Aperture Priority & Depth of Field

Most folk on here will know all about it but I thought these two pictures were worth posting as an example (for anybody who doesn't know) how depth of field alters depending on the aperture setting you use.

F stop 36. Here the aperture is small so more of the background behind the flowers remains slightly in focus.



F stop 4.2. Here the aperture is bigger so the background behind the flowers gets blurred.



Both these pictures were taken using the 'aperture priority' setting where you select the aperture setting you want and the camera then selects a sutter speed to expose the shot.

For the F36 pic the camera chose 1/13 sec shutter speed - it needed the shutter open for more time as the aperture was smaller.

For the F4.2 pic the camera chose a faster 1/640 sec shutter speed - it needed the shutter open for less time as the aperture was wider.

Also note how the flowers in the foreground have also become softer - due to the narrowness of the depth of field in this instance.... Some good examples there.

Nice one Phil!

Yes - Should have added that foregrounds get blurred as well as backgrounds.

Some good examples there Phil

What setting on the dial on your camera did you use when taking that picture

Did you know that the zone of focus extends for 1/3rd in front and 2/3rds behind the focus point.

What this means is that in the example above if you could have turned to manual focus after focusing with AF, and moved the focus point slightly nearer the camera manually you would have been able to keep the flowers in the foreground in focus and those further back also.

If that does not make sense, blame it on the cider I've been drinking

Steve

Kcjack - both were taken on aperture priority setting (see text above) so the camera chose the shutter speed to suit.

Is that what you mean ?

What would that be on the dial, going to play tomorrow, I think I need to phone college for a photography course. I love photos but not techy minded.

Very true.

I understand what you're saying - a deeper focus area (2/3) behind the object than the shallower (1/3) in front. By knocking off the auto focus and focussing on the 'front' flower you can have a slightly deeper ranger in focus whilst still having the advantage of a wider (faster) aperture setting. Certainly a good tip when speed is an issue.

This was really just a quick demo for anybody that wasn't sure how the aperture size affected depth of focus.

As it was a 'simple' example I also didn't touch on how the distance from camera to subject also affects the results.

Perhaps that's for another time

Cider ? I'm Jealous - An early drive for me in the morning. Perhaps tomorrow night.