PDA

View Full Version : So, a quick DoF checkup...



Paradox
07-25-2007, 01:52 PM
Evening all.

I'd just like to ask some of you to have a quick flick over what I'm doing in the way of Depth of Field here to see what I can do to improve it.

At macro distances it seems to be going well - The FZ50 seems to be able to focus onto something that's practically inside the lens (As long as you focus manually, although the AF seemed to work well on the one time I got lazy enough to try it out). Aperture at 2.8, full wide angle, tight focus on the subject (Easy with the zoomed focusing window), and the background becomes a blurry mess. All is good and well with the world.

But I could use some advice on DoF at telephoto zoom ranges - I just can't seem to crack it. I can get everything in focus for a landscape easily, but trying to capture an animal or bird say at telephoto, everything remains sharp - is there anything that can be done to affect the DoF at telephoto ranges?

Thanks in advance for any advice you can give. :)

Chris

BLWNHR
07-25-2007, 02:40 PM
Simple answer is DSLR with f/4 or smaller lens.

Hope you brought your cheque book. :p

Your Pana digicam, when you zoom in, changes the aperture to something like f/6 or higher, taking away all the DOF.

Remember smaller aperture number, smaller amount of the photo in focus.

Vich
07-25-2007, 03:03 PM
Simple answer is DSLR with f/4 or smaller lens.

Hope you brought your cheque book. :p

Your Pana digicam, when you zoom in, changes the aperture to something like f/6 or higher, taking away all the DOF.

Remember smaller aperture number, smaller amount of the photo in focus.

As I understand it; DOF is a function of a few things:

1. Aperture. The larger hole (smaller number) has less DOF. So; f2.8 has less DOF than f8.

2. Distance to subject. Given everything else identical (aperture, focal length, etc) you will have far less DOF at 10 inches than at 50 feet.

3. Focal Length. A 300mm has far less DOF than 28mm.

4. Since a tiny P&S sensor doesn't actually have 300mm, it only has 300mm EFL (Equiv Focal Length), but it might actually be say, 17mm, the DOF is far greater (ie: you have less control). So; Sensor Size is a major factor. Ergo; BLWNHR's answer of "DSLR", because it has a bigger sensor.


I'm no expert, but somewhere in the links on my sig is a detailed explanation.

The short answer is; if you are using your longest tele and widest aperture but DOF is still flat, then you can't do in on your camera unless you can move closer.

Also note: On a DSLR, one would never think of taking true macro shots at f2.8 since the DOF could well be only slightly more than a paper - so everything might be OOF. f8 will give very nice blur to all but the exact 1/2 inch or so that's wanted.

AlexMonro
07-25-2007, 03:43 PM
There's a good tutorial on Depth of Field here (http://www.cambridgeincolour.com/tutorials/depth-of-field.htm).

Paradox
07-26-2007, 02:11 AM
Thanks all - I'll stick to getting a bit closer then until I manage to acquire the money required to buy a good DSLR. :)

Pave
07-29-2007, 01:06 PM
Your Pana digicam, when you zoom in, changes the aperture to something like f/6 or higher, taking away all the DOF.


I don't know about FZ50 but my as far as my FZ30 is concerned, when I zoom in to the max (420mm), the aperture could be f/3,7 :D

Paradox
07-29-2007, 01:17 PM
Thanks Pave for pointing that out - confirmed as the case for the FZ50 as well. At 420mm the maximum apature is f/3.7...