This exercise was about finding the dynamic range of my camera (Nikon D5500)
A cameras dynamic range is the difference between the lightest light and darkest dark which can be seen in a photo. Once the subject exceeds the camera’s dynamic range, the highlights wash out to white, or the darks become black blobs (noise).
I had to find a high dynamic range scene with the following conditions:
- bright sunlight
- at least one brightly reflecting surface
- an area of deep shadow with a dark surface
I must admit i’ve been fairly stumped by this exercise. I noticed that many student blogs were missing this exercise. Having researched online extensively and having studied other student blogs and discussed in forums I think i’m somewhat clearer. Some articles adjust aperture while others adjust shutter speed. I’ve decided to crack on with it and not waste any more time deliberating over it.
In a nutshell – using a fixed ISO and aperture I am going to measure the difference in shutter speeds of different areas of brightness in one image. Spot metering will help me identify the correct shutter speed. The range between these results will be my camera’s dynamic range.
Firstly I had to set the exposure and make sure the it was just at the point where there were no longer any highlight clipping warnings on the reflecting surface (white wall). The exposure settings where the highlight clipping had just disappeared was 1/200, f.22 and ISO 400.
Next I had to measure and make note of the brightness of the white wall and two or three of the darkest shadows. I used the spot metering setting as this enables me to measure specific areas. I measured the white wall at 1/640, f.22, ISO 400. I then measured 2 dark shadow areas (the bricked pavement area and the dark shadow by the palm and wall) as 1/60, f.22, ISO 400 and 1/30, f.22, ISO 400 retrospectively.
Part 2 required me to open the image to 100% in my software and check that the white area’s pixel values showed just under 255 on all three channels. They measure at 249 on all 3.
I was the required to zoom into the shaded area, brightening it with my software and comparing the areas of real detail against noise.
As you can see from the above image it is now extremely difficult to tell the difference between detail and noise. The darkest areas are extremely hard to determine.
SO now i’ve got my shutter seed variations I need to calculate the dynamic range. The OCA handbook states that most SLR’s have a range of roughly 9-10 Evs.
The Nikon i’m using has a total range of 1/4000 to 30secs, but i’m just going to look at the values i’m working with:
I seem to have produced a dynamic range of 13 Ev’s – this seems a little excessive considering the average is 9-10. However, after researching the average dynamic range of my model I came across this website http://www.dxomark.com/Reviews/Nikon-D5500-sensor-review-Low-noise-and-class-leading-dynamic-range/Measurements-Nikon-D5500-Excellent-dynamic-range that mentions the Nikon D5500 having a range of 14 EV’s.
Therefore i’m happy with my results, and have learnt how important this feature is when assessing shots. It’s essential while maintaining a technically satisfactory image, but is also a great creative tool for producing silhouettes, and generally making photos more art like and aesthetic.