Autofocus or Manual Focus ?

[Randall_Oelerich]

Standard rule was use manual focus for filming with DSLR, which I do, but my DSLR is about five years old. I am wondering with the newest batch of 4k DSLRs which far more sophisticated autofocus, can one use autofocus on newer DSLRs for making low budget films? Are the cameras fast enough on autofocus for that to work? Or is the rule still to turn off autofocus?

 

[Michael Carter]

I don't know that there's a "rule", more that useable AF hasn't really been that hot for things other than events and news type shooting.

I got an NX1 and a native zoom, but I mainly put Nikkors on it. I've played with the AF and OIS and used it for some shots. The NX1 is pretty amazing with AF for video, but you have to really watch your focus point. I've used it on a steadicam and had some really useable results, though I was shooting pretty wide (16mm). But I shot at more like F3.5 vs. the usual 5.6 so there was some focusing needed.

I don't know that I'd use it for a precise in-shot focus pull; there are some examples on EOSHD where a guy shooting a spot with racing cyclists used an NX1 with a handheld gimbal and AF from a chase car and it looks amazing; he said he couldn't have gotten many shots without it and it kept the takes down - but this was tracking a fairly close subject that stayed in the same area of the frame and the camera had to deal with smaller adjustments. The NX1 will really track well in good light if you keep the subject in the focus area, and you can touch the screen for focus. It can be pretty impressive (never played with Canon's AF cameras) but something you'd want to test and reserve it for special shots.

If you're going to rely on AF for an important shot, I'd want to have a big monitor (bigger than 7", more like a 20" HDTV or something) and triple check playback before you wrapped the shot.

I've used AF on cranes to set initial focus point sometimes, but more often pulled focus on those moved.

 

[Rainer]

Hi Randall, yes, they're fast enough to maintain focus for events, really great for bride walking down the aisle, news, documentary. Typically, in film you need the control, you don't want to let the camera choose where to focus, even where you need to shift: set focus on first mark, put indicator on follow focus. Set focus on second mark, put second indicator on follow focus. Shoot scene. Having live AF wouldn't help.

 

[Samuel H]

My Sony RX100 IV has pretty good AF... when it works. At 1080p at up-to-60fps, it has face detection, and if it locks on a face it will track it very well (actually better than I can most of the time). But if it doesn't lock on the face (subject not looking at the camera, hair covering one eye, non-human subject, etc), then it's either closest-point-to-the-camera, which I don't like at all, or center focus, which may work or not depending on the shot.

Since I moved to this camera, I've used AF around 60% of the time, pre-shot AF lock around 30% of the time, and manual focus the remaining 10%.