Depth of Field in Digicams is ~5x bigger than w/ a 35mm

I was amazed to see this too.

Have a look at these sites if you dont' believe me:

http://www.wrotniak.net/photo/dof/

http://www.cs.mtu.edu/... .../User-Guide/990/EXPOSURE/EV-depth-of-field.html

http://www.geocities.com/hapm/dof.html .

http://www.luminous-landscape.com/dof.htm

Isn't that nutz??? That means that a pic shot at f2.8 on my coolpix will have roughly the same DOF as one shot at f16 on my Nikonos...

As an underwater photographer, I look at this as a DISTINCT ADVANTAGE over film.

This finally explains to me why my coolpix in automatic mode selects such low f-stops when shooting underwater with a strobe. I think the camera's firmware is hardwired to select low stop-high speed over high stop - low speed. That's why I have to shoot in manual mode w/ the external strobe.

Cheers

James

[Edited on 12-28-2001 by jamesw]

Digital cameras with larger sensor sizes (like the housed D30 we were using in Kona) don't have such a severe "problem." (it says this in the articles you link to, but I just wanted to repeat it here, for clarification.

I guess it can be viewed as a benefit to have greater depth of field, but I'd rather have the option to shorten depth of field to make subjects stand out more.

We can always buy bigger strobes for more light.

Yep...once the CCD's hit 1 to 1 I guess it's back to "normal."

Cheers

James

I have 2 issues with this.

If you look at the equations -

It is not actually the sensor size, which causes this difference, but the actual focal length of the lenses. In fact, the small sensor size works against DOF, since the whole image is smaller, so the allowable circle of confusion must be smaller, to get "acceptable" focus.

But the actual focal lengths, (as opposed to the "35mm equiv focal lengths"), is the over-riding factor, since it contributes as a square factor, towards greater DOF...

But in practice, I don't see it! F8 at about 3 or 4 to 1, and I don't seem to get the DOF I would get at f45

But, I don't have my n90s and nikor 100 macro lens here to compare with...

What do you all find?

Don