Auto Focus: Continuous

[Paul Whittington]

Hi... I've been trying to get the 'Continuous' mode of 'Auto Focus' on my Scarlet to work without much luck. All it seems to do is just rack back and forth going in and out of focus - sometimes it will find focus but just for a moment then start racking again... I even tried it using plenty of light as the manual suggests and still no luck. Was wondering if anyone else has experienced this problem or could tell me if I'm doing something wrong. Or, if it is just the way the camera is, I would love to know of any workarounds or alternatives people have come up with as a substitute for using Continuous... I have a particular shot I want to shoot where the camera is about a foot from the floor facing straight down, then slowly rises up to about 8 or 9 feet on a jib, wide angle the whole time, with focus locked on the floor for the entire shot. Because I am using a jib I will not be able to focus pull... thanks in advance for any help you can offer.

 

[Mark Phelan]

I don't think you're going to have much luck with that using the continuous focus mode. Sure, it seems like it would work, but in reality it'll do exactly what you describe, hunt for focus.

My suggestion is to use the rack focus feature and time your jib move to coordinate with the racking of the lens. But it won't be perfect, you'll need several attempts to get one right. This is where Foolcontrol comes in handy since the camera is on a jib. You'll be as busy as a one-armed paper-hanger, but you could pull it off if everything aligns itself.

 

[Paul Russell]

It never works. Red's focusing system relies on contrast (as opposed to Canon's Phase Difference system) and you'll find it hunts to the point that it's unusable.
Nice try by Red, but not workable, especially if you are in a 'one chance to get the shot' scenario.

 

[Werner Jauch]

Just in case OP is not aware, if using Canon lenses, redmote allows remote focus adjustment

 

[Jacek Zakowicz]

There are few options indeed.
But only one really works.
you know what it is haha.....

 

[Maik Müller]

Hi... I've been trying to get the 'Continuous' mode of 'Auto Focus' on my Scarlet to work without much luck. All it seems to do is just rack back and forth going in and out of focus - sometimes it will find focus but just for a moment then start racking again... I even tried it using plenty of light as the manual suggests and still no luck. Was wondering if anyone else has experienced this problem or could tell me if I'm doing something wrong. Or, if it is just the way the camera is, I would love to know of any workarounds or alternatives people have come up with as a substitute for using Continuous... I have a particular shot I want to shoot where the camera is about a foot from the floor facing straight down, then slowly rises up to about 8 or 9 feet on a jib, wide angle the whole time, with focus locked on the floor for the entire shot. Because I am using a jib I will not be able to focus pull... thanks in advance for any help you can offer.

Continuous is a thing of luck. It's not reliable. As much as the AF-performance has improved over the years, it's still a Contrast-based AF. Think 5D in liveview (noticable better, but still limited). As such it will never get where the DualPixel-stuff from Canon is, or what Sony can do with their A7*-cameras.

Overall, to improve the performance of RED's AF you can do some things:
- focus on a contrasty target with fine details + light
- wide-angle with iris closed (deeper DOF) - it should be a supported lens
- shorter exposure-time (=sharper images)
- higher fps might help too
- don't forget to enable enhanced AF

With all this in mind the AF on RED is usable and can be very helpful. Especially to get initial focus or focus on demand during a shot. Continuous on the other hand... well i wasn't very successful with that one, especially when the target moves in depth.

For your specific shot i would try the REDMOTE or SIDEKICK (you can focus via the wheel) and the RACKFOCUS feature. You would set the start and end-point and then get the speed aligned with the speed of your jib-move. There will be some trial and error here, but it should work.

 

[Paul Whittington]

Thanks everyone for all the good info and advice... very helpful indeed... and thanks Maik for those suggestions - it may just work if increase the F-stop and adjust the exposure time, plus the other things you suggested... will give it a try and see how it goes... thanks everyone!