topic Re: 70-200 f/2.8L blurry at 200mm + low aperture in EF & RF Lenses

70-200 f/2.8L blurry at 200mm + low aperture

izzi — Thu, 24 Aug 2023 13:08:04 GMT

I have been using this lens with my 6D for years (admittedly not regularly - only when I travel), but have recently noticed that things get blurry (moreso toward the outer edges of the image) at 200mm with lower apertures. I can already see the blur through the viewfinder. At higher apertures, photos actually come out less blurry than what I see through the viewfinder. Here are some test images (200m, one-shot AF on the text - I've also tried MF with same results).

f/2.8:

f/8.0 - not as bad:

I'm assuming there's some sort of lens damage - perhaps moisture? Any tips to try out in the field? I won't have access to camera repair for a few months. Thanks in advance!

Re: 70-200 f/2.8L blurry at 200mm + low aperture

Peter — Thu, 24 Aug 2023 15:05:30 GMT

What if you use live view as focus method? Take a picture of something without depth. A brick wall for example.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

ebiggs1 — Thu, 24 Aug 2023 15:06:46 GMT

"Here are some test images..."

Neither of the sample shots prove anything. Keep in mind as your FL increases all imperfections increase. It is normal for 70mm to look better than 200mm. Also when you are testing your lens you must keep everything on the same plane and square to the camera/lens combo. The suggestion of a brick wall or other flat surface is good but not by itself. You still must keep the camera/lens perfectly 90 degrees form the subject wall. Otherwise the test is invalid.

Your sample shots suggest you may have been slightly to the left of the subject. And, if that was the case DOF would explain the issue. DOF, at 200mm and f2.8 and at that close of distance to subject, will be very shallow.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

izzi — Thu, 24 Aug 2023 15:36:06 GMT

Thank you both for your suggestions! Here are two more sample photos - 90 degrees to flat surface, taken with live view. I should also emphasize that this is a recent issue after years of sharper photos under same conditions (200mm in low light) with this lens + body, and that the blur is highly noticeable through the viewfinder.

f/2.8 and f/8 again:

Re: 70-200 f/2.8L blurry at 200mm + low aperture

rs-eos — Thu, 24 Aug 2023 15:53:13 GMT

As Peter mentioned earlier, it would be much better to provide images of something with no depth such as a brick wall or any wall with enough detail on it).

In the new images, even at f/8, the item in the background (left) with the recyling logo is in an out-of-focus area.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

ebiggs1 — Thu, 24 Aug 2023 15:56:12 GMT

Not wanting to beat a dead horse but you are not perpendicular to the box. You must be in order to determine anything.

"...taken with live view."

That has nothing to do with how sharp your lens is. Perhaps you have a faulty lens, it happens even to the best. You have two ways to go, send it to Canon and ask for a C&C or you can test it properly to see if it truly needs to go to Canon. You will need a tripod and a perfectly placed camera/lens to subject set up. I would also suggest you do this in good lighting conditions to avoid any focus misses.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

ebiggs1 — Thu, 24 Aug 2023 16:00:33 GMT

"As Peter mentioned earlier, it would be much better to provide images of something with no depth such as a brick wall ..."

That isn't good enough. The camera/lens has to be in perfect alignment to the wall or the test is useless. Also set on a sturdy tripod. The SS (1/160) in the test photo was also a bit slow if it was hand held.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

FMTrindade — Fri, 19 Apr 2024 23:37:17 GMT

Hello.

Sorry for reopening this but I am under the impression that either we are getting too technical or something is way out of what was indented here...

Izzy: Your lens sucks at 200mm f/2.8 Period!
Unfortunately, there is no need for a 100% perpendicular test to assess that and if everybody else is demanding that, they are just blind. Or unexperienced users.

I have the same issue with my EF 70-200 IS L USM.
It sucks at 2.8 it's fair at f/3.2 better at f/3.5, sharp at f/4.

The thing is so bad that at 200mm f/2.8 I could see a ghost and there was a pixel shifting.

