Zoom out vs shallow dof

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plainman007

Well-known member
Hi everyone,

Most of the general consesus is to zoom out as far as possible and move close to a subject in order to eliminate camera shake. But when we need Shalllow DOF we are asked to move in as close to the subject and open up the iris as far as we can. Bottom line mostly is that when we film an object up close is when we want to show a shallow DOF. But sometimes we want to focus on something far a show DOF blur on closer objects. How does one handle zoom settings for these kind of DOF shots ? Does one have to shoot fully zoomed out ? or vice versa ? And how will this affect camera shake ?

Simply put ,,,suppose i wanted to film someones face with the backgrnd buildings etc blurred. What are the basic rules ? Now if that person was walking and we had to follow while maintaining the same DOF blurred backgrnd ...then what do we do ? Is it possible to zoom out fully wide while doing this type of moving shot in order to suppress camera shake and if we do wil it affect the DOF effect that we are trying to achieve ??
 
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I'm not an expert but I'd say it all depends on the camera and lenses. DOF has to do with aperture settings, focal length and also size of chip/negative. Don't know what kind of lens you are using so I don't know what exactly fully zoomed out would mean. When shooting 35mm film with proper cine-lenses, a shallow DOF is not that hard to achieve. Even wide angle lenses produce nice blurry backgrounds.

But I'm assuming that you want to know how to get DOF out of some low-end digtial camera. My answer here would be: You're in trouble! If you want shallow depth of field, you need a longer focal length. On a zoom lens that would mean the further you zoom in the longer the focal length. So if you want to achieve DOF in DV you would have to step back and zoom in. If camera shake is a problem... put it on a dolly. Also, a large distance between the subject and the background would help with DOF, but if you're in smaller spaces this will be difficult.

The rule would be: Low-end gear = compremises (you can choose to film without cool DOF or to not film at all..) It frustrated the hell out of me in filmschool, but that's life...
 
Wide angle = deep DOF. Telephoto = shallow DOF.

You're asking a coin to be heads-up and tails-up at the same time. Can't be both, you'd have to choose one or the other.
 
Barry_Green said:
Wide angle = deep DOF. Telephoto = shallow DOF.

You're asking a coin to be heads-up and tails-up at the same time. Can't be both, you'd have to choose one or the other.
Click to expand...

Technically he could use a wide prime lens with a large aperture, I suppose.
 
my Canon FD 24mm F2.8 surprisingly has a relativly SHDOF, and its pretty wide angle. Try a 35 adpter, and that lens. IT kinda gives that coin on both sides situation. Infact its image looks "synthetic" that the background is out of focus, on wideangle two person shots.
 
There are 4 elements to depth of field. One is focal length (how far you are zoomed in or out),. The second is Aperture. The third is ccd/negative size and the fourth is FOCAL DISTANCE.

i.e. you are filming a man with a 50mm lens on a 16mm camera (roughly equivelant to a 2/3 inch ccd) and shooting at t5.6 .

If the man is 9' away from the camera everything from 7' to 12' will be in focus. If the man was 3' away from the camera the depth of field would only be from 2' 9" to 3' 4".

The same lens and stop but very different depth's of field.
 
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