Low light, auto focus and 24P-PN vs 30P-PN. at DVinfo.net

Paul Whishaw · April 8th, 2006, 12:36 AM

I am looking for the bet settings to use with my HVX200. I've heard that the focus search is really slow in 24p mode. Is it better in 30p mode and does N in either setting help.

I'm shooting a lot of stuff in low light situations where my old PD150 would work great. The HVX however is a little dissapointing in these conditions. I didn't really want to use this camera as I am very new to it and find it a little overwhelming with all the shooting options.

I need a little advice on the best settings for low light and auto focus without having to sacrificing too much media per GB. The boss wants 24PN but he's a film nut. We're shooting mostly sports and I recommend 30P. That being said, what will be gained lost by shooting 30PN instead of just 30P.

I've spent the last few hours trying to Google this info and searching but have had little luck. Sorry if I've duplicated another thread.

Bob Grant · April 8th, 2006, 05:02 AM

I'm not a HVX 200 owner so I can only give you general advice.
Any autofocus system is going to perform better at higher frame rates, more fps, more data for it to work with.
Lower light levels also mean more gain which equals more noise which also makes it harder for the autofocus system to do its thing.
Even though the PD150 is a better camera in low light than any of the HDV cameras you'll find the same effect, only difference with the PD150 is it kicks in at a much lower light level.
I'd have to question the wisdom of shooting sports at 24fps in general, I think 30p is going to be a better choice, 60p better still. You can always discard temporal resolution, you can never get it back. Shooting at 60p gives you more options, think slomo.

Matt Irwin · April 8th, 2006, 05:25 PM

I may be wrong, but I don't think there should be an issue with this. The camera always samples a 1080/60p signal and then down-converts to whatever format you choose to record at. So, wouldn't the auto focus always work at 60 fps regardless of recorded framerate?

Barry Green · April 9th, 2006, 02:14 AM

No, because it doesn't always sample at 60p. It samples at up to 60p, depending on what frame rate you've set. So if you set it to record 12fps, it samples the ccd at 1080/12p. If you set it to record 720/48p, it samples the CCD at 1080/48p.

Back to Paul -- you're asking for things that are directly opposite. If you want good autofocus performance, the faster your frame rate the better the autofocus will perform. And the faster frame rates will take up more space on the card.

The answer to all your situations is the answer I always give for any low-light shooting circumstance: add light, if at all possible. If you want fast autofocus performance, you'll need to be able to shoot 60p or 60i for that. Autofocus performs poorly under low light circumstances anyway; autofocus needs contrast in order to work, and low light = low contrast, so autofocus always performs worse in low light circumstances. In indoor circumstances a little 20w on-camera light will make a massive improvement in the quality of video you can record.

But back to your question: there's two things you need for decent autofocus performance: enough light, and a fast refresh rate. If you have low light and a slow refresh rate, you have to accept that autofocus simply can't perform well under those conditions.

April 8th, 2006, 12:36 AM	#1
Paul Whishaw New Boot Join Date: Mar 2006 Location: Canada Posts: 21	Low light, auto focus and 24P-PN vs 30P-PN. I am looking for the bet settings to use with my HVX200. I've heard that the focus search is really slow in 24p mode. Is it better in 30p mode and does N in either setting help. I'm shooting a lot of stuff in low light situations where my old PD150 would work great. The HVX however is a little dissapointing in these conditions. I didn't really want to use this camera as I am very new to it and find it a little overwhelming with all the shooting options. I need a little advice on the best settings for low light and auto focus without having to sacrificing too much media per GB. The boss wants 24PN but he's a film nut. We're shooting mostly sports and I recommend 30P. That being said, what will be gained lost by shooting 30PN instead of just 30P. I've spent the last few hours trying to Google this info and searching but have had little luck. Sorry if I've duplicated another thread.

April 8th, 2006, 05:25 PM	#3
Matt Irwin Major Player Join Date: Jul 2004 Location: Los Angeles, CA Posts: 327	I may be wrong, but I don't think there should be an issue with this. The camera always samples a 1080/60p signal and then down-converts to whatever format you choose to record at. So, wouldn't the auto focus always work at 60 fps regardless of recorded framerate? __________________ Matt Irwin DP / matt.irwincine.com

April 8th, 2006, 05:02 AM	#2
Bob Grant Trustee Join Date: Nov 2005 Location: Sydney Australia Posts: 1,570	I'm not a HVX 200 owner so I can only give you general advice. Any autofocus system is going to perform better at higher frame rates, more fps, more data for it to work with. Lower light levels also mean more gain which equals more noise which also makes it harder for the autofocus system to do its thing. Even though the PD150 is a better camera in low light than any of the HDV cameras you'll find the same effect, only difference with the PD150 is it kicks in at a much lower light level. I'd have to question the wisdom of shooting sports at 24fps in general, I think 30p is going to be a better choice, 60p better still. You can always discard temporal resolution, you can never get it back. Shooting at 60p gives you more options, think slomo.

April 9th, 2006, 02:14 AM	#4
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	No, because it doesn't always sample at 60p. It samples at up to 60p, depending on what frame rate you've set. So if you set it to record 12fps, it samples the ccd at 1080/12p. If you set it to record 720/48p, it samples the CCD at 1080/48p. Back to Paul -- you're asking for things that are directly opposite. If you want good autofocus performance, the faster your frame rate the better the autofocus will perform. And the faster frame rates will take up more space on the card. The answer to all your situations is the answer I always give for any low-light shooting circumstance: add light, if at all possible. If you want fast autofocus performance, you'll need to be able to shoot 60p or 60i for that. Autofocus performs poorly under low light circumstances anyway; autofocus needs contrast in order to work, and low light = low contrast, so autofocus always performs worse in low light circumstances. In indoor circumstances a little 20w on-camera light will make a massive improvement in the quality of video you can record. But back to your question: there's two things you need for decent autofocus performance: enough light, and a fast refresh rate. If you have low light and a slow refresh rate, you have to accept that autofocus simply can't perform well under those conditions.