Lens Decentering??

[Angel Ariel]

Update: New Image Symmetry shots from Saturday morning

Video with IS Noise

I bought a used Canon 17-55 f/2.8 lens last week, and I finally got the chance to take some test shots to check for decentering as was suggested here. Here are the shots I took tonight of the brick on the front of our house. They were taken at a slight angle (I am on teh driveway, slightly angling left toward the brick, but just very slightly), but every shot was taken from the same position, and the camera was held level at eye level (not angling down or up).

I am looking at the photos tonight, and I am concerned about decentering, especially at f/2.8-f/7.1. The corners at f/8 and above seem to be a bit more equal, but at the f/2.8-7.1 lengths, the upper left and lower left look much less sharp than the upper and lower right corners. (I am looking at the pictures at about 200% zoom, as was suggested here also).

Is this what decentering looks like? I have a 2 week return period on my lens that I am still in, but tomorrow is my last opportunity to return the lens in that 2 weeks as I won't be able to get to the shop again before the two weeks is up. If it's a better bet to just return the lens and go with a new lens, that's definitely an option.

ny help or insight anyone can share would be great!

 

[photo_chick]

If you suspect any issues with a lens the first thing you need to do is perform a proper focus test. Bob Atkins has a good walkthrough of how to do this properly on his site.

Don't pixel peep. At 200% nothing looks good. You're only going to have one plane of focus. It doesn't matter what your aperture is set to, depth of field is only the area of acceptable sharpness. That area, just in front of and behind the plane of focus, looks darn soft if you're viewing an image at 100%, much less at 200%. If you were at an angle to the wall, as you said, and were hand holding then that thin plane of focus is going to move all over the place. The bottom line is you can't tell if there are any issues with what you shot because it's not a proper focus test.

 

[Angel Ariel]

I did take a look at the Bob Atkins site, and I will hopefully be able to do his focus test tomorrow. but I think the advice I was given, which is what I took the pictures for tonight, falls under what Bob Atkins' site refers to as "image symmetry check". I'm concerned because I can see symmetry issues without zooming in at all - esp. at f/2.8...but when looking at the 4 corners like the symmetry check recommends, it's very evident that the 4 corners aren't the same.

I will re do this again in the morning and be properly squared and see if it changes anything (along with doing the focus test).

 

[Angel Ariel]

OK, so I was talking to mom2rtk in PM and I mentioned to her that I heard a sound from this lens after taking a picture..it's a whirring sound, and then a bit more audible of a click. She suggested I try videoing it, so I have. Here's the link to that video. The whirring part happens immediately after shutter release (it isn't as audible on the video) and continues until the more audible click happens at the very end. This sound doesn't occur using my kit lens (18-55) or the f/1.8 50mm. The 70-300 I have had for a few years now does make a sound as well, but not quite the same sound as the 17-55 f/2.8 is making. I don't think it's body related. Mom2rtk suggested I try turning off the IS and see if it made a difference..it did. As soon as IS was off, the sound stopped. Is an issue with the IS fixable?

 

[photo_chick]

Having the camera properly squared will make a pretty big difference in the results. Also keep this in mind, I'm quoting from that site here "Of course as in most things, if you look closely enough with a big enough microscope, you'll see differences, but they should not be obvious without extreme pixel peeping." Viewing at 200% is extreme pixel peeping. My experience with a misaligned lens was extremely obvious. Like no matter how much I squared my lens to the target it looked like I was shooting it at an angle as far as where that plane of focus fell. I am in no way saying you do not have an issue with your lens here. Just make sure you know how to properly check for the issues you think you may have and know that there is some variation across lenses in good working order if you loo closely enough.

Now... as far as the IS noise... different lenses make different sounds. I've got one that's really loud and one that's nearly silent. You could always go to a camera shop and check it next to a new copy of the lens. But here's the thing, it seems like you're obsessing over things that might be wrong with this lens. And that's not a bad thing when buying used. But my experience is that if you feel iffy about the lens at purchase then you're always going to feel that way no matter what you're testing reveals so you're probably better off returning it just for your own sanity.

 

[Angel Ariel]

Having the camera properly squared will make a pretty big difference in the results. Also keep this in mind, I'm quoting from that site here "Of course as in most things, if you look closely enough with a big enough microscope, you'll see differences, but they should not be obvious without extreme pixel peeping." Viewing at 200% is extreme pixel peeping.

