Active AutoFocus

[ppershan]

Although many sources describe both ultrasonic and IF active autofocus mechanisms the only camera that I have been able to find that had either one of these is the Polaroid SX-70 (and its Polaroid sisters).

Are there any other camera's that have (had) a active autofocus?

Thanks

ppershan

[JimC]

Hey ppershan.

Welcome to Steve's

You posted this in our Contact Steve's forum, which is designed for feedback, concerns or comments about Steve's.

So that you'll be more likely to get responses from members that kep track of different Autofocus Systems cameras are using, I'll move this down to our General Discussion Forum for you.

If you're looking for a new camera (versus just wanting to discuss different Autofocus Systems), let us know, and I'll move the thread to our What Camera Should I Buy Forum instead (which is setup for that type of discussion to help members find a camera that meets their needs).

What you refer to as "Active Aufofocus" is also puzzling, and I'm assuming you mean the Sonar type AF used by that Polaroid. That's a rather unique AF system.

For the most part, there are two different AF systems in use now by most cameras..... One is Contract Detect Aurofocus, and the other is Phase Detect Autofocus. Neither is an "Active" (generation a signal of some kind) type of focus system.

Some cameras have also used an Infrared AF System. But, you don't see that in Digital Cameras very often anymore. As for Ultrasonic AF, nope, I'm not aware of any current cameras that use that technique (or would I see a need for that type of Autofocus System).

[tclune]

Originally Posted by JimC

For the most part, there are two different AF systems in use now by most cameras..... One is Contract Detect Aurofocus...

I'm pretty sure that's only used by lawyers...

[TCav]

See http://en.wikipedia.org/wiki/Autofocus#Active

[ppershan]

The reason for my post was that I am preparing a course on cameras and a number of references, (see for example Jacobson, R. E. (2000). The manual of photography : photographic and digital imaging, Oxford ; Boston, MA: Focal Press., p151) writes about 'active ranging systems' that use either sound or IR.

I agree that unless one is trying to take IR photographs in the dark there doesn't seem to be a need for this type of device.

Thanks for your input.

ppershan

[TCav]

Originally Posted by ppershan

I agree that unless one is trying to take IR photographs in the dark there doesn't seem to be a need for this type of device.

From the Wikipedia article that I provided a link to:

... infrared light is usually used to triangulate the distance to the subject. Compact cameras including the Nikon 35TiQD and 28TiQD, the Canon AF35M, and the Contax T2 and T3, as well as early video cameras, used this system.