topic Re: Canon 70-200 - focal plane loss in EF & RF Lenses

Canon 70-200 - focal plane loss

JazzJ — Fri, 15 Jan 2021 10:59:32 GMT

Hi all,

Hoping someone can give me some advice. I am shooting on a Canon M50 with a Canon 70-200mm f2.8 IS USM II. Recently, I have been noticing a loss of focus/ some soft areas in my images. I can't decide whether it occurs at a certain aperture or focal length, or if it's just something very weird. See below the images as an example.

You can see the surfer taking off on the wave is sharp, but the surfer on the right hand side is soft. Basically, from that position in the frame, it's all soft. Almost 1/4 of my frame. It doesn't bother me too much, but it's something that I just can't wrap my head around.

Any advice welcome.

TIA

Re: Canon 70-200 - focal plane loss

Waddizzle — Fri, 15 Jan 2021 13:55:40 GMT

I had not noticed the surfers. Depending on your aperture setting, it is possible for only one to be within the DOF.

The plane of perfect focus is not flat, either.

Re: Canon 70-200 - focal plane loss

ebiggs1 — Fri, 15 Jan 2021 14:36:04 GMT

"I had not noticed the surfers."

Me either! I don't think DOF is the problem but a middle of the road quality jpg probably is. Next time try a full image Raw and do lens correction in your LR with some small amount of sharpening.

Every time you save a jpg you lose IQ. It doesn't matter if you do anything to it or not. This does not happen to Raw. Another issue is as distance increases, IQ decreases. In other words closer is better and it is a lot better.

Re: Canon 70-200 - focal plane loss

jrhoffman75 — Fri, 15 Jan 2021 14:51:52 GMT

@ebiggs1 wrote:
"I had not noticed the surfers."

Me either! I don't think DOF is the problem but a middle of the road quality jpg probably is. Next time try a full image Raw and do lens correction in your LR with some small amount of sharpening.
Every time you save a jpg you lose IQ. It doesn't matter if you do anything to it or not. This does not happen to Raw. Another issue is as distance increases, IQ decreases. In other words closer is better and it is a lot better.

I agree it's not a DOF issue, but I don't think its a JPEG issue.

You can see the image get progressively worse as the you approach the edge of the frame.

Find a brick wall if you can. Set the camera on a tripod. Be sure camera is perpendicular to the wall. Set the aperture to f/8 and take an image.

Almost looks like the lens needs to be checked. That lens should be razor sharp.

Re: Canon 70-200 - focal plane loss

JazzJ — Fri, 15 Jan 2021 14:56:50 GMT

Thanks all. I only shoot RAW and export to jpeg. Perhaps a smudge/ blemish on some internal glass of the lens?

I agree, it should be pin sharp. I will check again using the flat wall and see.

Any advice if it's still blury? Take it in to a camera store?

Re: Canon 70-200 - focal plane loss

ebiggs1 — Fri, 15 Jan 2021 14:58:43 GMT

John I agree. But a reduced jpg quality doesn't help.

I do think the lens needs to be looked at. Can't hurt and might just help!

Re: Canon 70-200 - focal plane loss

ebiggs1 — Fri, 15 Jan 2021 15:00:56 GMT

"Take it in to a camera store?"

No! A lens like that needs to go to Canon. Ask them to do a C&C.

Re: Canon 70-200 - focal plane loss

jrhoffman75 — Fri, 15 Jan 2021 15:09:03 GMT

@ebiggs1 wrote:
"Take it in to a camera store?"

No! A lens like that needs to go to Canon. Ask them to do a C&C.

Absolutely send to Canon. And include a copy of your image. So they can see exactly what the problem is.

Re: Canon 70-200 - focal plane loss

JazzJ — Fri, 15 Jan 2021 15:23:03 GMT

Just contact Canon here in Portugal. Thank you all.

As a reference, I have attached here the CR3 file if anyone would like a closer inspection.

https://drive.google.com/file/d/1jpu0k-2igq48oa6xR6EUZ640hAd6rUiP/view?usp=sharing

Re: Canon 70-200 - focal plane loss

JazzJ — Fri, 15 Jan 2021 15:26:18 GMT

And to throw yet another spanner in the works. Same day (maybe 15minutes apart), same lens, same body. Sharp.

