Blocking unwanted light from entering the viewfinder: Legitimate concern?

[HEA-45]

I have seen several articles recently about blocking unwanted light from entering the viewfinder of a DSLR. This light may affect the final image during long exposures. This is the first I have heard about this "concern." At first I thought it was just a tweak, but the recent rental of a Nikon D810 revealed a mechanical switch just for this function. So, is this a legitimate concern?

 

[leno]

I have seen several articles recently about blocking unwanted light from entering the viewfinder of a DSLR. This light may affect the final image during long exposures. This is the first I have heard about this "concern." At first I thought it was just a tweak, but the recent rental of a Nikon D810 revealed a mechanical switch just for this function. So, is this a legitimate concern?

Correctly it will not affect the final image, it will affect the metering. This is the same for any SLR and why they come with caps and things to block the light. However the effect depends on the environment.

 

[More Keepers]

I have seen several articles recently about blocking unwanted light from entering the viewfinder of a DSLR. This light may affect the final image during long exposures. This is the first I have heard about this "concern." At first I thought it was just a tweak, but the recent rental of a Nikon D810 revealed a mechanical switch just for this function. So, is this a legitimate concern?

Bright light entering the viewfinder can affect the light meter reading and change the exposure. It's always a good idea to block the viewfinder when the viewfinder isn't up to your face. Your experience may vary depending on the camera.

 

[Gerald in Texas]

There are two issues, fogging the image and corrupting the meter. The fact that published tests show it harmless and others harmful suggests it may vary with cameras. It's easy to test. Leave the lens cap on and make a long exposure while shining a light at the viewfinder eyepiece. If you can't make it happen, one less thing to worry about.

BUT - you have to test both for the image and for your metering.

 

[Guidenet]

I have seen several articles recently about blocking unwanted light from entering the viewfinder of a DSLR. This light may affect the final image during long exposures. This is the first I have heard about this "concern." At first I thought it was just a tweak, but the recent rental of a Nikon D810 revealed a mechanical switch just for this function. So, is this a legitimate concern?

I rarely do long exposure so don't have a lot of experience with this, but over the years, I've always thought it a good idea to block the viewfinder. Some of my cameras have that switch and some don't. The few times I've used a camera to take this kind of shot, I've always placed a handkerchief or something over the viewfinder. I've always lost those little black plastic pieces they provide to slip in there. Some probably don't even know their purpose. I keep meaning to buy one and stick it somewhere in my bags, but have never gotten around to it. They ought to provide a little storage area, maybe in the battery chamber, to store that plastic thingie.

Even my old F3hp had that little switch. I wish they all did.

 

[soufiej]

I have seen several articles recently about blocking unwanted light from entering the viewfinder of a DSLR. This light may affect the final image during long exposures. This is the first I have heard about this "concern." At first I thought it was just a tweak, but the recent rental of a Nikon D810 revealed a mechanical switch just for this function. So, is this a legitimate concern?

A "legitimate" concern?

OK, what isn't a legitimate concern if you want to think it is? A meteor could kill you while you are sitting somewhere, probably inside a building, reading this response. If you want to think that's a legitimate concern, well, ...

Me? I'm more concerned about why all the popcorn doesn't pop.

 

[BBbuilder467]

When you do a lot of outdoor long exposures in daylight, you'll want to eliminate any possibility of light leaks, flares, reflections and color casts that creep into a long exposure that you would never see at normal shutter speeds.

You'll try to eliminate anything you have physical control over to concentrate on the image itself. There are enough problems to deal with. Covering the viewfinder is the least of them. Just do it.

 

[Mike_PEAT]

Correctly it will not affect the final image, it will affect the metering.

Actually there isn't a tight seal around the mirror and light can leak into the mirror box.

Try locking the mirror up and shining a light into the viewfinder.

 

[leno]

Correctly it will not affect the final image, it will affect the metering.

Actually there isn't a tight seal around the mirror and light can leak into the mirror box.

Try locking the mirror up and shining a light into the viewfinder.

Life is too short

 

[Glen Barrington]

Generally, listen to the end user chatter about the camera you are concerned about. You will quickly get an idea of just how important this issue is, overall for that camera. If the Mfr provides one of those little OVF covers, use them. And a little cardboard cover is easy to make and certainly won't hurt anything if you use it.

 

[newmikey]

1. Normal image but with a bright sun behind the photographer. Light entering the viewfinder may confuse the exposure calculations

2. Extreme long exposure with for instance 10-stops ND (Big Stopper). Light entering the viewfinder may cause purple streaks in the image.

I use a little plastic cap which slides over the viewfinder eyepiece.