I just want to clarify that the below is what I was looking for at the 200% (from teh atkins site)

This means that whatever image aberrations you see in the top left corner of the image, you should also see in the same relative position and to the same degree in the top right corner, bottom right corner and bottom left corner. It doesn't matter if the lens isn't sharp, or if it shows a lot of chromatic aberration, distortion, field curvature or other optical aberrations. If you take a picture of a flat subject (a wall or a page from a newspaper for example), and the camera is properly squared on to the subject, the four corners should look equally good (or bad) - as should the left and right or top and bottom halves of the image.

I know at 200% (which is what was suggested to me here on another thread) there will be aberrations, but I had read and was told that whatever the aberrations were they should look equal in all 4 corners..that's all I was looking for.

Now, that said, I did go and retake the photos this morning and did fully square myself, and kept the lens fully zoomed out, and I am not seeing the same issues so that was clearly a mistake on my part so thank you for bringing that up

Now... as far as the IS noise... different lenses make different sounds. I've got one that's really loud and one that's nearly silent. You could always go to a camera shop and check it next to a new copy of the lens.

My concern is stemming from another poster here telling me she doesn't remember her same lens ever making noise like that, so that does concern me.

But here's the thing, it seems like you're obsessing over things that might be wrong with this lens. And that's not a bad thing when buying used. But my experience is that if you feel iffy about the lens at purchase then you're always going to feel that way no matter what you're testing reveals so you're probably better off returning it just for your own sanity.

I'm not obsessing at all, and I'm sorry it's coming across that way. This is my first time buying a used lens, and I'm trying to do my due diligence in making sure the lens is working correctly. I will be the first to admit that I am a beginner in the photography world, and while I can google checklists of what to look for in a lens and such, I'm not always confident that I'm understanding it correctly or seeing it correctly..so I figured I'd come to a place where I knew there are many more skilled photographers than I for advice

At this point I do think I'm going to see if they have a new lens to listen to them side by side because the noise on the IS would be an issue for me..if the new lens didn't make the sound, and the used lens does, I'd be returning the used lens. It's audible to the point that if it isn't just a natural part of the lens, then it's worth returning. Hopefully they will have some new ones in stock..they didn't when we were buying the used lens.

 

[mom2rtk]

So I dug out the old T2i and that lens. I was surprised to hear that mine actually does make a tiny sound, emphasis on the word tiny though. I've had lenses that were a lot louder, so maybe that's why I never noticed this.

I couldn't make out the noise in your video though (just the shutter releasing). So I really think it would be very helpful (as Danielle suggested) for you to put a new copy on and see if it's the same way. I hope they have some new copies in stock you can try.

 

[WilsonFlyer]

I'd be willing to bet you an inordinate amount of money that your lens is fine. If you play this game long enough, you can find something wrong with everything you have. Stop being obsessed with what you read in an internet thread somewhere and go enjoy your new lens. You can always spend $300-400 more and get a new one that does the same things if it makes you sleep better.

I've played the game you're playing with yourself with almost every body I've ever bought (NEW) and it almost drove me insane until I STOPPED.

Use it to take pictures of persons, places and things and not bricks in your house. It is absolutely THE best EF-S lens Canon makes and that covers some ground. Mine stays on one of my crops virtually ALL the time.

 

[mom2rtk]

Angel, what is your reaction when you take shots of people and things around your house? The very first time I used it to shoot some random pics of Katie, my response was "wow". It was that much better than what I had ever gotten with a kit lens.

 

[photo_chick]

I totally get wanting to make sure it's right. But you gotta stop pixel peeping! It's a one way trip to crazy town when you start looking at things that closely. The next thing you know you're thinking all your lenses are broken (I got to that point when I first went digital) and you're ready to chuck them all out the window. I'm saying this a little tongue in cheek, but you really can drive yourself batty examining things too closely. Humans are not machines and you will never get that camera completely square. You could use a copy stand and it would still likely be a hair off at minimum. And that will show when you're looking that closely. This is why you view the image at a "normal" size when you're doing the initial evaluation for these tests. Then if something screams at you as being off, you examine it more closely.

