topic View finder cap in EOS DSLR & Mirrorless Cameras

View finder cap

Ramsden — Sun, 06 Sep 2026 20:46:01 GMT

When I bought my EOS90D it arrived with a small strap with a view finder rubber cap attached. I thought this was just for protection, and fitted an eye piece and a better strap (or two).

Only today I read that the cap is to prevent light leaking into the camera and interfering with exposure.

So my question is, do you guys regularly use these caps and what are the benefits?

Ramsden

Re: View finder cap

March411 — Sun, 06 Sep 2026 21:03:47 GMT

Hey Ramsden, not only do I use them on each camera I upgraded them to give me a better seal and fit. The Canon is OK but there are several soft silicone ones that are in my opinion better.

March411_0-1788728545769.png

Re: View finder cap

Ramsden — Sun, 06 Sep 2026 21:13:04 GMT

Hi Marc

Thanks for your prompt response. I'll check these out over here.

Ramsden

Re: View finder cap

kvbarkley — Sun, 06 Sep 2026 22:57:15 GMT

That is not what he is talking about. He means the cover that replaces the eyecup when you are not at the camera, like on a tripod. Pentamirrors can leak light back to the exposure chip.

Re: View finder cap

March411 — Sun, 06 Sep 2026 23:05:33 GMT

Interesting, thanks for the heads up @kvbarkley. I have never purchased a body that had any supplied cap or type of cover over the EVF/eye piece as Ramsden mentioned and I purchased most of my bodies including my 90D new. Learn something new every day.....

Re: View finder cap

Waddizzle — Sun, 06 Sep 2026 23:56:25 GMT

“ That is not what he is talking about. He means the cover that replaces the eyecup when you are not at the camera, like on a tripod. Pentamirrors can leak. “

Correct! Your face is not there to block light from entering the OVF.

This diagram below shows where the metering sensor is located at the top of the viewfinder in a SLR or DSLR. Number 7 is the pentaprism. The metering sensor is located on the right side, where the vertical light path is reflected towards the left.

IMG_1864.png

IMG_6198.jpeg

The cover is most useful when shooting in Live View, depending upon your shutter mode. The default Live View shutter mode drops the mirror and uses the metering sensor. You need to cover the OVF.

Or, you can have mirror remain raised, and use the image sensor for metering. No cover needed.

Re: View finder cap

stevet1 — Mon, 07 Sep 2026 01:09:11 GMT

Ramsden,

These are most useful in Long Exposure photography.

If you've got a baseball cap, you can accomplish the same thing by draping it over the top of your camera, if it's not too windy.

When you bought your camera, did it come with a camera bag? Sometimes Canon will also provide a rain cover for your camera and stick it in the pouch of your camera bag. I didn't realize mine had one for like two years. If a camera bag came with your camera, check the pouch. Those rain covers will accomplish the same thing as your eyepiece cover.

Steve Thomas

Re: View finder cap

Ramsden — Mon, 07 Sep 2026 06:07:41 GMT

Thanks guys

I have reattached the small strap and cover and it will get used on a regular basis. But I can envisage quite a few eyecaps going missing on my daily meanders.

I'm just annoyed at myself for not knowing the correct purpose when I bought the camera, new.

Ramsden

Re: View finder cap

Ramsden — Mon, 07 Sep 2026 06:40:29 GMT

Thanks, Waddizle, for the very helpful diagram.

I'm currently working on using zones, so need an an accurate reading. My exposure meter is a critical part of that procedure.

I consider this a step forward.

Ramsden

Re: View finder cap

ebiggs1 — Mon, 07 Sep 2026 14:58:25 GMT

"... do you guys regularly use these caps and what are the benefits?"

No.

I have no idea where any of them are and I must have a boat load of them somewhere around here. I would hate to try and find any of them if they still exist.

Re: View finder cap

Ramsden — Mon, 07 Sep 2026 15:30:12 GMT

According to my EOS90D user guide, it says 'Cover the view finder to prevent light from seeping into the camera and affecting exposure'

It goes on to explain that the camera ships with a cover for this purpose.

1000078625.jpg

First day on, so I'll check this out and see if my zone project photography improves.

Ramsden

Re: View finder cap

Waddizzle — Mon, 07 Sep 2026 16:51:27 GMT

“ Thanks, Waddizle, for the very helpful diagram. “

I don’t know where my original caps are, either. I don’t have a need for them. The caps are only needed when the camera is controlling one or more legs of the exposure triangle.

i typically shoot in M mode with ISO auto. If I neeed to use an OVF cap, then I will put my face on the OVF and read the ISO. I will then dial in the ISO and take the shot. This is what I do for most landscape shots and longer exposures.