Covering the Viewfinder

MileHighAko

My Nikon cameras came with a little plastic viewfinder cover. The manual says that if you're taking photos without your eye up to the viewfinder, you should remove the rubber and cover the viewfinder with the supplied cover, so as to not allow light to enter in via the viewfinder.

Is this really necessary? It it something I should be concerned about? Seems like a real pain.

Art Scott

Yes & yes...extraneous light can cause probs.

It was a problem with film SLR's also especially when doing very long exposures.............

Qarik

MileHighAko wrote: »

My Nikon cameras came with a little plastic viewfinder cover. The manual says that if you're taking photos without your eye up to the viewfinder, you should remove the rubber and cover the viewfinder with the supplied cover, so as to not allow light to enter in via the viewfinder.

Is this really necessary? It it something I should be concerned about? Seems like a real pain.

I suppose it could effect your exposure a touch. I wouldn't worry about it in general though.

CodyBoxer

MileHighAko wrote: »

My Nikon cameras came with a little plastic viewfinder cover. The manual says that if you're taking photos without your eye up to the viewfinder, you should remove the rubber and cover the viewfinder with the supplied cover, so as to not allow light to enter in via the viewfinder.

Is this really necessary? It it something I should be concerned about? Seems like a real pain.

And it's really easy to lose. Maybe a small dark cloth kept in one's camera bag and thrown over the camera as a hood?

yendikeno

Yep

Seymore wrote: »

Light coming in thru the viewfinder can affect your meter/exposure. Even using your hand to "shield" the viewfinder can correct this issue.

that's what I do as well when the camera is on a tripod and it's a long exposure.

Matthew Saville

Never used one of those little things in my life, always lost them within minutes, or never taken them out of the box.

If you find yourself in a situation where you need to block the viewfinder, (night exposures with a bright light behind the camera) ...a bit of tape will do just fine. I always keep a small amount of varios kinds of tape here and there in my bag; gaffers tape, electrical tape, and duct tape. :-)

=Matt=

Internaut

Never used.....
I haven't used one of these and have never had a need for one. I do put my hand over the VF though. The worst problems I've had with long exposures have been caused by forgetting to remove the UV filter.....

JimKarczewski

If you are shooting somewhere REALLY DARK (like oh, Moab, UT) I wouldn't even worry about it. Somewhere where there is a light source on the back side of your camera... tape it. One should always keep gaffers tape handy, hell, even if it's like me, I keep a 4-5" strip on my flash, just in case I need it.

Photoskipper

The film camera always came with the viewfinder cover in the good old days. It was useful for the long exposure and make sure no light going in to the viewfinder and prism which in tern affect the light meter and film.

Such small cover usually has loops to hang on the strip to avoid misplace. The old 300D DSLR came with it but not for the 5D and 5D Mark II. I cannot find it in their accessories these days.

Richard

My Canon 20D and 50D both came with a little rubber one attached to the strap. I used it once when taking a long exposure night shot, but I can't say that I ever noticed a difference.

Icebear

If you shoot manual it matters not at all.

cab.in.boston

Icebear wrote: »

If you shoot manual it matters not at all.

I don't think that's true. On long exposures, light entering through the VF can make its way to the sensor (the mirror is raised, but it's not opaque). You don't have to worry about it, b/c on your D700, there is a VF shutter that closes itself for you.

Matthew Saville

cab.in.boston wrote: »

I don't think that's true. On long exposures, light entering through the VF can make its way to the sensor (the mirror is raised, but it's not opaque). You don't have to worry about it, b/c on your D700, there is a VF shutter that closes itself for you.

Indeed. The exposure mode does not affect whether or not stray light can get to the sensor through the viewfinder.

As others have all agreed; you can safely toss / box the little do-dad, and just use a bit of tape if you ever need to make a night / long exposure when there is also a bright light source shining on the viewfinder. Problem solved!

=Matt=

Icebear

I do mostly architectural photography. I have shot, literally, thousands of images using cable releases, radio releases, and laptops, where the camera (D70, D200, D300, D700) was unattended on a tripod. The vast majority of these exposures were at low ISO and exposures between 1/25 and 2.5 seconds. The only time covering the viewfinder made any difference was on the rare occasion that I was in Av. I have NEVER had an issue with light entering through the viewfinder affecting the shot in manual mode. I expect the only effect it might (theoretically) have (in manual mode) is to reduce overall contrast. I have never felt the need to test it by purposefully shining a light through the viewfinder.