 

[WilsonFlyer]

I totally get wanting to make sure it's right. But you gotta stop pixel peeping! It's a one way trip to crazy town when you start looking at things that closely. The next thing you know you're thinking all your lenses are broken (I got to that point when I first went digital) and you're ready to chuck them all out the window. I'm saying this a little tongue in cheek, but you really can drive yourself batty examining things too closely. Humans are not machines and you will never get that camera completely square. You could use a copy stand and it would still likely be a hair off at minimum. And that will show when you're looking that closely. This is why you view the image at a "normal" size when you're doing the initial evaluation for these tests. Then if something screams at you as being off, you examine it more closely.

YES! THIS! ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 

[Angel Ariel]

I'd be willing to bet you an inordinate amount of money that your lens is fine. If you play this game long enough, you can find something wrong with everything you have. Stop being obsessed with what you read in an internet thread somewhere and go enjoy your new lens. You can always spend $300-400 more and get a new one that does the same things if it makes you sleep better.

I've played the game you're playing with yourself with almost every body I've ever bought (NEW) and it almost drove me insane until I STOPPED.

Use it to take pictures of persons, places and things and not bricks in your house. It is absolutely THE best EF-S lens Canon makes and that covers some ground. Mine stays on one of my crops virtually ALL the time.

As I said, I'm not obsessing. After I took the squared shots this morning, I was no longer concerned about the decentering, as I stated in a post this afternoon. So thank you to photo chick for correcting me there, it helped a lot

I did return to the store today to test a new lens to check on the IS noise, but they didn't have any in stock. The person there (part owner I believe) also heard the noise I was hearing and also was not sure it was normal, but without having a new one to test against there wasn't much to do. He did write down that I was there about this issue today, and noted that I will be coming back when they have new lenses in stock to test ot against. If the IS noise does turn out to be a problem, I will be able to return the lens even though I will be past the 2 week no questions asked return period. So I get to keep the used lens and actually use it for real shots in the meantime, which I'm looking forward to and if thr IS is a problem, I will still be able to return it later. Win win for now.

 

[Angel Ariel]

I totally get wanting to make sure it's right. But you gotta stop pixel peeping! It's a one way trip to crazy town when you start looking at things that closely. The next thing you know you're thinking all your lenses are broken (I got to that point when I first went digital) and you're ready to chuck them all out the window. I'm saying this a little tongue in cheek, but you really can drive yourself batty examining things too closely. Humans are not machines and you will never get that camera completely square. You could use a copy stand and it would still likely be a hair off at minimum. And that will show when you're looking that closely. This is why you view the image at a "normal" size when you're doing the initial evaluation for these tests. Then if something screams at you as being off, you examine it more closely.

I've honestly never heard the term pixel peeping before. I never would ha e looked at it at 200% if it was not suggested to me here, it just wouldn't have occurred to me. I wasn't sure what I was seeing, so thought I'd come back for advice..that's all .

Any stress coming across in my posts is related to the timing issue of the return period and today being my last opportunity to get to the store before that period was up..but the store is working with me and showing awesome customer service since they didn't have a new lens to compare with, so that's no longer an issue and I'm looking very forward to enjoying this lens in the meantime

 

[Angel Ariel]

Angel, what is your reaction when you take shots of people and things around your house? The very first time I used it to shoot some random pics of Katie, my response was "wow". It was that much better than what I had ever gotten with a kit lens.

I havent had a chance to really use it. The few shots I did take took time away from other deadline things that need to happen at the moment. I should't even be online right now, lol, but I needed a quick break. It's chaos in our house tonight, and tornado warnings and massive thunderstorms complete with hail haven't helped! I'll have a better chance to play with it starting tomorrow afternoon

 

[mom2rtk]

I totally get that! More than once a new item has arrived here to remain untested at all until precariously close to the end of the return period. Just last year it was the Sigma 18-35 f/1.8. Thank goodness I bought from a reputable place (B&H) and they were kind enough to let me exchange it even though it was past the 30 day return period.

I hope life (and mother nature!) settle down for you soon and you are able to put the lens through its paces.

 

[WilsonFlyer]

These lenses make a little noise. Some more than others. ALL lenses do. Some click. Some whir. Some burp, and some holler. LOL It's normal. It's why they came out with the newer (What are they called? STM???) lenses, so everybody would run out and replace all of their perfectly good lenses with new lenses that don't keep as MUCH "noise." {sigh}

This all started over the video stuff. Wanna take video? If you're not doing cinematography, get a camcorder or use your phone. If you are creating the next Sound of Music, you probably already know how to deal with lens noise issues anyway.

