How to Continuous Focus on A7 During Video
Autofocus on Sony a7iii going in and out of focus constantly during video
Hi
My husband and I both teach at a university and because of the recent lockdown are uploading part of our teaching as video-lectures.
I use a Sony a7iii for photography and thought since we have to do this, and it's a straight forward set up without motion, we might as well use the nice camera for the video lectures. I know the photography settings fairly well and haven't had problems with that. Yet I'm not very experienced with video, so this is most likely user error.
During the entire test run we did (roughly 15minutes), the camera constantly kept going in and out of focus in very small intervals of ~2 seconds, even though the camera was just on a stand and the subject was simply sitting at the table talking.
The lens used was a Samyang 35mm, 2.8 FE, so that might also affect the auto focus working properly (although, this is my preferred travel lens due to its size and I've hardly ever had issues).
The focus settings were AF-C, AF with face preference. But the AF drive speed was set to fast and AF track sensitivity to sensitive. The latter two might affect the focussing? The aperture was at 5.6, which might be contributing, since the subject was roughly 5-6 feet away.
Also, the subject was close to the background and the picture profile and lighting used might have lessened the contrast. Can that be the problem? Has anyone had a similar problem and knows a solution?
edit: focus setting was on wide.
LenRivers • Senior Member • Posts: 3,827
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
rumpelstilzchenCat wrote:
Hi
My husband and I both teach at a university and because of the recent lockdown are uploading part of our teaching as video-lectures.
I use a Sony a7iii for photography and thought since we have to do this, and it's a straight forward set up without motion, we might as well use the nice camera for the video lectures. I know the photography settings fairly well and haven't had problems with that. Yet I'm not very experienced with video, so this is most likely user error.
During the entire test run we did (roughly 15minutes), the camera constantly kept going in and out of focus in very small intervals of ~2 seconds, even though the camera was just on a stand and the subject was simply sitting at the table talking.
The lens used was a Samyang 35mm, 2.8 FE, so that might also affect the auto focus working properly (although, this is my preferred travel lens due to its size and I've hardly ever had issues).
The focus settings were AF-C, AF with face preference. But the AF drive speed was set to fast and AF track sensitivity to sensitive. The latter two might affect the focussing? The aperture was at 5.6, which might be contributing, since the subject was roughly 5-6 feet away.
Also, the subject was close to the background and the picture profile and lighting used might have lessened the contrast. Can that be the problem? Has anyone had a similar problem and knows a solution?
edit: focus setting was on wide.
If you are stationary not moving try AF-S, be sure the camera is not in Pre-AF so it is Off.
AF tracking should be fine,
I would put the camera in manual exposure and manually set shutter speed to double the frames per second. So if you are using 30 FPS shutter speed is 1/60 th as a constant. I would also stop down to F 5.6 or or 8 and use ISO 400 see what you get. You also need good light.
Lock it down on a tripod
Past that use a iPad or look at an inexpensive camcorder they do not cost alot.
The other aspect is audio so an external mic would be a good thing to have as well.
Check out the Rocky Nook.com site for a E-book on the camera. The website DSLR video shooter may also be helpful
MILC man • Senior Member • Posts: 5,408
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
rumpelstilzchenCat wrote:
Hi
My husband and I both teach at a university and because of the recent lockdown are uploading part of our teaching as video-lectures.
I use a Sony a7iii for photography and thought since we have to do this, and it's a straight forward set up without motion, we might as well use the nice camera for the video lectures. I know the photography settings fairly well and haven't had problems with that. Yet I'm not very experienced with video, so this is most likely user error.
During the entire test run we did (roughly 15minutes), the camera constantly kept going in and out of focus in very small intervals of ~2 seconds, even though the camera was just on a stand and the subject was simply sitting at the table talking.
with stationary targets like that, you should have continuous af turned off, that's how the pros do it.
set the camera up so that you can blip the af to focus it, right before you start recording, then leave it alone.
you can see how that works in, say, a 60 minutes interview piece, if the subject suddenly leans forward, and then back to where he was, you'll see him go out of focus and then back in, as he sits back up in the plane of focus... the camera operator generally does not try to track every movement.
when you get serious about video, you'll find yourself automatically de-constructing scenes like that, asking yourself how the lighting/audio/focus was set up.
here is a helpful video for setting up sony for video use, I cued it to start at the auto/manual af mode button setup:
https://youtu.be/Wa5voIxwsPI?t=3m25s
there are other ways of doing that as well... here is an older video from 2017, that talks about setting up a custom button to turn the af off: https://youtu.be/3UxZJpR7zQA?t=6m40s
voronspb • Senior Member • Posts: 1,998
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
Unfortunately, a lot of third-party lenses have certain issues with video AF. Even though they may work perfectly fine for stills.