I have opened the lens, went trough all elements, cleaned them up, remounted the lens trying to align everything with the help of precision measure rulers as best as I can, and the result is:
- more sharp;
- no ghost at 2.8
but still soft as hell at 2.8
3.2 is now more than acceptable at 200mm

A7 70, 100, 135 all are ok.
It is just at 200 f/2.8 that this happens and I still can't figure out why!!!
I mean, obviously the circle of confusion is way larger than the camera pixels but heck, if it happens, then I have to move the camera backwards or forward... looks like at f/2.8 the focus plane is NOT on the sensor plane.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

ebiggs1 — Sat, 20 Apr 2024 15:29:43 GMT

Us "inexperienced users" can easily see you are about 8 months late to the party which by this time is most assuredly over.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

izzi — Sun, 21 Apr 2024 08:34:39 GMT

@FMTrindade I appreciate your validating that there was clearly something wrong with the lens beyond user error, without getting too technical about the test 😂 I also appreciate everyone else's time and suggestions. Should have emphasized that my main question was not whether there was something wrong at all, but whether anyone had tips for (temporary) fixes in the field.

In case it's helpful to anyone with a similar issue - a heated dry box helped reduce the blur a little, but not for long. I eventually brought the lens in for repair. It did indeed have a busted element, probably from an unlucky knock, which required the whole group to be replaced.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

FMTrindade — Sun, 21 Apr 2024 11:18:54 GMT

Hi.

If a Heated dry box helped a bit, most likely you had humidity and/or fungus.

Glad you could make it work.

There is always a way to make a quick test:

The front element is usually the focus fine tuner. And if it is tilted or disaligned, then the image will never get ok.

So, first thing, besides checking the lens for extreme dust and fog at the elements at the sensor/camera side is to test the last element on the outer side of the lens (the side pointing towards the motif).

Usually there is a way to get to this element without disassembling the whole lens.

Then, you will find 3 or 5 screws. Two to fix the lens, three to act as guides in an heliconcentric set of rails.

With the camera on, and connected to a big screen via hdmi, test and align the correct placement of the last element until it gets as sharp as possible. Check for the boqueh in out of focus areas. It must be circular, not skewed or oval.

Align the best you can. If at the best it is still bad, then the disalignment is on the zoom/focus block and it will need a professional fix (or from some curious **bleep** like me) to solve it, or a replacement of the part.

Usually dust and scratches on the far side lenses do not affect IQ much (to a point, of course). Only those on the sensor side will.

Usually the problems on the far side do affect alignment and focus.

Cheers.

Live long and prosper!

Re: 70-200 f/2.8L blurry at 200mm + low aperture

Waddizzle — Sun, 21 Apr 2024 11:44:25 GMT

@izzi wrote:
I have been using this lens with my 6D for years (admittedly not regularly - only when I travel), but have recently noticed that things get blurry (moreso toward the outer edges of the image) at 200mm with lower apertures. I can already see the blur through the viewfinder. At higher apertures, photos actually come out less blurry than what I see through the viewfinder. Here are some test images (200m, one-shot AF on the text - I've also tried MF with same results).
f/2.8:
f/8.0 - not as bad:
I'm assuming there's some sort of lens damage - perhaps moisture? Any tips to try out in the field? I won't have access to camera repair for a few months. Thanks in advance!

Welcome back to the Canon Forums!

You have not provided sufficient information to fully diagnose your issue. You have not provided exposure settings, specifically shutter speeds. You were asked indirectly when it was requested that you post an original image for evaluation. I assume your posted images have had the EXIF data scrubbed away. Please post your exposure settings, or include the EXIF data.

Did you have IS enabled? Are you using any lens filters? What were the switch setting on the lens? Did you take your Live View test shot using a tripod?

Testing your gear is just as much a test of the photographers as it is the gear, if not more so.

Thanks, ahead of time.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

Waddizzle — Sun, 21 Apr 2024 11:51:29 GMT

“ That has nothing to do with how sharp your lens is. Perhaps you have a faulty lens, it happens even to the best. You have two ways to go, send it to Canon and ask for a C&C or you can test it properly to see if it truly needs to go to Canon. “

Testing your gear is just as much a test of the photographer as it is the gear, if not more so.

Re: 70-200 f/2.8L blurry at 200mm + low aperture

Waddizzle — Sun, 21 Apr 2024 11:59:58 GMT

“ In case it's helpful to anyone with a similar issue - a heated dry box helped reduce the blur a little, but not for long. I eventually brought the lens in for repair. It did indeed have a busted element, probably from an unlucky knock, which required the whole group to be replaced. “

I just noticed this post. Thanks, for the follow up. I’m pleased that you found a solution.