Well? Do you? Chances are that like me you probably don’t, at least not until something goes wrong. I do read a lot of “how-to” articles however in both print and digital media and something I see regularly, and no doubt it’s in the manual too, is that you should cover the eyepiece of the camera when shooting long exposures. Not that I usually bother but every now and then I do get all conscientious and do as recommended. Until last week though I’d never experienced any problems with this somewhat cavalier approach.
Trying some long exposures on a very slow moving river in Scotland last week I set the camera on a tripod with a very bright sun above and behind me filtering through the trees. With a polariser fitted to cut glare on the water and a ten-stop neutral density filter for good measure I dialled in a five minute exposure, fired the shutter and wandered away to explore some bracket fungus growing a few yards away. When I checked the image back on the LCD screen to make sure I’d estimated the exposure time correctly I was surprised to see a magenta cast. A few minutes head scratching followed after which I decided to repeat the exposure but this time closing down the eyepiece blind on my Nikon.
Wow! As the two RAW files above show the oft-repeated advice to cover the eyepiece lest stray light upset the exposure is after all more than scare mongering. Given the right circumstances it does make a difference showing that it does make sense to follow the advice provided in the camera manual or by other users even when it seems that it is a bit over the top. To keep things in perspective though this is the first time it has happened to me since taking up digital photography and whilst it isn’t an issue when handholding as your head blocks the viewfinder I do take a large proportion of my images from a tripod and unless it is a short exposure when I do stand behind the camera I am prone to wandering around or even sitting down when using long exposure times.