On Aug 8, 2005, at 9:12 AM, Joseph Tainter wrote:
It wouldn't be difficult for camera makers to build a DOF calculator into a camera and have a digital display of the DOF 9for the current focal length and aperture settings) on the rear-panel LCD.
It shouldn't be difficult: all you need is an approximation anyway. (That's all the older lens markings are as it is.)
Wow. Interesting idea. Now that cameras are computers, how about a function that automatically sets the lens to the hyperfocal point for a given focal length and aperture? Otherwise setting hyperfocal distance manually on newer lenses is very difficult, because a small turn of the focusing ring makes such a big difference in the focus, and the distances that are marked are so far apart.
This kind of function has been on various cameras already. Minolta had an automate hyperfocal program in plug-in cards for their Maxxum line.
Canon supports a different twist: the AE-Depth program setting in the 10D (p 88 in the manual, if you happen to have the PDF file). Target all the subjects you want to have in focus across the AF sensor array, the camera will attempt to use focus and aperture settings to cover as many of them as it's possible to achieve given the specific focal length and proper exposure requirements. The focus points will flash on all the subject entities it was able to encompass, and warn you if the DoF you desired was too much to achieve.
The last numerical distance on the DA 16-45 is 2m/7ft. After that the next marking is infinity. How do you set a hyperfocal distance of 3m on this lens?
You fuss with it... ;-)
I don't find DOF preview useful. It just makes the screen too dark.
If I'm really really being persnickety and working from a tripod, DoF preview works well. I carry a darkcloth so I can see the focusing screen. Normally, though, I am looking for OOF rendering with DoF preview and working at fairly large apertures, to see the difference between f/2 and f/5.6 for instance. I'm not generally looking to estimate the focus zone this way.
Godfrey
