Exercise: Your camera's dynamic range.

Outline: Undertake a series of instructions to determine the dynamic range of your camera.


Using my Canon EOS 1000D,  I managed to take this image on a sunny afternoon (yes, sunny days can be very sparse in Wales).

ISO 100 F13 1/500 -1/3exp

There is a good scale range from bright white door frames to deep shadowed windows. My camera was at the lowest ISO setting of 100 and on an auto aperture/shutter speed setting to allow me to gather the measurements of the separate areas in the image. I used the wide angle lens to take the image and then zoomed into telephoto focal length using the center weighted average setting to pin point the measurement of each position.

These were the readings taken of the scene. There is a vast range of aperture and shutter speed values shown indicating the differences in the levels of brightness.

Using photoshop elements 9, I then zoomed in to 100%, as requested in the exercise, and focused on the white area above the door.

Here we can see, in the pixel value sampler, that in the white area, the values are 215 in each of the three colour channels.

I chose the shadowed area in the glass door to highlight the shadow values. It has detailing through the 'reflection' but there are also some areas of noise.

Here, the values shown are a lot lower, down to 6 and even 4 in the B channel.

Given the normal lens aperture range, my camera's dynamic range has a healthy 9 stops. The brightest white area is measured at F14 (1/500) and the darkest shadowed area is measuring F6.3 (1/100) so in aperture AND in shutter speed values we have 9 stops difference:

Aperture: F6.3, F7.1, F8.0, F9.0, F10, F11, F13, F14
Shutter Speed: 1/100, 1/125, 1/160, 1/200, 1/250, 1/320, 1/400, 1/500

Conclusion: I think this was a great and simple exercise to explore the subject of dynamic range and also, for me, about learning more about the qualities of my camera. This course is proving to be a great insight into the basic areas of using the camera properly and also of the systematic way of taking images and editing them. As a beginner to digital photography, I find simple yet effective exercises like this one a really good way to learn.

Exercise: Your tolerance for noise.

Outline: Using a scene with the following criteria:

• Daylight indoors
• A combination of sharp detail and textureless area

set up a tripod and take a series of identical photographs, changing the ISO setting from one to the next.

Being completely honest, I haven't had fun completing this exercise. I've taken numerous different shots as I expected the outcome to be a lot different than it has on all attempts.
This is the set of images that I took in ISO setting sequence:

My camera has 5 ISO settings: 100, 200, 400, 800 & 1600 (seen here in order). I took photos of a toy box against a textureless wall where some shadow could be seen and have cropped the image to highlight just the shadowed areas.
With aperture priority at F22 the shutter speed fluctuated from 6 secs at ISO 100 to 0.40 secs at ISO 1600.

Looking at the images altogether, there doesn't seem to be much difference between them. And this was the outcome with the other 4 attempts of taking these images.

If there are any comparisons to be made here, I will state that the higher the ISO settings, the more grain you can be seen in the images although the actual shadow area seems a little lighter making the contrast slightly less.

Conclusion: I have had previous experience with noise appearing in images where I have needed to use a high ISO setting, it's just i haven't really shown a great example through the images for this exercise.  Looking at this image I took during a festival in the summer and used for my final assignment in The Art of Photography;

The image was taken in a stage tent during the day and so I needed a high ISO setting. The grain in the image is very noticeable through the artists skin, hair and even the background area. This is a prime example of noise that is not real detail and is purely due to the high ISO setting.