Depth of Field
 

Hi all,

Some time ago there were some rumors that the fx1 had a shallower depth of field as opposed to other 1/3" camera's, because of the extra pixels. Others have said that pixels make no difference, it's only the size of the ccd that matters, so that way the DOF should be identical to a PD-170 or DVX100a. Without losing ourselves in a theoretical discussion again, could anyone who has a fx1 as well as the dispose of another 1/3" camera test this? It should be done with the camera's equally close to a subject and with the same focal length. Than we can have a decisive answer to this matter.

Thanks in advance,

Steven

I may be mistaken
 

But from my photgraphic theory I recall that DOF is purely a fuction of flens focal length and appeture. Nothing to do with CCD / Film size other than this is used to describe the focal length of the lens in terms of films size ratio.

Tony

Tony is correct. The DOF is established in the lens, not by the chip.

The only effect that a higher-resolution chip could have on DOF would be an ability to resolve the image just a little tiny bit more before an area crosses the threshold from "in focus" to "out of focus". So theoretically a higher-resolution chip could have a microscopically DEEPER depth of field, but it will most certainly not exhibit shallower DOF.

We just finished an extensive comparison of the FX1, DVX and XL2 all side-by-side, and are working on compiling the results. Short answer: this talk of the Sony having shallower DOF than the others is completely unwarranted. It does not defy the laws of optics, and for all practical purposes it exhibits identical DOF to the Canon and Panasonic (when at identical focal lengths, aperture, and distance to subject).

The XL2 is capable of the shallowest DOF of the three, by virtue of its longer lens, if you can stage your framing such that you're able to take advantage of that longer focal length.

Thanks Barry for clearing that up. Now I guess we'll have to wait until P+S will release a mini35 for the fx1. Or maybe movietube.

We'll see.

Steven

PS: what were the rest of the outcomes on the comparison test?

Bigger chip video cameras and bigger negative film cameras have shallower depth of field for the equivalent focal lengths. The FX1 and Z1 will have even more depth of field when shooting 4:3 than it does in 16:9 because it is, in effect, using a smaller chip (just as the DSR500/570 do when they crop the edges for a 4:3).

Depth of field is controlled on a particular camera by the lens, but how shallow your depth of field can be at a particular aperture and focal length is determined by your imager size...otherwise P&S's mini-35 would never have been necessary...

When we shot today, I had to step back 6 feet with the camera, then move an actor back 8 feet, zoom in (which pulled the actor in, visually) and do a rack focus. It was tough, very deep depth of field.

heath

Imager size controls field of view, which dictates the appropriate focal length for the lens. But it's the focal length that gives the shallow DOF look.

The mini35 allows you to use longer-focal-length lenses. That's why it delivers shallower DOF.

The FX1 and Z1 have the same image size at the same focal length as all other 1/3" cameras do, so their DOF is identical as all other 1/3" cameras when at the same focal length and same f-stop.

to put things into perspective and to be consistent with all other 1/3" CCD (which are 4:3)

the FX1 CCD is wider and equates to a letterbox of a 1/2.7" CCD

This gives a wider FOV and means more Bokeh for the same DOF as other 1/3" CCD