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3 - Capturing the Image - Basic Digital Techniques

Basics - If you have spent several hundred dollars or more on your digital camera gear, then you really ought to spend a little time on getting the best from it. There are many in depth guides available on the web and in print if you want more detailed information. What I offer here are a few simple ideas that everyone should learn about and that will make a noticeable difference.

Exposure - Flashies and Histograms
over exposure flashies warn you that you are missing detail in the highlights

this histogram pushed up to the edge shows that exposure is incorrect

the white histogram is overall exposure, the other three show exposure of the primary colours
Correct exposure in a camera is about capturing the image with a good range of tones with some pure black and some pure white in the frame and plenty of detail in-between.

If you don't expose a picture correctly, then you will be missing details that no amount of adjustment in the "digital darkroom" will ever be able to recover, the detail just wasn't there in the first place.

Most cameras offer a couple of aids to getting the correct exposure at the time you take it, so allowing you to re-take if necessary and make sure you capture the image properly, these are the "flashies" and histograms.

At first sight the flashies and histograms on your camera may seem to be unnecessarily complex displays of information. They are your best guide to the technical quality of the picture you have just taken - learn to use them and become a better photographer.

Flashies

Your camera should be set up so that you can see the shot as soon as you have taken it. You may occasionally see flashing red (or other coloured) regions as in this picture (caught in mid-flash) sometimes the regions are flashing red then white, sometimes red then black.

Your camera is telling you that these regions are either over or under exposed and that you have lost some detail. lets say that there are 50 levels of brightness in the picture for simplicity. In the case of the picture to the left it is saying that some of the levels say 40 to 50 that should be distinct and have some detail are all being put into the level 50 category - the brightest, and all of the flashing pixels will be plain white in the file.

EV Compensation buttonWhat you should do about it in this case is to retake the picture while adjusting the exposure downwards i.e. allow less light through the lens so the bright end of the exposure scale is not overwhelmed. Use the EV Compensation button to do this.

Histograms

You should also be able to enable a histogram to appear immediately after exposure along with the reviewed picture. This tells you how well spread and so accurately captured the details of the picture are.

In the example to the left the histogram is pushed over towards the right hand side showing that there is some detail that is off the scale at that point and so will be missing from the picture. If the picture is underexposed then the histogram is pushed towards the left hand side. Again the answer is retake the picture with exposure adjustment.
Correct exposure File:Farm-Fresh tick.png Over-exposed File:Farm-Fresh cancel.png Under-exposed File:Farm-Fresh cancel.png
The peaks on this histogram are well spaced across it's width and not pushed against either edge. In this over-exposed image, the histogram is pushed up to the right hand side showing that highlight detail is lost. In this under-exposed image, the histogram is pushed to the left hand side showing that shadow detail is lost.
Basic Digital Darkroom Techniques
  The Original Image:

It has promise but it's a bit bland and there's no real focus on any particular element.

I'll be using Photoshop CS5 to make adjustments to this, though the changes I'll make are quite basic and other photograph manipulating software packages can also perform the steps I will take.

Before you start, make sure you keep the original image and save any changes to a different file or as a different filename or you won't be able to go back again if it all goes horribly wrong - believe me, at times it will!
  Step 1 - Rotation:

The original had a slightly sloping horizon, while I try to avoid this when taking pictures, it's difficult to get it right every time and often pictures are slightly off.

I rotated the image by 1 degree counter clockwise, you can see how the edges of the picture have tilted as a result of this.

Pick an element of the picture that should be horizontal or vertical to get this right. You can turn on gridlines if necessary while you do this to make it easier, turn them off again afterwards.
  Step 2 - Crop after rotation:

Cut off those long thin white triangles that result from rotating using the cop tool. Crop as tightly as possible so as to keep as much of the image as possible for the next steps.
  Step 3 - Crop to choose the most interesting part of the image and most pleasing arrangement:

Those mountains to the left were an interesting shape but all in shadow. The ice at the bottom of the picture is out of focus as it's too close to the camera.

In this case I chose to crop quite a lot of the original picture away so giving some foreground interest and a pleasing arrangement of mountains in light and shadow in the background.
 Finished manipulated image
Finished manipulated image

Original image
Original image
Step 4 - Contrast, Color balance and Sharpen:

The original image was too flat and lacked something. The final steps were to adjust the color balance very slightly and increase brightness and contrast - again very slightly. I used the automatic levels to do this and was reasonably happy with the results, Photoshop allows you to fade any effect applied so I toned down the automatic levels to what I thought was more suitable.

The last step was to increase sharpness.

The original is below the final image to the left, well worth taking the extra time and effort in the Digital Darkroom to improve the image.

The key is not to make too many changes and not to make them too drastic or you end up with something that just doesn't look real.

Also, make sure you save your original image for when thing go wrong.
 You decide what to show people

The possible downside of all these pictures that can be taken using digital cameras is that it's very easy and tempting to take a huge number of pictures of any particular scene, many of which will be very similar. There is nothing wrong in this in itself - it's one of the advantages of digital photography over film photography after all.

However, please make sure you edit out the also-rans and pictures that are so similar as to be no difference between them.

I have been subjected to other people's pictures myself where they maybe have two good shots of a scene, but have shown about ten that are very similar as they can't make the decision themselves as to which is the best one to show. It doesn't make the viewing experience better, it just tends to make it rather tedious.

So be a ruthless editor when putting together a slide show of your trip to the wilderness, it'll make what you produce all the more impressive for it.

Photographic pages - 1 - Equipment | 2 - Photography Technique| 3 - Digital Technique

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National Geographic Photography Field Guide: Secrets to Making Great Pictures
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The Basic Book of Photography, Fifth Edition
The Basic Book of Photography
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The Ansel Adams Guide: Book 1: Basic Techniques of Photography
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Ansel Adams prints and posters

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