you don't mind the weight of the 24-70, maybe you should look at that one.

However, I think the 24-105 is a great all-round lense and I love the added reach, color, contrast, build and weathersealing I got when I went from the XT+17-55 to the 5d+24-105. You have a really great lense there if you ever think of getting a 5d.

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Canon EOS
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BG-E4
ef 24-105mm f/4L IS USM
ef 70-200mm f/2.8/L USM
ef 135mm f/2L USM
ef 50mm f/1.4 USM
430ex
ST-E2

JoostA Regular Member • Posts: 324
Re: wall shot

PS: I look at the barrel distortion differently. I love it, because it creates another creative possibility. I can use it for dramatic effects and if I don't want it, I can zoom up to 28mms or shoot at 24mm and take it out with PTlens, which needs no calibration for lenses or focal range.

Here is an example of a picture where I used the distortion to my advantage (or so I think) to add drama to an otherwise boring picture. There was some PP done. I converted it to B+W and added a little vignetting to give it the 'old photo look':

also, check out one of my first test pics with this lense, totally unedited: EOS 5d, ef 24-105mm f/4 IS, ISO 200, 24mm @ f/4, 1/25s, handheld. I love the 24mm and the close focus distance on this lense. I think it's cool:

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Don't chase what you want, embrace what you get

Canon EOS
5D
BG-E4
ef 24-105mm f/4L IS USM
ef 70-200mm f/2.8/L USM
ef 135mm f/2L USM
ef 50mm f/1.4 USM
430ex
ST-E2

OP skeet25 New Member • Posts: 10
Re: wall shot

Jay, thanks for the explanation.

JoostA - I agree with your assesment of improved colors and contrast with the 24-105. Comparing with a 28-135, I've experienced these differences.

I realize it is difficult to quantify barrel distortion without a test chart. What I was hoping for was that forum members with more experienced eyes will offer subjective opinions like:
a. this is similar to what I see with my lens, or
b. the distortion on your copy is significantly worse than on my copy.

Or, if I understood Jay's explanation, distortion is inherent in the design of the optical system, and within a narrow range, all copies of the 24-105 will exhibit it. Which in contrast to focus and CA issues are more related to tolerances in manufacturing. Did I get this right?

OP skeet25 New Member • Posts: 10
JoostA

Wow! Very inspirational work!

vin 13
vin 13 Senior Member • Posts: 1,481
Re: Canon 24-105 - acceptable barrel distortion?

The barrel distortion is quite pronounced, but the shooting
conditions were a bit extreme. I shot the same picture with the
kit lens at 24 mm and the vertical lines of the fence boards were
significantly straighter at the edges.

Are you happy with the lens apart from the distortion?
If so, I'm pretty sure you don't have a bad copy.

Barrel distortion is usually (if not always) at it's worst at a zooms shortest focal length.
Try the same shot with the 18-55 at 17mm!

My 17-40 has less (hardly any) at 24mm than the 24-105.
My 24-105 has less (none) at 70mm than my 70-200f4

Yes it's more pronounced on a 5D, however all the other benefits of FF outweigh this.
Distortion can be reduced (and sometimes corrected) in PS.

What's acceptable is up to you.

Personally I avoid using the 24-105 at 24mm, especially it there are straight lines at the edge of the frame.

The alternative is the 24-70f2.8

It's just as good, has less distortion at 24mm and an extra stop. On the downside it's bigger, heavier, has a smaller zoom range, no IS and a ridiculous hood.

cheers

Vin

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JoostA Regular Member • Posts: 324
Re: JoostA

thanks!

skeet25 wrote:

Wow! Very inspirational work!

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5D
BG-E4
ef 24-105mm f/4L IS USM
ef 70-200mm f/2.8/L USM
ef 135mm f/2L USM
ef 50mm f/1.4 USM
430ex
ST-E2

ChrisDM Veteran Member • Posts: 3,101
a 5D sample...

I've never analyzed my 24-105 for barrel distortion on my 5D, but I do have a recent photo here taken at 24mm. If mine shows distortion, it doesn't seem to show here. But if I were taking a photo of distinct rectangular lines which appeared skewed in any way, this would be easy to correct in PS. But I didn't have to do that to this photo...

skeet25 wrote:

As a new owner of this lens, I'm beginning to enjoy it and
understand its limitations. I've heard mention of barrel
distortion encountered in this lens in several posts in this forum
when shooting at 24mm.

