Amateur Photographer & What Digital Camera: Module 2

Hello everyone, it has come to my attention (and the other Diploma tutors) that some students have had problems completing module 2. We've put our heads together and come up with some extra advice and clarifications that should hopefully demystify this module and make it easier to complete.

Barney

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This is the recommended sequence for shooting the images of the grey card:

1 Set your card up, Making sure that it is lit evenly, under continuous, single-source light (daylight on a cloudy day is ideal).

2 Select a low ISO sensitivity (AP’s grey card tests are made at ISO 400, and it is a good idea not to shoot at higher ISO settings because noise can influence the results of the test).

3 Set your camera up on a tripod, and fill the frame entirely with the grey card, so that there is no border, or background at all in the image. If necessary, set manual focus to avoid your camera ‘hunting’ for focus.

5 Select spot or partial metering on your camera (evaluative/matrix metering can give variable results) and set the shooting mode dial to manual exposure.

6 Set your shutter speed to 1/60sec then adjust your aperture (and if necessary the ISO setting) to achieve a ‘correct’ exposure at this speed. Take a picture.

7 Now, without changing aperture or ISO values, take a series of pictures, at these shutter speed settings:

1sec 1/60sec (your ‘correct’ exposure)
1/2sec 1/125sec
1/4sec 1/250sec
1/8sec 1/500sec
1/15sec 1/1000sec
1/30sec

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Clarifications/Additional Instructions

Please submit the images that you have shot in the grey card test, but make sure that they are resized, so that they will all fit onto the memory stick. We recommend resizing to a width of 800pixels.

Please name each one according to the shutter speed at which it was taken, ie “1/60sec.jpg”. If your computer does not allow you to save documents with the ‘/’ symbol, use ‘th’ instead, ie “60thsec.jpg”. This will allow your tutor to check whether you have completed the test properly.

In the self-assessment, where the module notes ask you to find “the two images at the extremes of the range, namely the lightest and darkest images that still maintain detail in the grey card”, the word ‘detail’ is a little misleading, since there is no detail in a grey card.

What you should do is find the lightest and darkest images that show some tonal information – ie the darkest image that isn’t quite black, and the lightest that isn’t quite white. You do this using the dropper tool in Photoshop. In AP’s dynamic range tests, we treat any image with average RGB values of less than 10 as effectively black, and any with RGB values of more than 245 as effectively white.

The notes state that “Your ‘correct’ exposure should measure around 128/128/128 in each channel”. This is not always true. Most modern DSLRs deliver a midtone of roughly 120-130, but some are darker, and some a little lighter. Don’t worry if your camera’s midtone does not quite average out at 128. If it is darker than 100, or lighter than 140 though, you should repeat the test.

In the questions in this section, questions 1 and 2 ask you to find how many stops you can over/underexpose whilst still recording “detail”. The word ‘detail’ in these questions should be replaced with ‘tonal information’, and means how many stops can you over/underexpose before an image gives RGB values of less than 10, (virtually black) or more than 245 (virtually white).

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Thanks everyone, feel free to PM me with any questions.

Edited by barney britton (06/08/2008 15:14)

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