My Nature Reserve and Dealing with Underexposed Images

April 22, 2016  •  Leave a Comment

For a couple of nights this week my wife and I have been sitting down in our nature reserve on the edge of Dartmoor in Devon, England just watching, listening and getting bitten by bugs especially by the river Tavy. I can now call it our nature reserve because it is alive with wildlife. Recently we have seen Roe deer, Rabbits, Foxes, Badgers, numerous birds, Newts, Voles and on one of the nights we were watching Bats. I do not know what type they were but Greater Horseshoe Bats, Lesser Horseshoe Bats and Long-Eared Bats have all been recorded in the area surrounding our nature reserve. We also believe we have Otters and Dormice, Fantastic.
 

At home we have had 3 Jays appear in the garden and as the 5 that appeared for a few weeks last year they are after the fat balls rather than the peanuts! I will try and get some images this weekend weather permitting.
 

 

Dealing with Underexposed Images
 

 

I was away from home last week because of work, with a lot of time to spare, which I didn't think I would have, so I started trawling through a lot of the wildlife photos on Facebook. Some were outstanding, some were good and a few left me thinking what were you trying to photograph. I also noticed that there were also quite a few wildlife photos that were underexposed which was a shame because everything else about these wildlife photos were really good, good composition, good focus, great subject but so underexposed that it spoilt the photo. What do I mean by underexposed? Well when you look at the photo the subject is very dark, the surroundings are dark grey and the sky is one dark grey mass (usual skies for England, but some photos were taken abroad). When I say the subject is very dark I do not mean it was a silhouette but it was hard to see any great detail or bright colours. This is all down to not enough light getting through the lens to the sensor to expose the subject correctly. There are several reasons for this, not fully knowing how to use a camera or understanding how a camera works and rushing to take the photo with a bright background being a couple of them. There are several ways to overcome this problem. You could deal with it during post production unless you underexposed the image too much and have lost the image information. Will Nicholls, who runs a really good website Naturettl (www.naturettl.com ), has written an article about rescuing overexposed and underexposed images. The biggest thing to be aware of is that brightening an underexposed image WILL introduce noise especially in the dark areas of the image therefore you are better off doing something about underexposed images, in camera, when taking the shot.
 

When I say the person does not fully know how to use a camera or understanding how a camera works I am being a bit harsh but truthful. The main reason underexposure happens is because a camera's exposure meter sees everything as shades of grey. If you don't believe me then take a photo of just a white wall, completely fill the screen with the wall and another photo of just a black wall. When you look at the images they will both be roughly the same colour grey, 18% grey in fact. I remember years ago I had an “18% grey” card and used to use this to adjust my exposure by taking a reading off it in the same light as the image I wanted to take. After a while I started using other everyday objects, rather than the card to give me the exposure settings, like grass, a boulder, trees etc. Our eyes can see about 10 stops of contrast, between pure white and pure black, but a camera can only see about 5 or 6 stops. This is why when we view a scene and then take a photo of it; it does not always turn out exactly the same. Once you understand how an exposure meter works then you can start adjusting your exposure to suit the scene. Knowing how to set your exposure really helps you move off full and semi program modes, aperture priority and shutter priority, and onto full manual mode where you can be most creative with your photography. The time to really concentrate is when the background is brighter then the subject you are after. Think about taking a photo of a bird in a leafless tree and you are pointing the camera upwards at the sky or there is a large amount of sky showing in your image. It happens more with a grey cloudy sky then with a bright blue sky. The large amount of sky, brightness, fools the camera into thinking the scene is brighter than it really is. When taking a photo try and get into the habit of looking at the histogram after you have taken the shot. On Canon cameras the histogram is divided by feint vertical lines and each line is roughly a stop apart. For other makes check your histogram because this is a great guide to show you how much compensation you need to adjust. This is one of the biggest aids that digital cameras come with as it will tell you if you have overexposed your image, it is built up on the right, or underexposed your image, it is built up on the left. If you are underexposing your image then remember to add exposure compensation. The amount you add depends on how underexposed your image is and it could be anything from a third of a stop to two stops or even more but this is rare. Recently I have taken an image of a singing Yellowhammer sat high up on a branch in a tree and I had to add two and a third stops to stop it being underexposed. For most Canon dslrs you can add exposure compensation by rotating the control dial on the back of the camera either clockwise or anti-clockwise. If the control dial is not set up like this then you can change it within the camera settings. It makes sense to have this kind of setup because you can change the exposure compensation, whilst still looking through your viewfinder, with your thumb. Either within the viewfinder or on the LCD panel on the top of the camera you will see the exposure level indicator. This looks like a small shield with +1, 2, 3 on one side of it and -1, 2, 3 on the other side of it. Your particular Canon camera might only go to +2 and -2. For other makes of camera please look up exposure compensation in you manuals as there are several ways of doing it for each make of camera. To add exposure compensation move the adjustment level to the + side. Remember that doing this will reduce your shutter speed if you are in Aperture Priority mode or your aperture if you are in Shutter Priority mode. You want the lines on the histogram to be close to but not over the right hand margin. This is called Exposing to the right (ETTR). Doing this gives you the most information and tones within your image, which is what you want before you start post processing your image. There is more information in the lighter tones than in the darker tones, which contain noise, and this is why photographers expose to the right. Get used to the types of images you need to add exposure compensation and banish underexposed images for good.
 

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