You can very quickly see the effect it has on your metered exposure (in metered modes) without even taking a shot by watching the settings change as you cover and uncover the viewfinder with your hand, but in manual mode, not in my real world experience. Sure, there are imaginable situations where you are shooting a dark scene with a bright light behind the camera in which it is (theoretically) possible for light entering the viewfinder to affect the image, but I suspect that in 99% of the real world shooting situations it's a non-issue.

I speak from experience. This is my normal MO in shooting.

Dan7312

I did some tests with my Canon 7D. My conclusion is that light going into the eyepiece can affect metering but has no affect at all when shooting in M mode.

The metering is pretty simple to see. I used Av with f7.1 in a dark room. that is an room with some semi-transparent curtains drawn so the room had a little filtered sunlight in it.

With hand over eyepiece the exposure was 5 seconds.

With a flash light shown into the exposure was 1/2 second.

So no suprise here, when metering light passing through the eyepiece enters the camera and affects the meter sensor.

To test to see if it had any effect on the image when you take a shot, I switched to M mode with f7.1 and 5 sec, the setting the camera had metered in Av mode. I also set the lens to manual focus and used live view to do the focusing.

I turned off live view and set mirror lockup on, and plugged in the shutter release cable.

I did one shot with my hand covering the eyepiece, below. This image and the following one were shot raw and I chose shade as the white balance for both when I made the jpg's in lightroom so I could compare any color changes in the shots.



Then I did another shot with the flashlight shining into the eyepiece. I was careful to wrap my hand around the flashlight so very little of it went into the room. I got this shot:




I don't think there is a diff in color. The historgrams are almost identical.

I did a test with brighter flashlight and confirmed that the light does enter the camera while it is metering. I could see the light from the flashlight projected through the lens onto the wall, even the little focus squares were projected onto the wall.

When I fired the shutter though, it cut of the light being projected onto the wall. So there is something that cuts off the light coming in from the eyepiece when the shutter fires.

I think these tests confirm what Icebear has found by experience. Light going into the eyepiece can affect metering, but has no affect on the actual shot. So if you are using Av or Tv covering the eyepiece may make a difference because if you don't the camera may get an incorrect meter reading. If you shot in M mode covering the eyepiece makes no difference at all.

Matthew Saville

Dan7312 wrote: »

I did some tests with my Canon 7D. My conclusion is that light going into the eyepiece can affect metering but has no affect at all when shooting in M mode.

The metering is pretty simple to see. I used Av with f7.1 in a dark room. that is an room with some semi-transparent curtains drawn so the room had a little filtered sunlight in it.

With hand over eyepiece the exposure was 5 seconds.

With a flash light shown into the exposure was 1/2 second.

So no suprise here, when metering light passing through the eyepiece enters the camera and affects the meter sensor.

To test to see if it had any effect on the image when you take a shot, I switched to M mode with f7.1 and 5 sec, the setting the camera had metered in Av mode. I also set the lens to manual focus and used live view to do the focusing.

I turned off live view and set mirror lockup on, and plugged in the shutter release cable.

I did one shot with my hand covering the eyepiece, below. This image and the following one were shot raw and I chose shade as the white balance for both when I made the jpg's in lightroom so I could compare any color changes in the shots.



Then I did another shot with the flashlight shining into the eyepiece. I was careful to wrap my hand around the flashlight so very little of it went into the room. I got this shot:




I don't think there is a diff in color. The historgrams are almost identical.

I did a test with brighter flashlight and confirmed that the light does enter the camera while it is metering. I could see the light from the flashlight projected through the lens onto the wall, even the little focus squares were projected onto the wall.

When I fired the shutter though, it cut of the light being projected onto the wall. So there is something that cuts off the light coming in from the eyepiece when the shutter fires.

I think these tests confirm what Icebear has found by experience. Light going into the eyepiece can affect metering, but has no affect on the actual shot. So if you are using Av or Tv covering the eyepiece may make a difference because if you don't the camera may get an incorrect meter reading. If you shot in M mode covering the eyepiece makes no difference at all.

That's good to know! So all we really need to do is make sure there isn't any light coming in through the viewfinder when we're metering...

Of course your light meter will still try to fool you no matter which exposure mode you're in, you just have the choice of listening to it or not, when in manual mode. Moral of the story - shield your viewfinder when metering, don't worry about it when clicking the shot.

