Exercise 29: Higher and Lower Sensitivity

This exercise requires me to take few pairs of photographs, in which each pair is take with a lower and higher ISO setting.

The exercise of comparing ISO noise was done (incidentally) in one of the earlier post here:

http://art-of-photography-sip.blogspot.co.uk/2012/03/at-iso-6400.html

The result is obvious. You can shoot at dark environment with higher ISO, but then the picture comes out to be noisy. One might draw the conclusion saying that we should not shoot at above certain ISO (say 1600). I used the thought that way as well. However, there is noise cleaning program to reduce (but not get rid of) high ISO noise, but no program to reduce handshake, wrong aperture, motion blur. I think the correct answer should be you keep the ISO as low as possible, but shutter and aperture should be more important.

Anyway, since I have done some comparison on ISO noise before, I shot something different this time. I try to photograph a flower with flash. Then turn off the flash and use high ISO and slow shutter.

This is with flash at 90 degree from the right of the subject, at ISO 100, f/18, 1/200s

If we turn off the flash, then 1/50s, f/18 will require a ISO 6400. Before talking about noise, notice that with weaker directional light (there is still modelling light from the flash, plus spill from a window on the right), there is less outline of the flower in the middle. This sample without flash gives a very soft impression.

Same thing with flash, but I move the flash now facing directly at the flower. Notice that the shadow disappear, and the flower looks rather flat.

Main light source is the modelling light from the same direction and some of the spill from nearby window (on the right). Now the flower looks very flat. This is at 1/25s, ISO 3200

Keeping the light in the front, this is with flash.

This is without flash, modelling light off, but at ISO1600, 1/13s. At this composition, lighting from the right looks much better than direct lighting.