Strange circular rings on Focusing Screen - 5Dmiii

[_RD]

Hi Everyone

I recently purchased a second hand 5Diii. It appears to be in absolute mint condition. The only thing I find strange is, when I look through my VF, there appear to be very thin black circles across the whole VF.

I have tried using a blower to clean the VF, which made no difference. When I take the lens off and I look within the camera, I can notice these lines on what I believe to be the focus screen. Can anyone shed any light as to what these marks are?

For the record;

- The lines do not seem to affect the images being taken, and don't show up in Live View Mode

- The lines can be seen when there is a lens attached, and when there is not a lens attached

- The lines are of course far more obvious when shooting in high light. But definitely noticeable no matter the situation.

- The circular lines are sperated from one another perfectly (same space between each one, which suggests they are supposed to be there..)

- I am also not referring to the focus ring that you are supposed to see in the VF. These lines start from the centre and go all the way to the edge.

- One section of the black lines seems to be ever so slightly thicker than all the others, which suggests dirt maybe?

I've attached images so you can see what I mean.

Thanks in advance!

[Waddizzle]

That sort of looks like a manual focusing screen.  

Except, I am not aware of one made by Canon for that camera.

[_RD]

The photo I included was taken with the camera turned off, so none of the usual focus metering displays are shown. These of course do display when the camera is on.

But these black lines stay there constantly. They also go in and out of focus when I adjust the focus of the VF, which to me is a clear indication that this circular pattern in embedded within either the focus screen or some other form of glass that's located near it.

[Waddizzle]

---

@_RD wrote:

The photo I included was taken with the camera turned off, so none of the usual focus metering displays are shown. These of course do display when the camera is on.

But these black lines stay there constantly. They also go in and out of focus when I adjust the focus of the VF, which to me is a clear indication that this circular pattern in embedded within either the focus screen or some other form of glass that's located near it.

---

Go into the camera menus, find the setting that resets the camera back to Factory Defaults.  

I have a pretty good idea what it is that you are seeing.  If you have not downloaded a copy of the full Instruction Manual from Canon Support, then I suggest that you do so.  Make it your newest best friend.

[_RD]

I have factory resetted as you advised and still seeing the marks. 

If you have a pretty good idea of what it is i'm seeing, then it would be most helpful if you could share that information!

Thanks

[Waddizzle]

---

@_RD wrote:

I have factory resetted as you advised and still seeing the marks. 

If you have a pretty good idea of what it is i'm seeing, then it would be most helpful if you could share that information!

Thanks

---

Grid ines.  it would be more helpful if you downloaded the instruction manual and educated yourself about the camera.

[_RD]

As much I appreciate your attempts to aid me, but do you really think i'd waste my time creating this account to ask this kind of question if I didn't know what grid lines where?! I have been using Canon cameras for over 7 years and am accustomed to many variations of VF styles. But as I said in my very first message, I am not referring to the focus ring, or indeed any grid lines. These marks are irregular in width - which suggest some kind of dirt trap, and are evidently seen on the actual focus screen itself (when looking up into the inside of the camera). I can assure you these are not grid lines. I also own a downloaded copy of the instruction manual, where I found no reference to these lines - hence why i'm here!

Best.

[Waddizzle]

---

@_RD wrote:

As much I appreciate your attempts to aid me, but do you really think i'd waste my time creating this account to ask this kind of question if I didn't know what grid lines where?! I have been using Canon cameras for over 7 years and am accustomed to many variations of VF styles. But as I said in my very first message, I am not referring to the focus ring, or indeed any grid lines. These marks are irregular in width - which suggest some kind of dirt trap, and are evidently seen on the actual focus screen itself (when looking up into the inside of the camera). I can assure you these are not grid lines. I also own a downloaded copy of the instruction manual, where I found no reference to these lines - hence why i'm here!

Best.

---

Actually, just the opposite.  If someone didn't know what grid lines were, then I expect that type of person to ask about what they are.  I suggest that you contact Canon Support, and send your camera in for an inspection.

[jrhoffman75]

The 5D Mark III does not have "user replaceable" focus screen, like the Mark II and other cameras where a little clip is dpressed and optional screens are installed.

There are no optional Canon screens; the system map in the manual shows no optional screens, where as the ID X does, for example.

There are third party screens available from eBay; none that I saw showed rings like you are describing. I agree that you should consider sending it in for Canon service.

[Ray-uk]

A lot of focus screens consist of a suface which is actually a fresnel lens which has very fine circular lines engraved, these are not normally visible unless they get dirty. It is likely that this is engraved on the upper side of the screen so it is not possible to blow any dust or dirt off without removing the screen.

As the screen of your camera is user-changeable I would suggest you drop it out (wear a pair of cotton gloves because they are easily damaged) then you will be able to see if it has a problem. A dirty screen can be washed in a dish of tepid distilled water with a drop of dish soap added, dab it dry with a tissue but do not rub the surfaces with anything.