Question for GXR owners about snap focus. When you set the GXR at a particular focus range, say 3 meters, does the GXR automatically set aperture? And if yes, can the user change the aperture setting, or is it locked?
How deep is the DOF generally when in the snap focus mode? Is there a DOF scale telling the user that everything from 3 - 6 meters is in focus or something like that?
I suppose the user has to be a very good distance estimator to use snap focus?
Thanks!
You'd generally want to take control of the aperture when you're using snap focus, either using aperture priority or manual modes, so you can control the depth of field. There is a DOF scale showing anytime you're in snap or manual focus mode (similar to the ones on the X100 and X10, but on the side of the screen rather than the bottom, and without the illusion of accuracy that the Fuji's give you). Just came out of a long discussion about this elsewhere (and a short one here) - the DOF scale on the GXR sounds like its accurate. The DOF scale on the GRD3, however (I don't know about the 4), is WAAAAAAAAAAAY the hell off, leading you to use a much smaller aperture than you need and limiting the use of snap focus to really good light situations if you're actually dumb enough to believe it (as I was).
A lesson I'm learning the hard way is to always check the DOF scale on a camera if you plan to rely on them, because I have yet to find one that's accurate. The ones on the LX5 and X100 are a bit conservative, which is not a bad thing for setting zone focus, but makes it impossible to use for finding the hyperfocal distance. The one on the GRD3 is so far off as to be far worse than useless. It's so bad it should be shot, except that it would be hard to do that without wrecking the whole camera, so maybe just a lethal injection.
I have to turn my attention to the X10 on this question soon, because I use the DOF scale for zone focus a lot, and I think it's pretty far off also and you need to know this. Bottom line - to use any sort of zone focus (whether through Ricohs snap system or just setting it up manually) you need to really get to know your camera. Go to DOFmaster and make a DOF table for a bunch off apertures and focal lengths to get a feel for what it
should be able to do, and then go use it enough to get a feel for what it really can do in the field.
The idea of any sort of zone focus system, which snap focus is just a shortcut for, is to shoot with a large enough area in focus, that you DON'T need to be a great distance estimator. If you know, for example, that an area between 3 and 15 feet is in focus, you're in good shape for a lot of close street shooting because you
don't have to worry much about focus on a shot by shot basis. The larger sensor on the GXR limits the DOF and makes snap focus mostly useful in pretty good light. The small sensor on the GRD3/4 makes snap focus useable in nearly any conditions, because you have pretty good DOF even with the aperture wide open. After looking at the capabilities of both cameras in this regard waaaay too carefully over the past couple of days, I've concluded I'm not gonna get a GXR, but I might upgrade the GRD from the 3 to the 4 to get what appears to bean extra stop of sensitivity out of the sensor - to be able to shoot at 1600 rather than limit myself to 800 as I do with the 3.
The only time I use zone focus is shooting on the street or maybe shooting fast moving kids at play within a defined area, where you don't want to have to take the time to focus each shot. If I wasn't into street photography, I seriously doubt I'd ever use snap/zone focus. It made more sense for more applications in the days before auto-focus, but with today's cameras, I think it's a pretty specialized tool.
-Ray