Getting Shallow DOF in DVX100

[Andrew Glassner]

Hello everyone!

I'm getting used to my new DVX100 (the US version), and loving it so far. But I'm having trouble getting a shallow depth of field from it.

To play with depth of field, I set up three targets in front of the camera (each a white page with concentric black and white circles, black lines of different widths, and black text with characters that had small serifs and other details). The first target was 6 feet in front of the camera, the next 6 feet behind that, and the third 6 feet further away. I poured enough light on the scene that it looked fine even at 1/2000.

Then I set the iris to manual, opened it up all the way, and ran through the manual shutter settings one at a time, manually turning the focus ring to sweep from 0 to 99. For some of the long shutter times (e.g. 1/60), I also ran through a cycle with one of the neutral density filters in the chain. To keep things simple, I used the factory-default scene file setting 1.

The result was not encouraging: sure, things came in and out of focus, but uniformly. I wanted to get the middle target nice and crisp, with the nearer and farther targets looking fuzzy. But my experience through the viewfinder was the same as when I downloaded the tape and watched it on my computer: there was no appreciable depth of field. As I pulled the focus, everything went from fuzzy to clearer, then everything was clear, then it all got fuzzy again.

Can anyone help me unlock the mystery of obtaining a shallow depth of field with the DVX-100?

Thanks!

-Andrew
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Andrew Glassner

[Frank Granovski]

Perhaps try zooming in from afar, with focus set on the subject and the iris opened wide.

[Jeff Donald]

DV Info has an article on DOF here. There is also a fairly extensive thread on DOF here. If you have questions after wading through all the DOF material, feel free to post back.

[Wayne Orr]

There is no secret to getting shallow depth of field with any 1/3" camera, Andrew. There is just the truth, and that is: it ain't gonna happen. You would better spend your energies working on improving your composition and lighting skills, since this is how you will be able to separate your subjects from the background.

For a look at a contemporary movie with deep focus pictures, take (another) look at "Signs." Fabulous composition and lighting by Tak Fujimoto.

If you absolutely must have shallow depth of field, you have to step up to larger size chip cameras, preferably 2/3".

Either that, or every shot set-up you have to have at least twenty feet between your subject and the background. Not very handy, especially with interiors.

[Charles Papert]

I just worked with this camera for the first time, and was able to achieve a few shallow focus shots using the macro function (here are the results). p.s. Mac users will need to hold down the "control" key and select "download to disk" to view the film on Windows Media Player, unfortunately.

The camera will allow you to go into macro for the first 10mm or so of the zoom range (from the wide angle end). The indicator in the viewfinder will let you know if you have zoomed in too far and are no longer in macro. Focusing on close foreground while in macro will deliver the soft focus in the background you are looking for.

Otherwise, the camera is no more capable of delivering a shallow depth of field than any other DV camera with the same size chips.

[Andrew Glassner]

Thank you, everyone. That's great information. It's very helpful to know what the camera's built-in limits are, and not spend a lot of additional time trying to figure out how to make it do what it isn't designed to do.

I've thought about some post-processing tricks (e.g. if the camera and lighting are fixed, you can do some image processing to distinguish moving elements from non-moving elements, and selectively blur just one or the other). But except for close-foreground shots, I think the more general solution here, as Wayne and Charles have both observed, is to use lighting and composition skills to bring about the same control over the viewer's eye that I'd otherwise use DOF for.

As the wise man said, constraints promote creativity!

-Andrew

[Wayne Orr]

Well, Andrew, aren't you the reasonable fellow. How refreshing. Here is a link to a short MOS clip that features 3 ladies you may recognize. Look at the last two. I did some post blur work on the backgrounds because I wanted to see what all it would entail. Exactly what you were talking about. It is definitely time consuming for anything of length. http://www.digitalprods.com/girls.htm
Be sure to pause the clip to study the look, as they are rather short.

[Tom Hardwick]

Wayne speaks the unpaletable truth: that using 1/3" chips and very short focal length lenses means depth of field control is difficult. Especially for the Panasonic, as its longest focal length is just 45mm.

Look at it this way. If you fitted a 45mm lens to your 35mm still camera you'd also struggle to get a differential focus effect. There's no difference with a video camera - the laws of optics still apply. Only real solution is to invest in a 2x converter, that way you'll end up with a 90mm f2.8 lens. Now you can start to take differential focus seriously.

Don't be tempted to use digital zoom by the way. Although the effective focal length has changed, the depth of field remains as it was at the longest (optical) focal length.

tom.

[Andre De Clercq]

Lens focal length doesn't change DOF for a fixed subject size. Only F-number and CCD size can solve this problem.

[Tom Hardwick]

Explain again Andre. We've all seen those Nikon lens advertising shots where the model sits on a park bench and she's shot with 10 different focal lengths ranging from 14mm up to 800mm. She's the same size in each frame, yet the differential focus in the 800mm shot is very noticeable and in the 14mm shot it's non-existant. So I don't believe you. :-)

tom.

[Jeff Donald]

If you change the distance from CCD (film) to subject, you've changed perspective and angle of view. But DOF will not change if the subject size (target) remains the same size. This is explained in this article on DV Info and this thread.

[Tom Hardwick]

Can I get back to the real world Jeff and Andre and have a full half hour of argument? I read your words and hear what you're saying, that the DOF will not change if the subject size (target) remains the same size. Look again at my example of the girl on the bench (the target). She remains the same size in all the shots. Are you saying the DOF is the same in all of them? A casual glance at the photos is enough to tell that this is not so.

tom.

[Jeff Donald]

Tom,

Where is the link to your example? I'd like to take a look at it.

Jeff

[Tom Hardwick]

er - it's not a link, it's a Nikon lens brochure that I have right here in my hands.

[Jeff Donald]

It is difficult to comment on something I can not see. However, I have shot those lens comparisons in the past. I did one for a major 3rd party lens manufacture and recently for my students (I teach 35mm still photography and digital photography). You will probably notice that there is very little behind your subject to go in or out of focus. Because there is nothing immediately behind the subject, DOF appears to be shallow in most shots of a comparison nature. At least that’s the way mine turn out.