2 Technical Questions at DVinfo.net

Phil French · June 2nd, 2002, 09:44 PM

I have two questions:

1) Are there any problems with using "frame movie mode" when shooting for broadcast and can it cause problems with MPEG2 compression?

2) Can someone remind me why it is better to turn off "image stabilization" when shooting from a tripod? I know I've read this before (probably on this forum), but I can't recall.

Thanks!

Ken Tanaka · June 2nd, 2002, 10:41 PM

I can't answer #1 but am sure that someone here can.

Regarding #2, the reason that it may be a good idea to turn image stabilization (IS) off for mounted shots it to prevent the IS system from attempting to briefly attempt to compensate for controlled pans and tilts. If IS is on during, say, a pan you can experience a funky kind of lag particularly at the start of the pan if the IS system is activated. Try it for yourself.

Rob Lohman · June 3rd, 2002, 03:31 AM

I can partially answer question 1. I think the broadcast world
likes to have interlaced, because they air interlaced. But the best
source to ask is the broadcast world itself. Regarding MPEG2,
it does not matter. MPEG2 suites interlaced as well as progressive.
It might be that progressive is a little bit better to encode
(less diferences), but other than that, it will encode both fine
as long as you tell your mpeg encoder that it is interlaced
(and which field is first) or that it is progressive. That is all.

A DVD player for example will make the signal interlaced again
(unless you have a progressive output on your DVD player and
have connected something to this port that understands
progressive, ie expensive TV's or projectors).

Phil French · June 3rd, 2002, 04:59 PM

Thanks, Ken and Rob, for your answers. Your help is much appreciated!

June 5th, 2002, 09:45 AM

For Question #2:

Referring to what Ken Tanaka mentioned, I've heard that effect being called a "Stuttered Pan" Which is actually a good name for it.

Recently I had to shoot a play from the back of the theatre and was requested to include a lot of closeups of the performers. To push in that far from a distance always introduces camera shake, even on a tripod.

After some practice I kind of learned the "mindset" of how the IS decides to pan and tilt in order to compensate for operator shake. You can, with practice, start a pan in such a way that you know how far you have to pan before the IS takes over and moves everything over an additional 1/4 screen. At this point you can continute panning at the same speed the IS pans. This counteracts the IS effect and you get a smooth pan. You also get to learn when to begin stopping the pan so the IS will not move the frame when the camera stops moving.

I know this all sounds complicated and I only figured it out by paying close attention to the IS's logic, and practicing!

Normally I keep the IS off when using a tripod, but some shoots require the trade-off removing camera shake at the expense of a little bit of composition error.

I know there are a lot of readers cringing at this idea, but how to you remove camera shake when you are pushed in about 80% of the lens and the subject is very stationary. The minute camera shake drives me crazy when I watch it back. Of course I could spend $5,000 for a better tripod, but my budget doesn't allow for that.

Good luck!

June 3rd, 2002, 03:31 AM	#3
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	I can partially answer question 1. I think the broadcast world likes to have interlaced, because they air interlaced. But the best source to ask is the broadcast world itself. Regarding MPEG2, it does not matter. MPEG2 suites interlaced as well as progressive. It might be that progressive is a little bit better to encode (less diferences), but other than that, it will encode both fine as long as you tell your mpeg encoder that it is interlaced (and which field is first) or that it is progressive. That is all. A DVD player for example will make the signal interlaced again (unless you have a progressive output on your DVD player and have connected something to this port that understands progressive, ie expensive TV's or projectors). __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

June 3rd, 2002, 04:59 PM	#4
Phil French Regular Crew Join Date: Feb 2002 Location: Lousana, Alberta, Canada Posts: 146	Thanks, Ken and Rob, for your answers. Your help is much appreciated! __________________ Nature Boy

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June 2nd, 2002, 09:44 PM	#1
Phil French Regular Crew Join Date: Feb 2002 Location: Lousana, Alberta, Canada Posts: 146	2 Technical Questions I have two questions: 1) Are there any problems with using "frame movie mode" when shooting for broadcast and can it cause problems with MPEG2 compression? 2) Can someone remind me why it is better to turn off "image stabilization" when shooting from a tripod? I know I've read this before (probably on this forum), but I can't recall. Thanks! __________________ Nature Boy

June 2nd, 2002, 10:41 PM	#2
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	I can't answer #1 but am sure that someone here can. Regarding #2, the reason that it may be a good idea to turn image stabilization (IS) off for mounted shots it to prevent the IS system from attempting to briefly attempt to compensate for controlled pans and tilts. If IS is on during, say, a pan you can experience a funky kind of lag particularly at the start of the pan if the IS system is activated. Try it for yourself. __________________ Lady X Films: A lady with a boring wardrobe...and a global mission. Hey, you don't have enough stuff! Buy with confidence from our sponsors. Hand-picked as the best in the business...Really! See some of my work one frame at a time: www.KenTanaka.com

June 5th, 2002, 09:45 AM	#5
randor10 Posts: n/a	For Question #2: Referring to what Ken Tanaka mentioned, I've heard that effect being called a "Stuttered Pan" Which is actually a good name for it. Recently I had to shoot a play from the back of the theatre and was requested to include a lot of closeups of the performers. To push in that far from a distance always introduces camera shake, even on a tripod. After some practice I kind of learned the "mindset" of how the IS decides to pan and tilt in order to compensate for operator shake. You can, with practice, start a pan in such a way that you know how far you have to pan before the IS takes over and moves everything over an additional 1/4 screen. At this point you can continute panning at the same speed the IS pans. This counteracts the IS effect and you get a smooth pan. You also get to learn when to begin stopping the pan so the IS will not move the frame when the camera stops moving. I know this all sounds complicated and I only figured it out by paying close attention to the IS's logic, and practicing! Normally I keep the IS off when using a tripod, but some shoots require the trade-off removing camera shake at the expense of a little bit of composition error. I know there are a lot of readers cringing at this idea, but how to you remove camera shake when you are pushed in about 80% of the lens and the subject is very stationary. The minute camera shake drives me crazy when I watch it back. Of course I could spend $5,000 for a better tripod, but my budget doesn't allow for that. Good luck!