Part 4 - Exercise 2

Higher and lower sensitivity

For this exercise the ISO was increased in order to increase the sensitivity to light of the camera and thereby mean that higher shutter speeds and/or higher apertures can be used but still the same exposure is achieved.

The price that must be paid for this increased sensitivity is (in digital photography), increased noise.

The first shot above is f3.6, 1.5 sec, ISO 200. The low ISO is forcing a large aperture and low shutter speed - so depth of field is low and there is also camera shake. The 100% magnification shows the blur from the camera shake and also that the candles are heavily out of focus.

Going up to ISO 800 still only gets me f5.0 and 1/9 sec . One of the reasons I chose my camera is the particularly good image quality at high ISO. So actually there is little noticeable noise at ISO 800.

ISO 2000 gets me f5.0 and 1/20 sec. Still not much noise. The bird has good detail, but there is very little depth of field here - so the candles in front of the bird are out of focus.

ISO 3200 gets me f8.0 and 1/15 sec. This is probably the best compromise point for me - there is reasonable depth of field and the shutter speed is just fast enough to minimise camera shake (with the lens' optical stabiliser also assisting). At 100% zoom there is some visible noise in the flat coloured areas, but this is a price worth paying for the increased depth of field and shutter speed.

ISO 6400 gets me f10 and 1/20 sec. The noise is starting to show here and actually making the image slightly blurry when viewed at 100% - this is probably the noise reduction kicking in as the camera generates the jpeg.