View Full Version : Urgent advice on focus technique

Phil Brown
05-22-2005, 05:17 AM
I am filming a piece tomorrow night that will be released as a tv documentary.

Will need to follow the interviewer through a backstage tv set, to various points where he will stop and interview guests.

Can anyone advise the best way to keep focus. My plan is to keep zoomed out to zero and set focus at MF99 for walking shots, and then to between MF35-50 for the interview closeups. I'm worried that I will overshoot the focus points under pressure resulting in a second or so of crappy focus during the closeups. Also need to pan occasionally between interviewer and interviewee.

All of the interviews I have shot so far were fixed subjects. Should I just use auto focus and take the heat off?

Would appreciate your expert opinions.


05-22-2005, 07:36 AM
First, don't use MF99 -- that's actually "past infinity". Use MF95 for infinity. And you probably won't need infinity anyway -- Z00 and MF80 would probably be a better choice, as (depending on your aperture) the far end of the DOF will probably stretch close to infinity anyway.

Do you have a 100A? If so, you can turn on the "peaking" control (EVF DTL); familiarize yourself with how that looks and it can be a great help in grabbing manual focus.

Also, you can always use the "push auto" button to have autofocus grab the proper focus point for you, but when you release the button, you're back in manual focus mode. That will get you some of the benefit but will help avoid the "focus hunting" that everyone hates about autofocus.

MF35 would equate to about 1.5 feet away -- really, really close for an interview! MF50 is about 3' away. Use the focus chart and familiarize yourself with what distances equate to what numbers, and you'll stand a better chance of getting proper focus in situations like you're describing.

Phil Brown
05-22-2005, 07:54 AM
Thanks Barry,

Yes I'm using the 100A and practicing with the EVF DTL on.

Just reads your other post on DOF which I think has answered everything for me. If I have this right - if there is enough light that I can get to say F8.0 or above, zoom to F95 and set the set focus on around F50 (found the chart), I should have a huge range of DOF and shouldn't need to worry at all.

I am concerned about the amount of light backstage - might have force me to open up the aperture and shorten the DOF - but thats a great tip about a quick push of the auto button to grab focus.

Brillaint Barry - you're a legend, much appreciated.


Phil Brown
05-22-2005, 08:08 AM
Correction - getting confused with settings - Zoom to Z00, MF50 for closeups.

05-22-2005, 08:38 PM
Is the focus chart in your book Barry?

05-22-2005, 10:06 PM
Yes, the book has a version of it, which I went through and verified, changed the infinity point, and updated for the 100A to add the new close-focus numbers from 37 to 49.

Frizzle Fry
05-23-2005, 07:26 AM
wouldn't it be cool if the camera had a built-in range finder with on-screen display? i'm a terrible judge of distance, and in a moving shot if you had constant feedback about distance to subject, that would be a great help. actually, if the camera "knew" distance to subject, it could calculate based on a focus chart and "recommend" an MF number.

or am i dreaming?

05-23-2005, 07:32 AM
You may find yourself more challenged at getting the exposure right in a moving/following situation. If it was me I would be in AF mode so I could focus on framing, shooting, audio, and exposure. But I am a rookie, and can only do so much at one time. :)

Phil Brown
05-24-2005, 12:14 PM

Thanks for the help from you all.

I shot just over 2 hrs of footage and the director is happy with about 70%. Had some very low light backstage in the Greenroom that was simply impossible to shoot with real quality but the rest was sensational.

Huge thanks to Barry Green for his advice and tips - couldn't have done it without him.

Was able to maintin great focus throughout the shoot, and surprisingly, was able to stay calm throughout the totally handheld shoot.

Think a big part of the success was after getting clear on DOF (Barry's tutorial is awesome) I rehearsed the moves and focus pulls probably a hundered times in my apartment before going to the location. When it all happened, and it happened really fast, I just seemed to go into auto-pilot.

I white balanced almost every setup (was cought out a couple of times), and then by keeping zoomed out, and focus at around 80 for wide shots and 47-50 for close-ups was able to concentrate on scene composition and movement.

I used Barry's tip of touching the Auto button in close-ups to momentarily engage and then dis-engage the Auto Focus. This made some minor focus adjustments in what was a very active environment - great tip and created some really sharp close-ups.

As I moved from areas of wildly varying lighting with no rehearsal possible I used the same technique to fine-tune iris setting. I think the end result was acceptable for a high movement shoot in a backstage environment.

It's tough controlling light, focus, composition, and sound - (had a Lav and Shotgun pumping through the headphones), but I think the editors will have some great material to work with.

I have sent a personal note of thanks to Barry, but just to re-iterate one point, I can't under-estimate the value of this brotherhood of like minded individuals who are willing to help out a friend in need - thanks to you all.

Phil Brown

05-24-2005, 12:42 PM
Good recap.