Deep Depth of Field
 

What fstop are you guys using to achieve a deep depth of field, say for landscape shots? I try not to go above 7 if I can help it as I've noticed a loss in sharpness when using the Canon WA adapter. Usually I'm aiming for 5.6.

Kevin

having you aperture open as much as possible is ideal for shallow depth of field, so closing down the aperture will create deep depth of field, and as you said being the as wide as possible helps as well. But true there is some loss.

There will be resolution loss if the aperture is closed too much due to diffraction. At wide focal lengths and WA adapter I do not really see any reason to close more than 5.6 or so, even then the DOF exteds from maybe from a few feet to infinity.

Diffraction is something nobody can do anything about, so if you need more DOF you just use smaller apertures and suffer the consequences what comes to general sharpness and resolution.

That's right - camcorders that use such tiny 1"/3 chips shouldn't be used at stops smaller than about f/4.5 if the best sharpness is required. Remember too that diffraction is focal length dependent as well - the shorter the focal length the greater the diffraction losses.

So if you want great dof, by all means use very short focal lengths but don't be tempted to use small apertures - unless of course you're delivering in SD, in which case the limits blur (literally).

tom.

Man, you guys are preaching to the choir!

Here's a piece of a blog post I did that discusses this very problem:

I've been doing some reading and have read about a technique known as Deep Focus. They way I understood it was basically, if you have a wide-angle lens (as I do, the WD-H72) and keep the aperture as closed as possible (which I did, it was very, very sunny out) that you would have very deep focus, meaning that objects close to the camera would be in focus and objects further away would also be in focus. I was trying to add depth to the images so we see a great cruiser close to the camera but we can also see some other lovely auto in the background.

Well, this "Deep Focus" technique that I was trying is apparently a bit more advanced than me because a lot of my shots have soft focus. Not entirely out of focus, but soft nonetheless. And in all actuality anyone outside of "the industry" probably wouldn't notice. But I notice and it is annoying. Let's chalk this up to being "over educated." If I hadn't read about Deep Focus I never would have tried it and my stuff would be in focus. But you live and you learn.

Here's a link to the original post, and there are two more posts on the subject, following me trying to figure out how to color correct and "fix" my poor footage. I ended up doing ok.
Will Mahoney's Blogs - Color Correcting, Deep Focus, Bright Sunlight and Classic Cruisers!

For landscape shots, just focus your lens at the hyperfocal distance.

Check out a split-focus adapter -- basically half a macro lens adapter placed over the end of of your regular lens. You can "fake" deep focus, but you have to allow for some distortion where the half-lens ends. Usually, you hide this against some linear visual element, like a doorway or horizon.

Martin

Thanks guys!