Lens sharpnes when stopped down (Canon 28-135mm IS) - is this normal?

[angelika]

Hi,

I recently bought Canon EF 28-135mm f3.5-5.6 IS lens and... I'm a bit disappointed. I took quite a few pictures and

many of them seemed rather soft, especially those taken at the wider end. So I put the camera on a tripod and did

the "newspaper test" which was a bit suprising. At 28-100mm this lens is actually quite sharp (I mean okayish) wide

open but very soft (the pictures are almost out of focus) when stopped down to f6.3. It's fine at f3.5, f5.0 or f7.1

(being the sharpest at f8, and going soft at f11 again). At 100-135 it is more predictable (well to me anyway) as it is

soft wide open and sharper when stopped down, even at f6.3.

 

So is it normal for this lens to be so soft at f6.3? It may be a silly question but I find it quite frustrating - I try to stop

the lens down hoping to get a sharper picture and it turns out that I would be better off just shooting wide open...

Or am I expecting too much from this lens?

 

Sorry for not including any test pics here but I didn't really have time to crop them. In my test I used tripod, flash and

a remote control to eliminate any user errors.

 

Thanks for any advice.

[bobatkins]

It's not normal and hard to explain. I suspect user error.

 

Try the test again. Make sure you turn IS OFF and switch AF off once you have focus at a given focal length so that

the images at the various aperture settings have exactly the same focus setting.

 

Use a tripod of course, and if you don't have a remote release and the shutter speeds get slow, use the self timer.

You can also use mirror lock up with a remote release if you really want to get picky (though it shouldn't be

necessary with that lens).

 

At http://www.bobatkins.com/photography/technical/testing_lenses.html I have some additional comments on lens

testing which may help

[matroskin]

post some samples here. i mean, the images are soft compare to what lens(es)?<br>KN

[ed_v.]

I also own the 28-135 IS and have been disappointed with it's sharpness. I have not done as thorough a job at testing the lens as Angelika has, but have noticed that even when using flash and/or higher shutter speeds I still get soft pictures. In my case, most of the time it's likely user error, but I sometimes think it's the lens-camera combination (I'm using a Rebel XT). By comparison, I just purchased the 17-85 IS and find most images sharper under the same conditions.

[scherbi]

Yep. I have it too. Kit lens with my 40D. After purchasing the 85f1.8, I hardly ever used it because the IQ was no contest. Now, the 85f1.8 is a very fine lens, and prime so there is of course no contest, but I just never liked the look of the images from the 28-135. I also have the 10-22mm, the 100mm macro, and two manual olympus lenses (28f3.5 and 50f1.8) with an adapter. All of these far outperform the 28-135 in every respect (except for zoom range). I'm not sure exactly what's wrong with it; perhaps it's the way it's softness, bokeh, contrast and color combine to create an image is missing some magic that other lenses have.

[ed_v.]

"...perhaps it's the way it's softness, bokeh, contrast and color combine to create an image is missing some magic that other lenses have."

 

Bill--couldn't have said it better myself. I have the EF 50 f/1.8 II and at 1/5th the price it produces stunning images in comparison.

[colin carron]

I may have got a poor sample but my 28-135 mm IS was a very mediochre lens. It was outperformed by the 18-55mm kit lens. Comparatively the 70-300 IS (non-DO) which I now have is a much better lens though my benchmark for zooms remains the 70-200 f4 L .

[nhut-nguyen]

Try again at f/6.3 at 28-100mm. It is normal for this lens to be soft wide open, I used to own this lens and mine was like that. Images began to get sharper when stopped down and sharpest at f/8. Don't look for softness, look for detail, the detail maybe soft, all you need to do is adding a bit of sharpening in post processing and everything is good. Try the USM function in Photoshop, with amount = 120-150 %, radius = 0.3-0.5 and leave threshold at 0.

[PuppyDigs]

With FF, my 28-135 was sharpest at F11-16. With a 1.6x crop, you may start seeing softness due to diffraction at F11 and

higher. I have many sharp 11x14 prints from my 28-135 so it was pretty decent stopped down. I guess if you enjoy pixel

peeping not many lenses will past the sharpness test. I found its weakest point to be flare--useless for sunsets for night

scenes with streetlights. Of course I ditched it after using it for 7 years for an EF 24-105 4L and it's a couple levels better in

terms of contrast, sharpness, flare resistance and bokeh.

[chrissyone]

I have widely varying degrees of success with this lens. Sometimes I can't seem to make anything sharp, and sometimes

it's like a tack. <a href="http://wileytradegroup.com/jenn_example.jpg">Here is a shot I did the other night in the

studio,</a> and I'm pleased as punch with the sharpness, but as the focal length increases, it does seem to fall apart a bit.

I have not pinned down any specific areas where it will be predictably sharp or not, it seems to be all over the place.<br>

<a href="http://wileytradegroup.com/ivanclose.jpg">Here is another shot, 90mm @ 5.6</a>, and it's fantastically sharp. So

the lens is *capable*, but I never get the consistent results that I can get with a 16-35 L or a 24-105 L.

