FX7 1/30th shutter with 60i output--what is happening? at DVinfo.net

Robert Altman · July 3rd, 2007, 06:51 AM

In dim light setting the shutter speed to 1/30 brightens up the image--but how is this possible in 60i video? What is the slow shutter speed doing--creating a 30p look? Is it averaging two 60i frames? Has anyone looked at the video shot with this shutter speed to analyze it?

I always run my 60i video through deinterlacing filters in FCP to convert to 30p before output (otherwise it looks ugly on progressive screen monitors). Can I shoot with 1/30th shutter speed and avoid this step? Will I have too much motion blur?

Anyone with any knowledge/experience in these settings?

--Robert

Joe Busch · July 3rd, 2007, 07:25 AM

I'm guessing it just doubles the fields/frames

Douglas Spotted Eagle · July 3rd, 2007, 08:01 AM

The resolution at 3/6 seconds is 512x240. Fields are doubled at 12 seconds. Not much information there. It's barely useful for standard resolution, and not useable at all for HD resolutions. Works great for the web, however.

Seth Bloombaum · July 3rd, 2007, 08:58 AM

Using 1/30 second shutter speed has nothing to do with 60i vs. 30p. It just keeps the shutter open longer, allowing more light on the chip. This is cumulative, so, yes, you get double the light when doubling the time the chip receives light.

OK, I've used it for talking head interviews in low light. If the subject is moving their arms & hands a lot, it will be noticeable to those who know what they're looking at.

There will be more motion blur. It no longer looks like TV, but, you may like the look. I've not done a 30p conversion from video shot 1/30 60i.

Slower shutter speeds would have to be classified as a visual effect in scenes that contain significant motion.

Marcus Marchesseault · July 3rd, 2007, 12:57 PM

I did some recording at 30P and it does not look at all like 512x240. Spot, are you sure you aren't talking about the "Smooth" record for high fps footage?

From what I can tell, the 30P is stored like 60i but the fields don't have any difference in time so there are none of the "comb" edges between fields with motion.

Douglas Spotted Eagle · July 3rd, 2007, 01:17 PM

Argghh...I was looking at a post on Super Smooth Slo Mo in another thread, and put the response in this one. Sorry for any confusion. Duh! Thanks for the catch.

July 3rd, 2007, 06:51 AM	#1
Robert Altman Regular Crew Join Date: Jun 2007 Location: New York Posts: 28	FX7 1/30th shutter with 60i output--what is happening? In dim light setting the shutter speed to 1/30 brightens up the image--but how is this possible in 60i video? What is the slow shutter speed doing--creating a 30p look? Is it averaging two 60i frames? Has anyone looked at the video shot with this shutter speed to analyze it? I always run my 60i video through deinterlacing filters in FCP to convert to 30p before output (otherwise it looks ugly on progressive screen monitors). Can I shoot with 1/30th shutter speed and avoid this step? Will I have too much motion blur? Anyone with any knowledge/experience in these settings? --Robert

July 3rd, 2007, 08:01 AM	#3
Douglas Spotted Eagle VASST Join Date: Jan 2004 Location: Stockton, UT Posts: 5,648	The resolution at 3/6 seconds is 512x240. Fields are doubled at 12 seconds. Not much information there. It's barely useful for standard resolution, and not useable at all for HD resolutions. Works great for the web, however. __________________ Douglas Spotted Eagle/Spot Author, producer, composer Certified Sony Vegas Trainer http://www.vasst.com

July 3rd, 2007, 01:17 PM	#6
Douglas Spotted Eagle VASST Join Date: Jan 2004 Location: Stockton, UT Posts: 5,648	Argghh...I was looking at a post on Super Smooth Slo Mo in another thread, and put the response in this one. Sorry for any confusion. Duh! Thanks for the catch. __________________ Douglas Spotted Eagle/Spot Author, producer, composer Certified Sony Vegas Trainer http://www.vasst.com

July 3rd, 2007, 07:25 AM	#2
Joe Busch Major Player Join Date: Feb 2007 Location: Sammamish, WA Posts: 398	I'm guessing it just doubles the fields/frames

July 3rd, 2007, 08:58 AM	#4
Seth Bloombaum Inner Circle Join Date: Sep 2003 Location: Portland, Oregon Posts: 3,420	Using 1/30 second shutter speed has nothing to do with 60i vs. 30p. It just keeps the shutter open longer, allowing more light on the chip. This is cumulative, so, yes, you get double the light when doubling the time the chip receives light. OK, I've used it for talking head interviews in low light. If the subject is moving their arms & hands a lot, it will be noticeable to those who know what they're looking at. There will be more motion blur. It no longer looks like TV, but, you may like the look. I've not done a 30p conversion from video shot 1/30 60i. Slower shutter speeds would have to be classified as a visual effect in scenes that contain significant motion.

July 3rd, 2007, 12:57 PM	#5
Marcus Marchesseault Trustee Join Date: Nov 2005 Location: Honolulu, HI Posts: 1,961	I did some recording at 30P and it does not look at all like 512x240. Spot, are you sure you aren't talking about the "Smooth" record for high fps footage? From what I can tell, the 30P is stored like 60i but the fields don't have any difference in time so there are none of the "comb" edges between fields with motion.