-- hide signature --
Vladimir Gorbunov
Sony a6500 Sony a7 III Tamron 17-28mm F2.8 Di III RXD Sony FE 35mm F1.8 Tamron 70-180mm F2.8 Di III VXD +8 more
Magnar W • Veteran Member • Posts: 6,702
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
rumpelstilzchenCat wrote:
During the entire test run we did (roughly 15minutes), the camera constantly kept going in and out of focus in very small intervals of ~2 seconds, even though the camera was just on a stand and the subject was simply sitting at the table talking.
Why not simply turn off autofocus?
Manual focus is great for a lot of video work, especially for static and predictable slow subject motion.
Sony a7 Sony a7R III Sony a7 IV Sony FE 24-70mm F4 OSS Sony FE 90mm F2.8 macro +4 more
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
Thank you, everybody!
I'll try manual focus or AF-S.
Shutter speed was already correctly set to 1/50 for 24p and light was actually good. Just that pulsating autofocus...
Thanks!
voronspb • Senior Member • Posts: 1,998
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
Is there really AF-S mode for video? I don't think so. Besides, AF-S pulsates a bit by design while focusing, because it utilizes CDAF at the end.
-- hide signature --
Vladimir Gorbunov
Sony a6500 Sony a7 III Tamron 17-28mm F2.8 Di III RXD Sony FE 35mm F1.8 Tamron 70-180mm F2.8 Di III VXD +8 more
SQLGuy • Forum Pro • Posts: 12,161
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
voronspb wrote:
Is there really AF-S mode for video? I don't think so. Besides, AF-S pulsates a bit by design while focusing, because it utilizes CDAF at the end.
On the A7R2, at least, no, there is not. Just AF-C and MF.
However, the AF-S pulsing is only once, not on some continuous cycle as is reported here.
I just tried the same lens, though, and, at least for a static scene, I do not see it cycling or pulsing in AF-C video. I recently installed the latest (version 5) firmware on it. The version 5 firmware includes AF-C improvements...
-- hide signature --
A7R2 with SEL2470Z and a number of adapted lenses (Canon FD, Minolta AF, Canon EF, Leica, Nikon...); A7R converted to IR.
Canon PowerShot G9 Canon PowerShot S100 (2000) Sony Mavica FD-91 Sony RX100 VI Canon EOS-1D +41 more
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
voronspb wrote:
Is there really AF-S mode for video? I don't think so. Besides, AF-S pulsates a bit by design while focusing, because it utilizes CDAF at the end.
Yes, I just realized that too. There's only MF and AF-C
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
SQLGuy wrote:
I just tried the same lens, though, and, at least for a static scene, I do not see it cycling or pulsing in AF-C video. I recently installed the latest (version 5) firmware on it. The version 5 firmware includes AF-C improvements...
Good point, I'll try and update it.
For now, MF + narrower aperture work just fine if we're not too animated while lecturing
voronspb • Senior Member • Posts: 1,998
Re: Autofocus on Sony a7iii going in and out of focus constantly during video
SQLGuy wrote:
I just tried the same lens, though, and, at least for a static scene, I do not see it cycling or pulsing in AF-C video. I recently installed the latest (version 5) firmware on it. The version 5 firmware includes AF-C improvements...
Samyang is making big improvements in their FW updates. In early versions you had to set the FL in IBIS settings manually (such recommendation exists in Manual), and in recent versions this limitation was lifted AFAIK.
-- hide signature --
Vladimir Gorbunov
Sony a6500 Sony a7 III Tamron 17-28mm F2.8 Di III RXD Sony FE 35mm F1.8 Tamron 70-180mm F2.8 Di III VXD +8 more
shelleyawneyed1946.blogspot.com
Source: https://www.dpreview.com/forums/thread/4475410
0 Response to "How to Continuous Focus on A7 During Video"
Postar um comentário