dof with stock lenses

B

bwwd

Veteran
I have a question about that, my camcorder has 49mm lens 1.6 and on zoom in i can get some quite nice dof shots , but i wondering what determines how quickly i can get nice depth of field ? If my camcorder would have for example 30mm instead of 49 then i would have much wider field and on zoom in i would have bigger field of view and the same DOF like on my current camcorder right (if sensors would be the same ones)?
You dont have to zoom in all the way to get nice DOF its actually not even half through zoom in and i can see some DOF when i come closer ,but i have only49mm so my field of view isnt so big.
I know that we lose some FOV on zoomin and our wide angle 28 or 30mm lens becomes telephoto ,i would like to check this some day on camcorder with interchangeable lenses like xl-1 ,anybody tried that ?
 
So I'm not totally sure what you said, but I'll try to say what determines depth of field.

First off, there is no such thing as 'nice' depth of field, or even just DoF. It's either shallow or deep.

Second, sensor size has no impact on DoF. That is a function of the lens only; aperture, focal length and maybe the individual lesn. The reason larger sensor sizes result in shallow DoF is that the focal length to get the same scene changes.

So having a larger focal length will result in shallow DoF in the same frame. You mentioned lengths in your post, so I'll assume that has something to do with what you're saying.

Once you get long enough lenses, such as those built for 35mm image planes, aperture becomes the important deciding factor. Smaller numbers (open lenses) result in shallower depth of field.

Distance from the subject also enters into this. Generally, the closer your subject to the camera the lower the depth of field, but the shape of the scene tends to get other odd effects that make it less of a consideration. That balances out the focal length thing a little.

There's a calculator here:
http://www.dofmaster.com/dofjs.html
That can simulate whatever you may want to find out.
 
Ok i explain it like that , here is the pic:
http://img516.imageshack.us/img516/4351/clipboard2.png
It has some amount of DOF (blurred out background) but not much,still its enough for me to get some interesting shots from time to time, my camcorder is zoomed in halfway through ,i have only face visible to eyebrows but i would like to have the same amount of blur behind me and larger field of view so i could see my whole head but still have this blur behind me.
So what i would need to change in camcorder to get that without moving my camcorder away from the subject ? now it has 49mm and 1.6 so which lens would give me bigger chance to get bigger FOV with background blur from the same distance ? OR only bigger sensor size would do that ?
 
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