=Matt=

Icebear

Matthew Saville

richy wrote: »

...
Has anybody actually stuffed up a shot because of light coming in via the VF?
...

Yes, in certain photojournalism situations where I find myself giving Aperture Priority a try, and then needing to shoot an overhead shot where I hold my camera way up and point it down, the sun DEFINITELY comes in through the viewfinder and throws off your metering, bigtime... If you ever have to shoot with your camera way from your eye, stick with Manual and set your exposure making sure that there isn't light coming in from anywhere else...

:-)

Emmett

Will this effect still be apparent when using live view or video on my 5D2 where the eyepiece is uncovered and the mirror is up?

cab.in.boston

Most of the time I am framing/metering with my eye to the VF, so I hadn't even considered the effect of light coming in backwards affecting the meter. That makes all kinds of sense if you're shooting tethered. Wouldn't it still affect the meter in M mode, though? Whether or not you listen to it is a different question. Certainly if you're shooting M using an external meter, it should be pretty much a non issue.

I'd always thought that covering the VF was important when taking very long exposures, as in 30s or longer, when even a small light source coming in from behind could make its way to the sensor and affect the image, even if the light wasn't sufficient to affect the meter.

Art Scott

richy wrote: »

Ahhh interesting The mirror stops any light spill onto the recording medium right? (be it film or digital)

Not totally light can still spill around the edges of the mirror.

billythek

Thanks for this thread. I had convinced myself that I needed that little doodad, due to some differences I saw while taking long exposures at night. I'll need to experiment some more.

cab.in.boston

Seymore wrote: »

Yes and no... It will affect the meter, but M mode is for shooting and the meter will not change any setting in M mode. All other settings can be affected by the meter and covering the VF can be important in those cases.

Yes, that's my point. It won't change any of the exposure settings, but if you're using the internal meter to make those settings, it will indirectly change the settings, since you'll make your settings incorrectly thanks to leaked light from the VF.

Also... once the mirror is up, light coming in thru the VF can't make it to the sensor.

Not true (at least not according to my copy of Thom Hogan's Complete Guide to the D300). The mirror is only partially silvered in some of its area so that some small amount of light passes through, hits a secondary mirror behind the primary, which reflects light downward to the meter. Due to this partial opacity, when the mirror is raised, it still allows a (admittedly very small) amount of light to pass through, which could make it to the sensor, even with the mirror raised.

Edit: Sorry... not the meter, the AF sensors are located on the bottom of the body and require the partial opacity and secondary mirror. Still, the main mirror is only partially silvered.

pilotdave

MileHighAko wrote: »

My Nikon cameras came with a little plastic viewfinder cover. The manual says that if you're taking photos without your eye up to the viewfinder, you should remove the rubber and cover the viewfinder with the supplied cover, so as to not allow light to enter in via the viewfinder.

Is this really necessary? It it something I should be concerned about? Seems like a real pain.

I shoot with my viewfinder uncovered a lot. It bites me every now and then, when direct sunlight is able to enter the viewfinder. Here's an example out of lightroom...



The highlighted shot is darker than all the others in the same burst because the sun was directly behind me for that split second. Camera was on Tv mode and went from f/5.6 to f/11 for that one shot. Don't know what the effect looks like in M mode.

Dave

run_kmc

I've seen it on long exposures (one minute or more) affect my final picture.

Dan7312

I enhanced my testing. My initial conclusion that in M mode you didn't have to worry about light going into the eyepiece is not correct. Even when you shoot in M mode, some light will leak in and hit the sensor.

My 7D again. lens cap left on, f22, 30" exposure, M mode, ISO 6400.

Test 1. Take image with hand over eyepiece. Result is dead black image. Histogram is one, looks like one pixel wide, vertical bar on the left.

Test 2. Shine flashlight into eyepiece. Result is a white image with a short vertical back line in the middle, and a little gray at the bottom. Histogram is is big mountain in the right.

I also did the test at ISO 200, and the result is the same, except not as pronounced. The flashlight test didn't produce a white image, just a not really black one. Also histogram had some smaller mountains.

So, yes, even in M mode light going into the eyepiece can hit the sensor and affect the result.

BTW the light leaking in would reduce contrast, but not evenly across the image.

Dan7312 wrote: »

I If you shot in M mode covering the eyepiece makes no difference at all.