Seriously. STOP IT! You are going to drive yourself crazy. You said yourself that you're not anywhere near an expert! Go enjoy your lens! With all due respect, stop trying to make it something it's not. It's a GREAT lens, BUT it's a $500 lens (used), and while it may seem to you that it ought to be gold plated, you're playing in a field here that is massive and where that lens is actually the low-hanging fruit. Canon makes hundreds of lenses. I own a large handful, and some of mine cost 5-6x more than that lens cost new. I'm not being critical. I'm just trying to make a point. Most people get the kit lens that came with their camera, buy a cheap/sub $200 "zoom" lens, and think they've done something, and never buy anything else. They don't know any better and most of them simply don't CARE. It's fine for what they want to do, but they blame bad pictures on the wrong things then because they don't know (or bother to learn) any better.

You have, by choice, placed yourself in a rather exclusive club by actually buying good GLASS and investing in your (new) hobby. Don't screw it up by obsessing with what's wrong. Obsess on which lens you're going to buy next. The 70-200 f4L or 2.8L is a GREAT next choice, and will become your "go-to" lens for almost everything that's not just "walk-around." Start worrying about that. Then you will have arrived at the first step of a very long and expensive journey. Welcome aboard!

 

[WilsonFlyer]

Now, a confession.

Would you believe, that until just now, I NEVER really read what you thought your problem was? Why? Am I that arrogant? Yea probably, but that's not why.

I've seen these threads run into the hundreds of posts on an almost DAILY basis over on POTN, Fully 99% of the time there is absolutely nothing mechanically wrong. It's almost always a problem with usage, or the technical ability of the photographer, or a lack of proper understanding of the photographer of the limitations and capabilities of their (piece of) equipment.

As I have said above, it used to bother me too. Now I still read those threads daily, but mostly for entertainment value. It's amazing to see how obsessed people get over the silliest things. What's really entertaining is to read them and know I used to be exactly the same way.

 

[Angel Ariel]

The part owner of the camera store also thought the noise he was hearing was unusual, so it isn't something I'm nitpicking. Without a new lens to compare it with, as they had none ib stock, he's essentially extending my return period and I appreciate the great customer service.

I don't expect the lens to be gold plated. I just want to make sure that the lens is working properly. If the noise is a natural part of the lens, sobeit - but can't know that until I have a new lens to compare it with. Until I have that opportunity (they won't have any new lenses in for a few weeks), I now get to use the lens and continue to test it without concerns about the return period. I plan on enjoying it this week

I don't know how else to illustrate that I'm
*not* obsessing. :

 

[photo_chick]

The part owner of the camera store also thought the noise he was hearing was unusual, so it isn't something I'm nitpicking. Without a new lens to compare it with, as they had none ib stock, he's essentially extending my return period and I appreciate the great customer service.

I don't expect the lens to be gold plated. I just want to make sure that the lens is working properly. If the noise is a natural part of the lens, sobeit - but can't know that until I have a new lens to compare it with. Until I have that opportunity (they won't have any new lenses in for a few weeks), I now get to use the lens and continue to test it without concerns about the return period. I plan on enjoying it this week

I don't know how else to illustrate that I'm
*not* obsessing. :

You did what I'd have done in your shoes, took it to someone who has more experience and can help you determine if there is something wonky or not. I hesitated buying used for a lot of years because of the type of situation you're going through now. I didn't have the knowledge necessary to really examine a lens for defects. Now we have places like KEH that offer 6 month warranties on used gear so you can buy used with a lot more confidence no matter what your skill level.

 

[havoc315]

Almost every lens has some decentering to some degree. It is usually not an issue --- In most shots, your corners will be less sharp, even in a perfectly centered lens, regardless.

Decentering is only an issue in extreme cases... If the center is blurrier than the margins. As long as your center is sharper than your corners, you're okay. Don't obsess about 1 corner being microscopically sharper than another corner.

It is never necessary to look at any image at 200%. Looking at 100% will allow you to determine whether you got critical 100% fine detail sharpness or not.. which gives you more printing and cropping latitude. But honestly, if you are viewing at normal sizes, sharing on the internet, etc... Then even 100% fine detail critical sharpness is overrated. (Though I am guilty of often pixel peeping for it myself).