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Gear & Apps

Purpose Behind ‘That Rubber Thing’ On Your Canon Camera Strap

By Shivani Reddy on August 25th 2016

It might be time to fish out your original Canon camera straps from that dusty manufacturers box, especially for travel and landscape photographers. I know that most photographers usually buy a 2nd or 3rd party camera strap to displace the use of the black & red craftsmanship from Canon, but this trick might prove helpful to you.


The small rectangle of rubber was actually included as part of the strap to thwart light from entering into the viewfinder. In collaboration with DIY Photography, photographer Bassam Sabbagh displays its use in a short video.


Straight from the Canon 80D manual, we find that the “rubber thingy” that Bassam refers to is an eyepiece devised to keep stray light from entering “when using self-timer, bulb exposure, or a remote switch.” The stray light that leaks through can cause the picture to look dark and therefore the rubber rectangle of magic is meant to act as a wall to block light from seeping in.


Although light leaks through the optical viewfinder isn’t a common occurrence, for time-lapses and long exposures it can be a precautionary measure for low light conditions. It is important to note that “Prism above the mirror that’s used to redirect the image” makes it possible for light to leak through, even though the mirror retracts up when a photo is taken (DigitalTrends).

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Shivani wants to live in a world where laughter is the cure to pretty much everything. Since she can’t claim “Serial Bingewatcher” as an occupation, she’ll settle for wedding/portrait photographer at Lin and Jirsa & marketing coordinator here at SLR Lounge. For those rare moments when you won’t find a camera in her hand, she will be dancing, eating a donut, or most likely watching Seinfeld.

Follow her on Instagram: @shivalry_inc

Q&A Discussions

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  1. Ralph Hightower

    My Canon A-1 and New F-1 have a lever by the eyepiece that closes a blind behind the eyepiece. But I did transfer that thingy from my Canon provided strap to a padded neck strap.

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  2. Daeshawn Ballard

    I had no idea haha.

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  3. Niklas Möller

    Why is it that every photo website is currently sharing that video in the last couple of days/weeks? :-D

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  4. Dave Norwood

    How is it that SLR Lounge didn’t know what that was for?

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    • Niklas Möller

      It’s not about if they knew. It’s about if there probably are some readers who didn’t knew and probably there are… but maybe not anymore now that (I guess) every photography website in my feed reader wrote about this :-D

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  5. Daniel Lee

    Funny how such a small thing like that could be overlooked, I never knew.

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  6. Matthew Saville

    Hot tip: Nikons come with the same accessory. :-)

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  7. Anders Madsen

    “The stray light that leaks through can cause the picture to look dark”

    Well, that is one way of putting it, I guess. :)

    If I remember correctly, the manual for my old 30D states that the stray light from the viewfinder can affect the light meter in the camera, which is why the image may end up looking dark.

    The meter thinks that there is more light than there actually is, and will cause the camera to underexpose. If you expose manually after taking a reading with your eye to the viewfinder, the problem should not occur, even if you don’t use the rubber cover.

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  8. adam sanford

    This is Canon tripod 101, but I guess it’s PSA worthy in this just-grab-stuff-and-do-it age.

    All Canon SLRs other than the 1-series don’t have a viewfinder cover, so you use the handy dandy rubber dealio to slide over your eyepiece mount. Easy peasy.

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    • Matthew Saville

      Or, for those of us who never even get the stock strap out of the box, …a bit of gaffers tape on your tripod leg does the trick when you need to black out your viewfinder in a pinch.

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    • adam sanford

      ^^^ This guy. ^^^


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