16-35mm f/2.8L II possible lens blur problem

Hello there,

I've had this lens for a few years now and on a holiday last year I had accidentally dropped it on its own from my backpack. I had it inspected by Canon who only found the lenses and fittings to have come loose (glass was undamaged). They replaced some fittings and scratched casing and I started using the lens again. Recently I've taken it to another small night photography trip and noticed some uneven blur on the right side of photos. It looks significantly more blurry than the left side and wonder if this might be an issue with the fixing of the lens. The lens zooms and operates smoothly though so I'm not sure if it can mean any loose fittings. Could I get some thoughts? Lens is out of warranty.

Photos taken recently, unedited (no cropping) JPEG out of camera:

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Photos above might be a bit dark, so I attach some touched up versions of the same photos. They have been cropped slightly, but if anything, more of the right side of photos are cropped off yet there is still significantly more blur on the right of these photos.

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and for comparison, here is a photo of the night sky BEFORE I dropped/fixed the lens in 2013:

pre-drop image in 2013

What would everyone think is the cause? Should I be taking it back to Canon for a check? Thanks!

For some reason I can't get the posted images to enlarge so I can look at them closely, but this sounds like a classic case of a lens element knocked out of alignment. The 16-35 f/2.8 is already pretty soft at f/2.8 in the corners, so a misaligned element is disastrous. You can verify this problem with the newspaper on the wall test, but I'm pretty sure it needs fixing.

Good luck!

hotdog321 wrote:

For some reason I can't get the posted images to enlarge so I can look at them closely, but this sounds like a classic case of a lens element knocked out of alignment. The 16-35 f/2.8 is already pretty soft at f/2.8 in the corners, so a misaligned element is disastrous. You can verify this problem with the newspaper on the wall test, but I'm pretty sure it needs fixing.

Good luck!

Thanks, I've sent an email to Canon simultaneous to this thread given your reply.

Wonder if others are also having trouble enlarging the images?

Almost certainly an element out of alignment.

IMO if your primary interest is milkyway/nightscape photos I would call the lens a total loss and upgrade to something much better. The left side of your lens is sharper, but the coma is pretty terrible, and the corners are mostly mush even on the good side.

The Rokinon 14mm f/2.8 is a good cheap alternative. Fully manual, but wider, and less coma than the canon. Sharper in the corners but a little less sharp in the center.

The Nikon 14-24 f/2.8 would also be fully manual but it is significantly sharper in all parts of the frame, wider, and almost no coma.

The new Tamron 15-30 f/2.8 VC is about on par with the Nikon, except you gain VC, AF, a native canon mount, but lose 1mm (still a 1mm gain over the canon).

You also lose screw on filters with all of these lenses which may or may not be a deal breaker for you.

The final option is the canon 16-35 f/4. You lose a stop, but the corners are significantly sharper and you maintain the use of filters. Also gain IS on this one.

Just something to consider if you are going to end up with a $300 repair bill just to get the lens to subpar compared to newer lenses.

Landscapeforfun wrote:

Almost certainly an element out of alignment.

IMO if your primary interest is milkyway/nightscape photos I would call the lens a total loss and upgrade to something much better. The left side of your lens is sharper, but the coma is pretty terrible, and the corners are mostly mush even on the good side.

The Rokinon 14mm f/2.8 is a good cheap alternative. Fully manual, but wider, and less coma than the canon. Sharper in the corners but a little less sharp in the center.

The Nikon 14-24 f/2.8 would also be fully manual but it is significantly sharper in all parts of the frame, wider, and almost no coma.

The new Tamron 15-30 f/2.8 VC is about on par with the Nikon, except you gain VC, AF, a native canon mount, but lose 1mm (still a 1mm gain over the canon).

You also lose screw on filters with all of these lenses which may or may not be a deal breaker for you.

The final option is the canon 16-35 f/4. You lose a stop, but the corners are significantly sharper and you maintain the use of filters. Also gain IS on this one.

Just something to consider if you are going to end up with a $300 repair bill just to get the lens to subpar compared to newer lenses.

Thanks so it does look like there'll need to be a trip back to Canon then. I've really liked the lens though, and I'm the kind of person who tends to stick to the original manufacturer products. Manual wouldn't be ideal either. Tamron looks good on paper. Don't think i would consider an f/4 if I do focus on the night sky since fast shutter speed is quite key and IS is useless on a tripod. I do take it on travel too, when IS may become useful (especially in churches) but I found the lens to be sharp over past use - if it went back to its good old days then I'd be happy.

Hello,

Much apologies, was swamped with work that I had placed all my photography stuff aside and didn't come on the forum.

Basically, yes it has been solved, but pretty much by bringing it into the local Canon service centre which confirmed some of the elements were misaligned. They aligned them again but charged me for the alignment even though I had basically not used the lens since I last took it back from them from a previous service. It was 6+ months since I got it back though so they do have a point they don't know if I had just dropped it again (lol). But I knew for myself that it's been in my dry cabinet since I had gotten it back.

I still haven't really used it after they aligned it again (it's been another year?). I'll be taking it on a trip to Iceland in a couple of weeks so I could check out if they did the alignment correctly this time.

MitchAlsup wrote:

While I agree with the person above who stated that one (or more) lensing elements are out of (what astronomers call) collimation;

There might not be a lot Canon can do for you.

The other thing is that I never use a lens wide open for astro images, try stopping it down to F/4 and F/5.6 or F/8 and see if the images clean up. Also note at 24mm, a 30 second exposure will have stars on the equator move 6 pixels or so unless you use a motorized mount.

Thanks Mitch. Wonder if you may clarify the reason you say Canon might not be able to do a lot in the case of a collimation? Not sure if it was mentioned above but the lens was previously dropped on concrete once, and I was told by Canon that the lens elements misaligned after. Their first fix apparently didn't fix the problem (would this be what you speak of? i.e. that it's very difficult to completely align the lens elements out of the original factory so there will always be collimation once it happens?).

I'm not particularly seasoned at astrophotography (I just like looking at the stars and take the occasional photos of them while on holiday), but I've also only ever heard of people suggesting to use the largest aperture when taking photos of the night sky. Wonder if your suggestion of a smaller aperture is only to see if it is a lens problem or an inherent lens characteristic?

Thanks for the tip on star trail movement. I usually go for around 15 seconds, at 16mm, that should be a lot less movement? (Though again I'm not particularly well versed and don't know how much movement that will be).

I might take a few photos with a simple patterned subject over the weekend to see if there is noticeable uneven blur.

Thanks!

Thank you Mitch for your time and explanation. I'll look up MTF as you've mentioned. My knowledge on the technical side is really not that great but I'll try to understand it better.

The weekend just went by (It's Sunday night here), but I'll see if I could take something wide open during the day next week.

Cheers!

KEN KUO wrote:

HELLO,   Hiki08

I have exactly the same problem as your 16-35 lens!

did Canon fix your problem with it finally?

Yes, Canon fixed it in the end so the blur seemed even across the board 

Then the 16-35mm f/2.8L iii came out and I bit (seeing it's one of my most passionate focal lengths)