5D3 strange vignetting and dark LCD

[adrjork]

Hi everyone,
I've a 5D3 since a couple of years. Since last month, I noticed a big vignetting in all the new photos (never noticed before). A comparison between "old" photos made with Tamron 24-70 + filter, with new photos made with the same lens + filter, reveals evident vignetting only in the most recent photos.
What's the reason?

I started noting this issue after a backlight (landscape with sun in the frame) shooting session.

I also started noting that the camera's LCD seems darker (I have to set the brightness on max level in menu settings!)
Which is, in your opinion, the problem?
HERE are an example: 3 photos: the first 2 photos are "old" (24-70 at 35mm and 24mm) and there isn't vignatting, while the 3rd is "new" (24-70 at 36mm) revealing an evident vignetting.

Many thanks in advance for your help.

[ScottyP]

I see the same corner tip darkening in shot 2 as in shot 3. I think your filter is too thick. Possibly a lens hood in the photo problem it there is a hood.   If there is a hood try shooting without each (filter and hood) separately and then without both so you can see if it is one or the other.  They make thin filters for this kind of problem. 

[adrjork]

Hi Scotty, thanks a lot for your reply.
I don't use hood (never). But, if the problem is the filter, why in the 1st shot (24mm!) there wasn't vignetting.
And secondly, if the same corner tip darkening is visible in both shot 2 and 3, why in 3 (most recent shot) is so noticeable?

And what about the darkening of the LCD? Could be anyway related?

[ScottyP · Accepted solution]

I don’t think the LCD is a related issue. 

As as for the vignette differences it could be a factor of 1.) larger/smaller aperture and 2.) different backgrounds. 

All lenses tend tend to have more fall-off (vignetteing) around the edges at larger apertures.  I note shot 3 is indoors so the aperture may be more open. The combo of aperture vignetting plus filter obstruction may be working together to make it more noticeable in the wider aperture shot.

Also some backgrounds will show vignetting more. A white or neutral grey background like in shot 3 with no pattern probably shows it very strongly.  

[ScottyP]

Also a wide angle lens shows a filter more than a more telephoto lens does.  Shot 2 is at 24mm and shows a bit. Shot 1 is at 35 and doesn’t much. 

[Ray-uk]

To perform a proper test you need to photograph a plain surface at different focal lengths making sure that you use the same aperture for each shot. It is possible that the lens itself may vignette slightly, sometimes more at some lengths than others and different apertures will definitely give different results.

Your camera LCD display can be set into different modes and it can show a normal picture or an exposure simulation, this can effect the display brightness.

Nothing to do with your problem but a hood will do more for your pictures than a clear filter, in fact if you use any sort of filter then a hood becomes even more important.

[Tim]

Hello adrjork, 

The issue that you describe is happening to a third party item, the Tamron lens hood.  The camera itself wouldn't be related to the lens issue and should be seen as separate.  I'm not able to troubleshoot a Tamron lens however you may wish to try shooting without the filter altogether.  By leaving it on there you are likely to continue to experience issues, with this or other lenses.  

Secondly, I would recommend trying a Canon EF series lens, without the filter, on the camera to rule out the Tamron being the cause of the issue.   

[TCampbell]

Any camera lens has an "angle of view" ... an imaginary cone in which anything inside that cone would be visible in an image and anything outside the cone would not be visible in an image.

Lens hoods are usually designed to work with a specific lens (they should not be used on any other lens other than the lens for which they are intended) because the hood may interfere with that "cone" and this results in dark corners (vignetting) (and especially if you shoot wide-open).

Filters can create the same problem ... especially with wide-angle lenses.  Though a filter isn't as large as a lens hood, it is closer to the glass which means it doesn't take much for the black ring on the filter to show up in the corners of an image.

The camera itself would be fine.  This is a lens / hood / filter issue.

[adrjork]

Thank you all for your replies.

Yes, probably the LCD is a non-related issue.

About the vignetting... Tamron 24-70 at 24mm itself causes a bit of vignetting: this is what I've read in many forums and I've noticed in some other old photos I've taken.

After a quick test on a uniform white surface, I noticed that vignetting doesn't get worse with Hoya filter on the lens. Instead what causes a terrific vignetting is the Xume/Manfrotto lens adapter (which I use after the UV to eventually quickly stack NDs).

Now, why have I never clearly noticed it up to now?

Three reasons:

1. I'm stupid;

2. Light/ISO/Aperture conditions AND lens correction in Adoba Camera Raw;

3. I mainly do videos, not photos, and this means using not exactly the entire sensor but a bit smaller portion.

So in video mode, the camera "cuts out" almost all the Xume super-vignetting border.

Thank you all.