1/30th And Slower, And Resolution at DVinfo.net

Dave Largent · January 4th, 2004, 08:39 PM

Do you really lose 50%? Or what are the facts?
Anyone know why this is?

Rob Lohman · January 5th, 2004, 05:24 AM

It seems to be like that, indeed. Don't know if it is that much
though. Found some more information on this thread

Tom Hardwick · January 5th, 2004, 08:06 AM

Yes, you do lose half of your vertical resolution (horizontal resolution stays the same of course) because at shutter speeds slower than 1/60 (NTSC) the picture is composed of one field only.

It's easy enough to test out. Just set up your camera on a tripod and take two stills to memorystick - one at 1/60th, the other at 1/30th. Pull these frames into Photoshop and notice the stair-stepping on diagonal lines at 1/30th - the reason being the lack of the other field.

tom.

Dave Largent · January 5th, 2004, 10:58 AM

Tom,
My understanding was it's still two fields under 1/60th.
Are you saying it's not interlaced below 1/60th?
I thought the interlacing is what *causes* the stair stepping.

Tom Hardwick · January 5th, 2004, 11:04 AM

Yes, it's still two fields. Problem is it's the same field.

January 4th, 2004, 08:39 PM	#1
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	1/30th And Slower, And Resolution Do you really lose 50%? Or what are the facts? Anyone know why this is?

January 5th, 2004, 05:24 AM	#2
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	It seems to be like that, indeed. Don't know if it is that much though. Found some more information on this thread __________________ 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

January 5th, 2004, 08:06 AM	#3
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Yes, you do lose half of your vertical resolution (horizontal resolution stays the same of course) because at shutter speeds slower than 1/60 (NTSC) the picture is composed of one field only. It's easy enough to test out. Just set up your camera on a tripod and take two stills to memorystick - one at 1/60th, the other at 1/30th. Pull these frames into Photoshop and notice the stair-stepping on diagonal lines at 1/30th - the reason being the lack of the other field. tom.

January 5th, 2004, 10:58 AM	#4
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	Tom, My understanding was it's still two fields under 1/60th. Are you saying it's not interlaced below 1/60th? I thought the interlacing is what causes the stair stepping.

January 5th, 2004, 11:04 AM	#5
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Yes, it's still two fields. Problem is it's the same field.