Re: Canon 70-200 - focal plane loss

jrhoffman75 — Fri, 15 Jan 2021 15:50:59 GMT

@JazzJ wrote:
And to throw yet another spanner in the works. Same day (maybe 15minutes apart), same lens, same body. Sharp.

That perhaps changes things.

Which image was first - the good or the bad? Did maybe some water splash on the lens?

Re: Canon 70-200 - focal plane loss

rs-eos — Fri, 15 Jan 2021 16:12:38 GMT

In looking at the first image, it appears soft all around and only sharp in the center.

e.g. if looking at the upper-most wave in the image (with the surfers) from left to right... it starts off soft, then the mist, water and middle surfer are sharp, but then softens as you move to the right.

Same for the breaking wave about 1/3 from the bottom. Starts soft, then gets sharp near the middle, then soft again.

Since there's a decent distance from this breaking wave to the middle surfer, and the mist behind the middle surfer also being quite crisp, the DOF would have been large enough for the other surfer and other parts of those waves.

As mentioned earlier, try taking an image of a brick wall or some vertical surface with enough detail. Have the lens be as perpendicular to the vertical surface as possible. Try different apertures; When wide open, lenses can exhibit softness near corners/edges, though I wouldn't think it would be this extreme on such a lens as yours.

Re: Canon 70-200 - focal plane loss

jrhoffman75 — Fri, 15 Jan 2021 16:21:17 GMT

Here's the two surfers in a screenshot from DPP and the downloaded .CR3 file.

Re: Canon 70-200 - focal plane loss

JazzJ — Fri, 15 Jan 2021 17:07:35 GMT

The sharper one was taken first, but no water got on the lens. And inbetween there are sharp images and some with the same focal/ softness. I actually first noticed the softness last June on another surf trip.

Could it be to do with maybe the camera's AF settings? Just thinking out loud.

Re: Canon 70-200 - focal plane loss

JazzJ — Fri, 15 Jan 2021 17:08:55 GMT

Exactly. It's almost as if it's vingetted, but with sharpness (if that makes sense).

I will do the brick wall test. Should be able to do it tomorrow and hopefully see something. I will try at different apertures as well as different focal lengths.

Re: Canon 70-200 - focal plane loss

ebiggs1 — Fri, 15 Jan 2021 17:10:41 GMT

"Did maybe some water splash on the lens?"

You may have something there. I loaded the Raw file into PS and enlarged it drastically. None of the image is really sharp. It is as if the SS was very slow. Star trails kinda stuff although exif says 1/4000. I don't think there is anything wrong with the lens. Something outside happened. I know it might be unlikely but camera motion?

Re: Canon 70-200 - focal plane loss

JazzJ — Fri, 15 Jan 2021 17:12:46 GMT

Maybe my IS is playing up and messing me around?

Re: Canon 70-200 - focal plane loss

Waddizzle — Fri, 15 Jan 2021 17:20:22 GMT

According to the screen shots you are using One Shot AF.

Re: Canon 70-200 - focal plane loss

kvbarkley — Fri, 15 Jan 2021 17:51:20 GMT

Time for the newspaper test

http://www.bobatkins.com/photography/technical/lens_misalignment.html

Re: Canon 70-200 - focal plane loss

JazzJ — Sun, 24 Jan 2021 13:41:39 GMT

Hi all,

Managed to do more research and finally tested with decent light and in a controlled environment. I suspect a decentered element.

Anyway, below are some images cropped to the bottom right where the issues/ softness occurs, at different focal lengths and apertures.

Noticeable clarity is lost af2.8 on edge of the frame, after f8 it seems to negligeable. I have contacted an authorised canon centre here now too, but with Covid restrictions, I'm not sure it will be repaired anytime soon. But atleast I may have found a work around for the time being.

Thank you to you all for your input and time. Feel free to offer any further suggestions if you have.