I'm shooting with a Rebel XT, and I am not going out of my way to
look for this problem, but I've noticed it in several shots at
24mm. In an attempt to better observe this issue in the lens, I
shot this picture of a fence at a distance of 5 feet, 24mm, f10.0:

The barrel distortion is quite pronounced, but the shooting
conditions were a bit extreme. I shot the same picture with the
kit lens at 24 mm and the vertical lines of the fence boards were
significantly straighter at the edges.
If I'm seeing this much barrel distortion with a crop sensor, I
can't imagine how bad it will be with the 5D, which I was planning
to get later.

I would like to solicit input from the group:

  • Is this amount of barrel distortion "normal" for a 24-105 at the

wide end? Do I have a bad copy?

  • Can it be calibrated out by Canon, or should it be returned to

the vendor for another copy?

Thanks.

-- hide signature --
Rick Knepper
Rick Knepper Forum Pro • Posts: 17,870
Re: Canon 24-105 - acceptable barrel distortion?

Since I do not have any photos of straight lines shot from 5 feet away, I can not extrapolate any comparison. Do you have any "normal" landscapes?

To answer your question the best I can, I do not own a WA lens that does not have some distortion, and yes the 24-105 has some noticeable distortion at 24mm. I align my camera/lenses using a spirit level most times which minimizes the effect. I rarely hand-hold. Distortion is usually not the biggest problem with Canon WAs.

BTW, I have a $3000 lens whose distortion would probably make those lines look straight.

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Badbatz Senior Member • Posts: 1,914
Re: wall shot

What do you shoot? Architecture? Then get a specialized lens. VERY few wide-agle lenses are good enough for CRITICAL work in architecture so if you do architecture for a living, get a specialized rig (PC lens, such as TS or - better - a view camera.)

I use a 5D/24-105 combo w/o any problems. Yes, ithe lens does display some barrel distortion - esp. wide open - at the wide end (up to 28-30 mm) but so what? I don't use it for critical architecture shots and don't photograph rullers and brick walls. You know, for a walk-around lens "f/8 and be there..." and stop tormenting yourself.

IMO the 24-105 is the best general purpose IS lens for a FF camera on the market. Period.

penny2 Forum Member • Posts: 50
Barrel Distortion Correction

Bibble Pro is supplied with a database of Canon lenses and will correct barrel distortion of Raw and Jpg images.

The Bibble Pro database also allows Chromatic Aberration and Vignetting correction.B

In addition it is a good raw image processor. It comes with Noise Ninja although I have not needed to use this yet this since I acquired the Canon 5D recently.

Perspective correction is another matter entirely. Many learn to use this creatively. To fix this when needed you need a tilt and shift lens or software correction. Amongst many, a simple but versatile program is ACDSee, and more elaborate are Photoshop and Corel PhotoPaint etc.

cityphotog Senior Member • Posts: 1,337
on the left

side . And that also happens with the lens I use. It always affect the left side only (sorry but I didn't do a deep testings... Im just reporting what I see every day)

I have the feeling that the IS has something to do with this (the left side only). A friend also told me about it with his copy.

no distortion I see with the 24-70 but that one is not really 24mm but more like 25mm at the wide end, so it doesn't count for that.

OP skeet25 New Member • Posts: 10
Re: on the left

cityphotog - on the fence shot, there appears to be more distortion on the left. On the brick wall shot, the right seems worse. So, I believe it may be a perspective issue.

Thanks to everyone for their feedback!

cityphotog Senior Member • Posts: 1,337
Re: on the left

I was actually looking at the image posted by ChrisDM ...

in any case this "left side more distorted" thing is visible under any perspective, in many many pictures of mine.

I don't know what it is, but it's real. At least with two copies of the lens I had the chance to shoot with.

starting to believe that it may be the placement of the lenses to accommodate the stabilization.

Steve Balcombe Forum Pro • Posts: 14,558
Re: a 5D sample...

ChrisDM wrote:

I've never analyzed my 24-105 for barrel distortion on my 5D, but I
do have a recent photo here taken at 24mm. If mine shows
distortion, it doesn't seem to show here. But if I were taking a
photo of distinct rectangular lines which appeared skewed in any
way, this would be easy to correct in PS. But I didn't have to do
that to this photo...

http://www.pbase.com/chris_miller/image/75307427/original.jpg

That shot (nice, by the way) does show quite strong barrel distortion. The effect it has on that kind of shot is to make the pier 'bulge' towards the viewer. If you run a straight line along the fence rail, for example, you'll find it has a pronounced curve.

Hope you don't mind me using your shot for this demo...

Obviously the image quality is wrecked by converting it to a 256-colour animated GIF - this is purely to show the geometry. When you seen the original directly compared with a corrected version, the 'bulge' is obvious.

I have to fix up shots of rail maintenance vehicles in connection with an aspect of my work, so the effect of curved railway lines is very familiar to me!

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