The Ultimate Depth of Field Skinny

[Bob Harotunian]

Jason,
It's called shallow depth of field. There's a nice explanation here: http://www.dvcreators.net/media/depthoffield.html

[Chris Hurd]

Better yet, check out Jeff Donald's comprehensive Ultimate Depth-of-Field Skinny on our own site. Hope this helps,

[James Emory]

If you move farther from your subject, like 25-30 ft, and then zoom in on your subject, it will be sharp and the background will be soft to give you the desired effect. If you move back too much, everything will be sharp defeating the effect.

[Jason Balich]

Thanks guys!!

Im a newbee and working on learning this camera and how to ge the desired effects.

That flash tutorial of depth of field was excellent. Thanks again!!

[Jason Balich]

Still having problems using the GL2 to get this effect. It seems i have to do it in post with mask and gaussian blur.

ROTO-time or is there a setting on the camera im forgetting?

[Bob Harotunian]

Jason,

Don't laugh, but one place I found useful to practice this effect was at the local zoo. Keep your camera on manual exposure and manual focus, keep f stop low as possible (aperature wide open) and if outdoors you may need to use the ND filter to lower exposure. Zoom in on subject, adjust focus, reframe and background should be out of focus.

HTH
Bob

[Jason Balich]

ill take a trip to the zoo definetly b4 the mosquitoes come out here in toronto to much with the nasty "west nile viris" thats going around.

In regards to your advice im not sur ewhat u mean when u say reframe.

When i zoom in and focus on the object..do i then zoom out which is called "reframe"?

[Bob Harotunian]

That's right, zoom out a little but not all the way or you'll lose the shallow depth of field.

[Jason Balich]

thanks for your patience. I appreciate all insight.

[Jeff Donald]

Controlling your aperture will give you the most control over DOF. You must force the aperture to be wide open(F1.6, F2, or F2.8). Try to avoid anything higher than F2.8. Use the built in ND filter, set gain to minimum (if you can control gain). Read the article Chris Hurd pointed you to. Most people don't understand DOF. Backing up and zooming in will not give you a shallow DOF. That's why it's not working for you. Backing up increases DOF, zooming in decreases DOF. The net result is no change in DOF. Only the aperture will give you control over DOF.

[Jason Balich]

THat is the ticket!

Ill try it tonight at home. Ill write you back 2morro.

Thanks for your tips. I love details like that!

[Ken Tanaka]

When all else fails optically and you just have to have that background blurred "silking" is a trick that is sometimes applied in video shooting. Silking is basically the placement of some type of translucent material (sheer fabric, plastic, et.al.), usually stretched on a frame, behind your subjects to blur the background. It can be a very time-consuming production process to ensure that the material is invisible in the shot. Lighting and material selection are critical. But it can be very effective on small, controlled scenes.

[Wayne Orr]

Other than for Ken's last post, I get the feeling you guys are leading Jason to believe that there is actually something he can do to create a narrow depth of field with a quarter inch chip camera, and that simply is not going to happen in a real world situation. (I am not talking about shooting extreme close-ups of the head of a coin) Here are some real world figures to consider:

Using my PD150, (a one third inch camera with LESS depth of field than the Canon at one quarter inch), I shoot a talking head at fifteen feet with a focal length of 12mm at f/2.8. If I were shooting this in 35mm, the lens equivalent would be about 85mm (a good portrait lens). The depth of field in 35mm terms would be: near limit, 14.35 feet. Far limit would be 15.7 feet, for a total depth of field range of a mere 1.34 feet. Great for those who like narrow depth of field. Now back to the PD150 with one third inch chips.

The near focus is 7.5 feet and the far limit is (are you sitting down?) 1015.94 feet! Yipes. If you stop down to 1.4 you can get the limit down to around forty feet, but you will still have most background objects in focus in normal interiors. And remember, that far limit does not mean things are immediately a blur in the background; rather they slowly fall off focus. And f1.4 can cause other problems, since it is certainly not the best aperature to shoot at with a zoom lens.

Where do I get these outrageous numbers? A very handy depth of field guide from Panavision, to be found at: http://www.panavision.co.nz/kbase/op...alcFOVform.asp
There simply is no way to get around the numbers. But I am sure someone will find a way to argue the point.

[Jeff Donald]

The Panavision site uses non-standard values for CoC. The use of non-standard numbers gives exaggerated values. None the less, Wayne is correct in asserting that shallow DOF is difficult to achieve. One method is to use physical effects as Ken suggests.

Another method is to cheat your focus. Wayne's example assumes that you focus on your subject at a distance of 15 feet from the camera. But if you deliberately focus in front of your subject, say 8 feet away, (with your subject still 15 feet from the camera) DOF is from about 5 feet to 16.8 feet. This results in anything beyond 17 feet being out of focus (even with their non standard numbers). If you opened the lens to F1.4 and deliberately focused at 11 feet (with your subject at 15 feet) DOF is from 8 to 17 feet. This is not extremely shallow, but you can knock the background out of focus and a portion of the foreground.

This technique will not be very helpful for rack focus etc. But it is one method to use to get a more limited DOF with the tools you already have.

[Wayne Orr]

That is a pretty sophisticated regimen you are recommending, Jeff. It assumes you have a lens with incremental markings for focus, something I haven't seen on the cameras we are talking about. Even the DVX100 would only give you an approximation of the exact distances you are talking about. And that camera won't iris to f1.4, nor will most of the cameras. Even the PD150 will only go to f1.6, and certainly does not perform optimally at that stop. And again, as I mentioned earlier, the background does not become the classic "blur" that most young filmmakers are interested in, but rather, slowly goes further out of focus as the background distance from the subject increases. Very difficult to make this happen in an interior setting.

Basically, I am saying that with small chip cameras, shallow depth of field is not difficult to achieve, it is virtually impossible under normal shooting conditions. The problem is that some of us are creating a false impression that maybe, just maybe, if you wish really hard, and knew the secret tricks, that you will be able to get blurry backgrounds with these cameras, and it simply is not going to happen.

I wish there was as much interest in proper lighting techniques, composition, and art direction. But of course these require study and constant practice and offer no "magic bullet" to master. Deep focus is not the enemy to creating striking images. See the movie "Signs" for some great examples in a contemporary film. Additionally look up chiaroscuro.