Depth of Field

[lamasu]

Hello all,

I have been experimenting with F/stops and the depth of field concept, but for some reason, I cannot achieve the desired results. I have a Powershot SX10 IS and when I shoot during my son's baseball game, I turn the setting dial to AV and set it at f/2.8. But as soon as I zoom in onto the pitcher's mound, my f/stops change to a higher number and renders a photo with a wide depth of field. I am looking to snap a photo of my son pitching and blur the background while he is in clear focus. Any help would be greatly appreciated. If my explanation sounds amateurish...I am a newbie...but love photography :)

[dmwierz]

Your lens is a "35mm film equivalent: 28-560mm f/2.8-5.7", and what this means is, it's approximately an f/2.8 at its widest setting (28mm equivalent) and f/5.7 at full zoom (560mm equivalent).

Only the most expensive glass is fixed aperture (zooms or primes) meaning they will maintain their aperture throughout the zoom range. You've discovered one of the limitations to using a point and shoot to cover sports.

[justincase724]

A lot of times, zoom lenses have a mixed minimum aperture. At it's widest, it may be able to get f2.8, but zoomed out, it may only be able to go as low as f5.6. It should say so on the front of the lens.

Edit: dmwierz beat me to it.

[DDCSD]

To add, with a P&S you're going to get a lot of DOF anyways. The smaller sensor makes for a much wider DOF. You're not going to be able to get those nice blurred backgrounds with a P&S.

[DDCSD]

And welcome to POTN!!!

[lamasu]

Thank you all for your input. I really appreciate you taking the time to respond.

[NVcameraman]

He is a site that will give you some good information to depth of field.

http://www.bobatkins.com/photography/technical/dofcalc.html