[chrissyone]

I should also mention that I'm using this lens on an XTi. I've also used the 17-85 EF-S kit lens and find it to be generally

inferior to the 28-135 in most instances, but I don't have an samples to back that up.

[angelika]

Hi, many thanks for your responses - much appreciated.<br>

I did the test again, this time switching the autofocus off, as advised by Bob Atkins (thank you). Now the results are

more what I expected - I mean the lens is soft wide open but the sharpness does improve when stopped down. I

did however notice that the autofocus isn't very reliable as even though the camera indicates that the focus has been

achieved I could see that lens frequently focused closer than I was aiming... I guess that's what gave me the very soft

results the first time round. So maybe it is not so much the lack of sharpness but the less than satisfactory

autofocus after all? Or is it just me?<br><br>

 

I have to agree with Colin - my kit lens seems to outperform this lens as well (when comparing the 28-55mm range)

which is a shame. I'm not a pro so I can't really justify buying an L lens but hoped that a few hundred pounds would

buy me at least something half decent.

I have a very old 100-300mm big and heavy Canon lens with a very slow (but acurate) autofocus, which cost the

fraction of

what I paid for the 28-135mm (which isn't getting any younger either) but it produces great pictures and the IQ is just

amazing. I don't use it a lot (far too heavy to carry everywhere) but I wouldn't sell it because I like it so much.

<br><br>

 

Anyway, I do have some sharp pictures taken with the 28-135 but I also have many soft ones - more than from the kit

lens so it is quite disappointing.<br><br>

 

I won't be posting all the test images (would be to boring to look at), just the 28mm test (100% crop):<br><br>

 

<a href="http://img146.imageshack.us/img146/595/28mmgm5.jpg">http://img146.imageshack.us/

img146/595/28mmgm5.jpg</a><br><br>

 

And some other pics taken when I was testing this lens earlier:<br><br>

 

<a href="http://img55.imageshack.us/img55/350/f5628mmap8.jpg">28mm f5.6 (unprocessed)</a><br><br>

 

<a href="http://img397.imageshack.us/img397/6743/f438mmoj6.jpg">38mm f4 (unprocessed)</a><br><br>

 

<a href="http://img397.imageshack.us/img397/9339/f8135mmpm8.jpg">135mm f8 (unprocessed)</a><br><br>

 

<a href="http://img361.imageshack.us/img361/3533/f8135mmusmja6.jpg">the same as above but sharpened</

a><br><br>

 

<a href="http://img361.imageshack.us/img361/8894/spain24322smjq1.jpg">handheld and sharpened</a>

[tdigi]

Angelika, I think you would be happier with a Tamron 17-50 or 28-75. When I got my 40D it came with the 28-135 and I

wanted to like it buy my Tamron blew it away. I ended up selling the Canon and keeping the Tamron until I moved to L

lenses.

 

Both Tamrons are about $400 US and both are 2.8.

[angelika]

I will probably sell it too, Tommy. Eventually. But I do use the longer end a lot so 17-50 or 28-75 will probably be too short, although the 2.8 would be nice...

[tdigi]

Its always a compromise, I find that usually 2 lenses are needed to cover a long range with some quality.

 

A 70-200 F4 and an 18-55 with IS or Tamron 17-50 2.8 may be a nice combo for you if money is an issue.

 

If not many suggest a 17-55 2.8 but I too prefer a bit more range and length. So I moved to a 24-105 and I recently

added a 70-200 2.8 which is an amazing lens as well.

 

With lenses you really get what you pay for. The Tamrons are very good but they don't have the focus speed of the good

Canons and the build is not as good either but they produce very good photos.

[Andy Collins]

I'm a bit surprised by the bad experiences with the 28-135. I've had a lot of very good success with mine, which

is why I've had it just about 10 years now. It isn't the sharpest wide open (but most lenses aren't), but it does

perform well at the middle aperture settings. I have had numerous primes and have had several (and still have) L

lenses, all of which have certainly outperformed my 28-135 (for the money, they'd better!), but overall it has

been a great lens in terms of its excellent focal range and in terms of delivering excellent images--maybe I got

a good copy. I actually owned and sold a 24-70L because the limited focal range was a constant irritant to me,

and while the 24-105L looks good, at this point it's not $800.00 better to me. I also like Tamron but I like

Canon's quiet USM AF and full-time manual focus capability much better, and as far as 2.8 vs. 3.5, the wider

aperture would be nice but I've learned to make very judicious use of the IS on this and other IS lenses to get

the most out of that feature and out of the lens itself. Work with it awhile...you may grow to really like it.

[raul_trifan]

It's strange, because my 28-135mm mounted on a XSi (450D) delivers pretty well. Actually, on f/5.6-f/8 the IQ is really good between 28-100mm and on f/8-f/11 is decent between 100-135mm. I took a lot of pictures at f/5.6 and f/8 and I have not complains...yet. Anyway, I am not going to compare it with an L-lens or with a prime, but the image is pretty decent, at least in my opinion. Probably the IQ is somehow improved because I'm shooting RAW and using a bit more of sharpening...I don't know.