Covering viewfinder on DSLR whilst Imaging

[gfletcher]

Hi Guys

I read recently that covering the viewfinder on your DSLR whilst imaging stops any stray light entering the camera.

Do most imagers do this?

Would it make any significant difference ?

I must admit it is something i have never thought of before.

What are your views?

Graham

[FraserClarke]

I've certainly noticed the difference even when just taking 30s nighttime exposures. I guess it depends what you have behind your camera when you image -- it if is in a dark field/observatory; might not be a problem.

Most DSLRs come with a little plastic cap that slots in over the view finder (may have to take the rubber eye shield off, depending on the camera).

[Psychobilly]

Yes I always cover over the viewfinders on my DSLR's whilst imaging ...

[Brinders]

Hmm, surely when making a manual exposure and then exposing, with the mirror flipped up and the shutter open, there shouldn't be any stray light finding its way to the imaging sensor? I would have thought it only necessary to cover the viewfinder if you were metering on auto - any stray light then would give an incorrect exposure. But I stand to be corrected!

Brinders

[brianb]

with the mirror flipped up and the shutter open, there shouldn't be any stray light finding its way to the imaging sensor? I would have thought it only necessary to cover the viewfinder if you were metering on auto - any stray light then would give an incorrect exposure.

That's my understanding too. If you have a propensity for shining searchlights at the back of the camera whilst you're imaging, covering the vf may make a difference ... in practice, in my experience, the only difference that covering the vf makes is that (a) you can't see through the vf when you forget to remove the cover, ( the cover gets lost when you do remove it.

[Psychobilly]

But are the mirrors fully silvered these days...?

I use a piece of black Duct Tape...

[FraserClarke]

Hmm, surely when making a manual exposure and then exposing, with the mirror flipped up and the shutter open, there shouldn't be any stray light finding its way to the imaging sensor?

Yes, but there is no need for the flip mirror to make a light tight seal when it is flipped up, so I suspect that most don't bother. Light still gets in round the edges (or through <100% reflective mirror as billy says)

I guess the real answer is ; try, and see if it makes a difference for you

[Psychobilly]

My take is if those photons I am trying to capture have been good enough to take the millions of years to travel across vast distances of interstellar space to head for my sensor then using a piece of tape that takes seonds (you dont have to remove the existing rubber cup) is the least I can do to give them "quite end"...

[Darth Takahashi]

Professional cameras such as my 1D MIII have a blind built in to the view finder that can be closed in situations where your eye isn't present at the view finder. This tends to be in studio type situations where the camera is used in a fixed setup for still model photography.

The reason is because light entering via the view finder can affect the metering of the exposure. It cannot effect the actual exposure itself.

Think about the light path! Light travels in straight lines and is reflected by polished high reflectance surfaces. There are small sections of semi silvered surfaces which are used by the cameras electronics but its highly improbable that stray light could enter here!!!

Neil.

[martin_h]

My film camera - canon A1 has a built in blind to be used when your eye is away from the viewfinder

[Darth Takahashi]

My film camera - canon A1 has a built in blind to be used when your eye is away from the viewfinder

I'm not surprised since the A1 along with the F1 were the professional cameras of their day. I had an AE1 Program, that was my first every SLR camera.

Neil.

[martin_h]

It still is my camera of the day LOL

[George]

I use a piece of black Duct Tape...

Yes I use this hi-tec method too

[zhgutas]

My take is if those photons I am trying to capture have been good enough to take the millions of years to travel across vast distances of interstellar space to head for my sensor then using a piece of tape that takes seonds (you dont have to remove the existing rubber cup) is the least I can do to give them "quite end"...

Now that's poetically put! cracked me up

Marius

[Dangerous-Dave]

A lot of Canons come with a little rubber cover attached to the strap for this very purpose. I rarely use it though, as I have not noticed much difference.

[jgs001]

I've never used the cover during imaging, but I don't have a light source that can impinge on the viewfinder directly. If that's a possibility then cover the viewfinder. It will affect the exposure and you'll get what appears to be misting in the image.