# Blocking The Viewfinder in a Long Exposure



## Old Sarge (Jul 5, 2013)

I was reading an article in a photo magazine and came across a tip I have seen before and wondered about its importance or usefulness. The recommendation was to close off the viewfinder when making a long exposure. As I considered that tip I remembered that Canon used to include a viewfinder cover which could be attached to the neck strap. In fact, I seem to recall that my F-1 had a switch which would close the viewfinder. But as I considered the necessity of using such an item I wondered if the mirror/body seal was so loose to allow light-leaks.

I rarely, if ever, take exposures of more than a second or two so I wondered if anyone who makes truly long exposures, say thirty seconds plus, has had an issue with light-leaks from the viewfinder? 

I also seem to remember, back in the early days of light meters being part of the camera, that the measurement for light value was made in the pentaprism so the recommendation was to not allow any light to enter from the viewfinder side lest the exposure be skewed. Just some random thoughts on this early morning.


----------



## The Bad Duck (Jul 5, 2013)

I seldom do exposures that long, but I do know that Canon still include a piece of rubber to cover the viewfinder. It´s on the camera strap.

Oh the good old days of light metering in the centre of the frame and in the bottom left corner (AE-1). I still think I´m spoiled when I use my 5D´s, or my old 30D for that matter.


----------



## AmbientLight (Jul 5, 2013)

It is all still the same. Most camera bodies come with a rubber cover, others with a switch like on your F-1.


----------



## cervantes (Jul 5, 2013)

I make long exposures quite frequently (30s - 60s exposure time) and I never use the viewfinder cover. I can't see any negative impact on the final image.
However if you have a bright light source behind you (eg. streetlamp) it could make a difference but if you can't read the top display of your camera without turning on the illumination it surely doesn't matter.

This image has an exposure time of 63s and I didn't use the viewfinder cover:


----------



## killswitch (Jul 5, 2013)

During the actual shoot, I often forget to cover the VF. I did not notice any significant change in the outcome of a shot with or without the cover on the VF. Maybe I was lucky to get away with it as I remember I never had any significant light source coming from behind the camera. Maybe I have not yet faced a scenario where you will need to cover the VF to get proper reading.


----------



## neuroanatomist (Jul 5, 2013)

There's no need to cover the VF during an exposure (long or short) - the flipped-up mirror means no light from the VF reaches the sensor (assuming your camera isn't defective). But if you're not blocking the light with your eye at the VF during metering, light entering the VF can affect the metering, leading to an incorrectly exposed shot. 

Current EOS bodies do come with that little rubber eyepiece cover that attaches to the strap, and you remove the eyecup to use it. The 1-series bodies have a built-in VF shutter (a little lever behind the eyecup) which is a handy feature. Before getting the 1D X, I'd usually just hang the lens cap from the eyecup instead of using the little rubber cover.


----------



## Ellen Schmidtee (Jul 5, 2013)

Old Sarge said:


> I was reading an article in a photo magazine and came across a tip I have seen before and wondered about its importance or usefulness. The recommendation was to close off the viewfinder when making a long exposure. As I considered that tip I remembered that Canon used to include a viewfinder cover which could be attached to the neck strap.



Canon includes viewfinder cover attached to the neck strap with the 5Dmk2 & mk3. I'd be surprised if xxD & xxxD models didn't have one as well.


----------



## Marsu42 (Jul 5, 2013)

neuroanatomist said:


> But if you're not blocking the light with your eye at the VF during metering, light entering the VF can affect the metering, leading to an incorrectly exposed shot.



That's interesting (and makes sense) - do you know how often that happens and how severe the impact is? I sometimes "blind meter" tripod shows w/o my eye on the vf after already having mf'ed and when not wanting to engage live-view either to save battery or to avoid distraction by the lit screen. Maybe I should start putting my finger in front of the vf when metering?


----------



## ahab1372 (Jul 5, 2013)

Ellen Schmidtee said:


> Canon includes viewfinder cover attached to the neck strap with the 5Dmk2 & mk3. I'd be surprised if xxD & xxxD models didn't have one as well.


