Volunteer needed, so we can measure rolling shutter... at DVinfo.net

Jon Fairhurst · October 1st, 2009, 11:34 AM

Let's figure out what the scan latency (rolling shutter) is on the 7D. To do that, we need somebody to shoot a quick video test with their camera and a flash unit, grab some full resolution frames, and give us the results.

Just aim the camera at something boring, like a wooden door, and manually trigger the flash a bunch of times. Then you need to capture three frames:

1) A frame in which you can see the whole flash from beginning to end.
2) A frame in which you can see the start of the flash near the bottom of the screen, immediately followed by...
3) A frame in which you see the end of the flash near the top of the screen.
Capture these frames at full resolution and let us know the frame rate (24p, 25p...) of the video.

Here's the analysis part. Do it yourself, or post the full rez frames at DVINfo and we can do it.
A) Count the number of lines of flash in capture #1. That will tell us your actual shutter duration.
B) Count the lines in captures #2 and #3 and subtract them from result A. That will tell us how many "virtual lines" there are between scans.
C) The more virtual lines there are (when the sensor is at rest), the less rolling shutter there is.

Rolling Shutter Latency = Frame time * ( sensor lines / (sensor lines + virtual lines))

I've got the 5D2, but not the 7D - otherwise, I'd do this test myself. Let's find out how fast the 7D's sensor really is!

Jon Fairhurst · October 2nd, 2009, 02:42 PM

Bump.

All you need is a 7D, a photo flash unit, and a few minutes to do the test. This will help us find out exactly how much rolling shutter the 7D has compared to the 5D2.

Chris Hurd · October 2nd, 2009, 03:08 PM

If nobody bites before tomorrow afternoon then I'll do it. I can't get to it until then though.

October 1st, 2009, 11:34 AM	#1
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	Volunteer needed, so we can measure rolling shutter... Let's figure out what the scan latency (rolling shutter) is on the 7D. To do that, we need somebody to shoot a quick video test with their camera and a flash unit, grab some full resolution frames, and give us the results. Just aim the camera at something boring, like a wooden door, and manually trigger the flash a bunch of times. Then you need to capture three frames: 1) A frame in which you can see the whole flash from beginning to end. 2) A frame in which you can see the start of the flash near the bottom of the screen, immediately followed by... 3) A frame in which you see the end of the flash near the top of the screen. Capture these frames at full resolution and let us know the frame rate (24p, 25p...) of the video. Here's the analysis part. Do it yourself, or post the full rez frames at DVINfo and we can do it. A) Count the number of lines of flash in capture #1. That will tell us your actual shutter duration. B) Count the lines in captures #2 and #3 and subtract them from result A. That will tell us how many "virtual lines" there are between scans. C) The more virtual lines there are (when the sensor is at rest), the less rolling shutter there is. Rolling Shutter Latency = Frame time * ( sensor lines / (sensor lines + virtual lines)) I've got the 5D2, but not the 7D - otherwise, I'd do this test myself. Let's find out how fast the 7D's sensor really is! __________________ Jon Fairhurst

October 2nd, 2009, 02:42 PM	#2
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	Bump. All you need is a 7D, a photo flash unit, and a few minutes to do the test. This will help us find out exactly how much rolling shutter the 7D has compared to the 5D2. __________________ Jon Fairhurst

October 2nd, 2009, 03:08 PM	#3
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	If nobody bites before tomorrow afternoon then I'll do it. I can't get to it until then though. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!