Avoiding DSLR Light Leaks

Here’s a wee tip that might be of some interest to the new photographers out there, specifically those using DSLRs.

You know when you bought your DSLR? You know how there was a neck strap in the box? You know how that strap is usually really terrible and not worth hanging onto? Well before you chuck it out take a closer look.

It’s very likely that somewhere on that ghastly piece of nylon is a rectangular piece of flexible rubber. It might look a bit like this:

Rubber Thingy

Have you ever stopped to wonder what that might be? Wonder no more. That rubber thingy is properly called an Eyepiece Cover and is designed to go over the eyepiece of your camera when you’re not looking at the viewfinder – a typical example of this might be if taking a long exposure and have stepped away from the camera to prevent blur caused by your movements.

The eyepiece slides off the viewfinder

The Eyepiece Cover in place

Why would you want to do this? Two reasons. Just as light comes through the viewfinder from the lens so you can see it, light can also enter the camera through the viewfinder. This can do two things: firstly it might affect your exposure by messing up the cameras internal metering and secondly it might cause weird light leak issues that cast strange colours or blobs into your images.

This problem only affects DSLRs as they bounce light around using mirrors – if you are using Live View (i.e. using the LCD to compose your shot) then the reflex mirror is locked up and this issue doesn’t arise, and if you’re using a Mirrorless camera it’s not a problem at all, but if you’re composing using the viewfinder with a DSLR then it may very well be an issue. Here’s the result of some of my experimentation (coz we do like to prove a point here at Pickled Light HQ):

2 Second Exposure. Lens Cover on. Viewfinder exposed to light resulting in a leak.

The above picture was a two second exposure with the lens cover on and a light shining into the viewfinder. If you look closely you can see a distinct purple blob in the top quarter of the picture, proving that light leakage can occur and could be a problem.

Those using other brands of DSLR often have more elegant means of controlling this – it seems particularly silly and a little bit cheap to use something which is so easily overlooked and/or lost but as the world moves away from DSLRs to Mirrorless the issue will go away. In the meantime, time to rummage around and see if you can find that rubber thingy coz it might just come in handy.

Check out my other articles