Find a scene that has a wide range of brightness- appears contrasty, in other words. Find the exposure setting at which the highlight clipping warning just appears, make a note of the aperture and shutter speed. Next, increase the exposure for a second shot by one f-stop. This will show a wider area of highlight clipping. Then take three more shots in which you decrease the exposure each time by one f-stop. You should then have five frames, each separated by one f-stop.
Compare all these images side-by-side. What differences do you see? Specifically, make notes on the following aspects of the highlight appearance:-
– Complete lost areas of visual information
– A visible break in the form of an edge between nearly-white and total white
– A colour cast along a fringe bordering the clipped white highlight
– A colour saturation
It’s important to understand for this exercise why blown highlights occur, in what situation they occur, and how to prevent this from happening. I took a photo of a beautiful snowy forest scene for this exercise- with the white snow and bright sky contrasting with the dark trees.
Image 1- (f4.0, 1/100) Small highlight clipping. I found it quite tricky to figure out how to show the highlight clipping in photoshop as I didn’t take the photo in RAW. However, I found a way to do this by adding a threshold layer. The highlight clipping below is shown in yellow. It took me a couple of attempts to get a slight amount of highlight clipping in this scene. There is only a very slight amount of clipping in the white sky in this shot. I further analyzed this shot by zooming in on the clipped areas. Upon closer inspection it would appear that it is a couple of white clouds in the sky that have caused this highlight clipping. I looked at the check list above to see what the image had incurred. I don’t think that the problemed area is really prominent enough to cause any of the problems listed.
Image 2- (f4.0, 1/40). I had my camera set on manual exposure, so I could easily increase the exposure by one stop through increasing the shutter speed. The overexposure resulted in a lot of highlight clipping in this shot. The black and red in the image below show the parts of the photo that were blown highlights, and therefore exceeded the camera’s dynamic range. Upon closer inspection of this shot I can see that there is a complete loss of visual information in the sky and in the snow along the road, which both show a loss of detail- and now appear as large masses of bright white. There is also visible breaks present in the form of an edge between nearly-white and total white, specifically in the sky. I cannot see a colour cast or any colour saturation present.
Image 3- (f6.3, 1/40) I decreased the exposure by using a higher f-stop of f6.3. This reduced the highlight clipping dramatically from the previous shot. The right side of the sky still appears as a mass of white, and in the clipped areas there is a complete loss of any sort of detail.
Image 4- (f7.1, 1/40). I decreased the exposure further by again going up an f-stop to f7.1. This resulted in absolutely no highlight clipping in the image below. The check list does not apply to this image as there was no clipping. The detail in the sky has been restored slighting, and it is now appearing a light blue colour as opposed to bright white. The slightly reduced aperture has resulted in a more detailed image, and has indeed fixed the problem of highlight clipping. However, the image does not look underexposed.
Image 5- (f8.0, 1/40) I decreased the exposure once more to f8.0, and again this resulted in no highlight clipping in the image. The detail in this image has again been maximised by the lower aperture, which has also consequently removed the highlight clipping. Again the details of the sky are being restored, and it has become a much more pleasing shade of blue.