Roses - playing with focal length / aperture

Our camera club assignment for this month is to try and build a better understanding of focal length, and using aperture to get the results we want in our photos. A better understanding of this would have helped my portrait photos last week!

Using my 28-80mm lens, I went out to take some pictures of a beautiful rose I spotted on the bush out in the dog run.

Wide shot in 'auto' mode - camera chose F9, lens at 28mm

 Zoomed in to 60mm, exposure: 1/4000, hand set f-stop at F4.8 - low as it would go. Just the central part of the flower is in focus, and the rear pedal is soft and has no detail

Still 60mm, exp: 1/800, changed f-stop to f8, regained some detail on the rear pedal, and the leaves in the background are more in focus

Still 60mm, exp: 1/400, upped f-stop to f25, more detail on rear pedals, and leaves behind are in focus. Because the f-stop is a larger number, the aperture (the opening in the lens) is smaller, so the picture is a little darker - less light was let in, even though the camera compensated by upping the exposure. But it can be brightened up in editing.

Brightened up using Picasa. If I had a tripod, I could set for a longer exposure at this same f-stop and brighten it without editing tools.

 Slightly different angle, zoomed in to 70mm, exp: 1/500, f18 to get detail on the rear pedals, brightened up in Picasa

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