They do. It is just inconvenient to detach the eyecup first, and then try not to loose it


----------



## neuroanatomist (Jul 5, 2013)

Marsu42 said:


> neuroanatomist said:
> 
> 
> > But if you're not blocking the light with your eye at the VF during metering, light entering the VF can affect the metering, leading to an incorrectly exposed shot.
> ...



It depends on how much light is shining on the back of the camera relative to the brightness of the scene. An effect of a stop or more is not uncommon. 

Easy to demonstrate with an extreme situation - I just turned on my camera with the lens cap on, and closing the VF shutter dropped the metered exposure by 8.33 stops.


----------



## PureAmateur (Jul 5, 2013)

ahab1372 said:


> Ellen Schmidtee said:
> 
> 
> > Canon includes viewfinder cover attached to the neck strap with the 5Dmk2 & mk3. I'd be surprised if xxD & xxxD models didn't have one as well.
> ...



In fact, there are so many people crying Canon for upgrading sensor technology and other stuffs, but not sure why not many voices to ask Canon to improve such low-hanging-fruit items.

Built-in VF shutter is the first one in my list

The others are:


Change the flat strap mount back to rings like those in AE-1, this will make my strap last longer
Include a monitor cover
Hot shoe cover

I believe that Nikon has already done those.


----------



## AmbientLight (Jul 5, 2013)

neuroanatomist said:


> Easy to demonstrate with an extreme situation - I just turned on my camera with the lens cap on, and closing the VF shutter dropped the metered exposure by 8.33 stops.



There was a time when we would almost instantly read praises of the DR advantages of another system in such rear lens cap shots . Thankfully this time has passed ;D.


----------



## shutterwideshut (Jul 5, 2013)

Old Sarge said:


> I rarely, if ever, take exposures of more than a second or two so I wondered if anyone who makes truly long exposures, say thirty seconds plus, has had an issue with light-leaks from the viewfinder?



I frequently shoot ultra long exposures (between 120s & 240s) at high noon with a 5D3+17-40mm f/4L+Hoya R72 filter combo and I do encounter light leaks whenever I forget to cover the viewfinder. To me, it boils down to the light intensity behind your camera.


----------



## Mt Spokane Photography (Jul 5, 2013)

Even a short exposure can be off if you let a lot of light enter the viewfinder while setting the exposure. A shutter would be a welcome addition. 

Those who use live view to take shots in bright ambient light are affected, FoCal warns you to cover the eyepiece while running the AFMA tests as well.


----------



## fugu82 (Jul 5, 2013)

I use gaffer tape to cover the eyepiece. The Canon rubber cover thingy gets popped out sometimes by the weight of my strap, and anyway I'm afraid I'll lose the eyecup. 
An eyepiece shutter would be great, tho; haven't had one of those since the T90.


----------



## neuroanatomist (Jul 5, 2013)

Mt Spokane Photography said:


> Those who use live view to take shots in bright ambient light are affected



With Live View, the mirror is up and metering is performed with the CMOS image sensor. Covering the viewfinder should not make any difference.


----------



## Mt Spokane Photography (Jul 5, 2013)

neuroanatomist said:


> Mt Spokane Photography said:
> 
> 
> > Those who use live view to take shots in bright ambient light are affected
> ...


 
What I was intending to say was when you have the camera on a tripod and don't have your eye to the shutter, it can affect even a normal exposure if you are in bright light.

I'm not sure how I managed to work liveview in there, crosslink in the brain. I need to send it in for a overhaul.


----------



## Hannes (Jul 5, 2013)

Ellen Schmidtee said:


> Old Sarge said:
> 
> 
> > I was reading an article in a photo magazine and came across a tip I have seen before and wondered about its importance or usefulness. The recommendation was to close off the viewfinder when making a long exposure. As I considered that tip I remembered that Canon used to include a viewfinder cover which could be attached to the neck strap.
> ...



Even my 300V came with one on the strap, I know because it is my favourite strap. It only says Canon Eos on it and it doesn't have the rubber bit on the back like the new straps so it is much easier to swing round when carried on one shoulder like I usually do.


----------

