EF 28-135mm USM IS Soft Focusing

Hey guys. I bought this lens almost a year ago used. Was happy with it at first. It took a fall earlier this summer in my golf bag (due to idiotic behavior from a friend). I evaulated it myself at the time and I didn't really notice that it was bad.

Recently I purchased a 50mm f/1.8 prime, and have been exclusivly using it for 2ish weeks. I went back to my EF 28-135mm and I'm not a happy camper. Images look quite soft. The one thing that I also notice is that focus is inconsistent from 28mm to 135mm. When I look at the distance scale on the lens, the point it focuses on at 28mm is further away than at 135. It seems like the lens is possilbly back focusing at 28mm. Is this normal for the lens from what other people have seen?

I know that some people have gotten good copies of this lens, and some people have had bad. I think it's generally known that this lens is softer than most. Right now I'm not sure if there is something wrong with it, or if I'm just getting used to sharper images and the softness of this lens is becoming apparent to me.

Next week my uncle (the guy that sold it to me) should be back in town. I'll have to borrow his 20D (my rebel doesn't have MLU) and do some test shooting with the lens to see if there is an focusing problem.

I guess the other thing I can do is go back through my library of pictures to see if they are any sharper than they are now.

my 28-135 has moments of utter sharpness, but other times it misses, but it could easily be user error for me. I'm sure that you're aware of the fact that as a whole, primes are sharper than zooms, but if your lens took a fall, it might be worth it to sent it into canon to get checked out.

the 50mm will pee on the 28-135 anyways, at least mine does..lol if you think its got issues, sent it in to canon, the worst thing that can happen is its in good shape and theyll just clean it for ya!

I'm not sure if it's on warranty any more. I have to check with my uncle that I purchased it from. If it's not under warranty does Canon charge to see if there is a problem with a lens?

I was also going to head over to my uncles and borrow his 20D, set it up on the tripod and check things out for myself.

deadpass wrote in post #2060470
my 28-135 has moments of utter sharpness, but other times it misses, but it could easily be user error for me. I'm sure that you're aware of the fact that as a whole, primes are sharper than zooms, but if your lens took a fall, it might be worth it to sent it into canon to get checked out.

mine was the same way. all that barrel slop just has to affect IQ.

ed rader

aacmckay wrote in post #2049455
Hey guys. I bought this lens almost a year ago used. Was happy with it at first. It took a fall earlier this summer in my golf bag (due to idiotic behavior from a friend). I evaulated it myself at the time and I didn't really notice that it was bad.

Recently I purchased a 50mm f/1.8 prime, and have been exclusivly using it for 2ish weeks. I went back to my EF 28-135mm and I'm not a happy camper. Images look quite soft. The one thing that I also notice is that focus is inconsistent from 28mm to 135mm. When I look at the distance scale on the lens, the point it focuses on at 28mm is further away than at 135. It seems like the lens is possilbly back focusing at 28mm. Is this normal for the lens from what other people have seen?

I know that some people have gotten good copies of this lens, and some people have had bad. I think it's generally known that this lens is softer than most. Right now I'm not sure if there is something wrong with it, or if I'm just getting used to sharper images and the softness of this lens is becoming apparent to me.

Next week my uncle (the guy that sold it to me) should be back in town. I'll have to borrow his 20D (my rebel doesn't have MLU) and do some test shooting with the lens to see if there is an focusing problem.

I guess the other thing I can do is go back through my library of pictures to see if they are any sharper than they are now.

let me put it this way:

it's a great lens until you know better !

ed rader

ed rader wrote in post #2061597
mine was the same way. all that barrel slop just has to affect IQ.

ed rader

Speaking of Barrel slop, I have seen a Hack to fix that somewhere on the web.. i think i have it saved on my work comp. ill check it tomorrow!

it is a softer lens but, also, knowing its limitations is a key to getting great shots from it.. i know, i got an amazing flower shot from it when i first got the 30D..

The focusing scale in the window is only accurate on this lens when used @ 135mm. that's the way it was designed. It'll show about 50% greater than actual distance when used at shorter lengths.
I've heard this is common for Canon zooms, because they're not "parafocal(?)"

Hmm that's interesting, and something that I thought about when I first saw this problem. After experimenting some more in ample light I found that the distance the scale was showing was more accurate in a well lit environment, even when the lens is @ 28mm. I think in low light it was backfocusing. I do notice that there is a bit of a difference on the distance indicated by the lens at the different focal lengths. I'm sure that you're right that it will change with the focal length. However what I was seeing in low light was more than just the scale being a little off. IT was indicating the object focused was 2x or more further away than it really was.

heres a lens test chart page you might find usefull when you test it again.. http://medfmt.8k.com/m​f/resolution.html

still looking for the hack to fix the lens slop..

Got it, here ya go.. I havent tried it yet because I really dont need to, zoom creep isnt to big an Issue for me as Im always zooming in and out anyhow and hardly ever shoot the same distance more than once..lol

http://eosdoc.com/manu​als/?q=ZoomCreep

I shot exclusievly with the 28-135 for over a year. It's a great lens, well, until you try a prime. I got the 85 1.8 and that stayed on my camera for portraits. That's when I joined the forum and all heck broke loose. "Oh, is that what my pictures are supposed to look like?" I didn't realize just how soft some of my pictures were. And I made a choice to try larger aperture lenses. I haven't looked back. I think the 50 1.4 or 85 1.8 are about as good as it gets under $400.

zacker wrote in post #2065393
Got it, here ya go.. I havent tried it yet because I really dont need to, zoom creep isnt to big an Issue for me as Im always zooming in and out anyhow and hardly ever shoot the same distance more than once..lol

http://eosdoc.com/manu​als/?q=ZoomCreep

Thanks for the links zacker. Luckliy I haven't seen any zoom creap yet. That fix doesn't look too hard though. I'm used to dissasembling expensive things and putting them back together. Part of my job, and I can tell you the things I'm used to taking apart at work are much more expensive than a lens. I have the nerves for it.

SuzyView wrote in post #2065431
I shot exclusievly with the 28-135 for over a year. It's a great lens, well, until you try a prime. I got the 85 1.8 and that stayed on my camera for portraits. That's when I joined the forum and all heck broke loose. "Oh, is that what my pictures are supposed to look like?" I didn't realize just how soft some of my pictures were. And I made a choice to try larger aperture lenses. I haven't looked back. I think the 50 1.4 or 85 1.8 are about as good as it gets under $400.

Yup that's what I'm seeing now. Like I said, I'm going to keep the lens around for now until I can afford to replace it. I have a wish list of lenses and once I complete it, (who am I kidding, a wish list is never ending), the 28-135mm will probably be redundent. At that point I may sell it, or keep it around as a "junker" that I'm not afraid of using in situations that I wouldn't use my more expensive lenses (when I own more expensive ones).