reduce depth of field on Canon HV20

[Steve Brady]

Originally Posted by Robert Ducon

Even then Steve, Pieter is right. The fully open Iris on the HV20 is still shaped like a diamond - it only consists of four-blades. So Pieter, that's the best you'll get! And, it's not bad, really.

Like I said, the trick is to lock the aperture with the camera zoomed out fully. If you lock the aperture with the camera zoomed in at all, you can't get a fully open iris. This is straight out of my camera (it's the Num Lock light on my keyboard):

[Robert Ducon]

I stand corrected! Now that I think of it, I've gotten an image similar to that too, but the focus was so far out that it was just pretty colours (shot at night, street lights, etc).

[Pieter Jongerius]

Hi Steve&Robert,
thanks voor 'zooming in' on my relatively OT statement there. Helps me a lot!
Pieter
(ps - and I learned a new word: bokeh ;)

[Loney Childress]

I too would love to be able to do DOF effects more naturally, but it costs so dang much. In a short movie I made (before buying my HV20) I did the green screen trick. I think it looks alright.

Here's a link, not to my movie but a short demo of some of the effects in my movie. You'll see one is a DOF effect using green screen. I don't think it looks half bad.

http://youtube.com/watch?v=AXec4XjmtHE

[Rob Gregory-Browne]

For anyone who gets hung up on depth of field, I urge you to see Orson Welles's Touch of Evil.

[Michael Jouravlev]

Zooming in does not produce shallower DOF if the subject takes up the same portion of the screen.

[Chris Hurd]

Actually yes, technically this is indeed true. Zooming in will in fact produce a shallower depth of field. However this technique for decreasing depth of field is not all that useful because the subject size obviously changes as focal length changes. For a full explanation, see our definitive article "The Ultimate Depth-of-Field Skinny" by Jeff Donald, located at http://www.dvinfo.net/articles/optics/dofskinny.php -- hope this helps,

[Daniel Browning]

You are both correct.

Originally Posted by Michael Jouravlev

Zooming in does not produce shallower DOF if the subject takes up the same portion of the screen.

Michael, you're saying that DoF does not change if the operator moves the camera so that the framing is the same, no matter the focal length.

Originally Posted by Chris Hurd

Zooming in will in fact produce a shallower depth of field...[but]...the subject size changes as focal length changes.

Chris, you're saying that the DoF will change if the operateor does not move the camera.

It's important to note the difference, because if a shot is framed the same way at wide angle and telephoto, the telephoto shot will yeild more diffuse background blur due to magnification, even though the DoF is the same.

[Brad Mirman]

I did a quick test on DOF for the HV 20. You can view it here:

http://www.vimeo.com/393169

Make sure to select Full Screen to see detail.

Hope it helps.

Brad

[Rob Gregory-Browne]

Hey, Brad, thanks for the DOF test on the HV20. The image is gorgeous.

I'm curious -- are you the same Brad Mirman who wrote Resurrection? One of the creepiest serial killer movies of all time.

rgb