Wobbly snow

John Papadopoulos · December 12th, 2007, 11:16 PM

The snow is practically constant so it shouldn't be thermal or autofocus related. Autofocus does not seam to hunt, it actually has tons of depth of field.

I think it's a combination of OIS, rolling shutter and high frame rate. OIS is IMHO not fast enough and some of the frames catch OIS in motion which makes the rolling shutter problem appear. Same as shaking the camera vertically without OIS. Just a theory:)

Dave Elston · December 13th, 2007, 04:47 AM

If we're having a straw poll on this, my vote is that its a thermal effect - you can see rails that must lead to a door, where quite probably one would expect to find an overhead heater bellowing a heat curtain (as found in many public buildings in cold lattitudes).

Colin, you mention you were outside, perhaps the door nearby was opened during the shot? Can you recall any nearby heat sources other than yourself - or maybe you removed gloves exposing toasty hands ...? ;0)

It's definitely something that deserves some more testing!

Steven Thomas · December 13th, 2007, 08:16 AM

It's isolated and looks thermal to me.

Dave Elston · December 13th, 2007, 09:18 AM

A good way to test the rolling shutter theory would be to setup a CCD camera alongside shooting at 60fps (eg, an HD250) to see if the same effect is present.

Colin, do you have access to any other CCD cameras on campus that you could do a quick comparison with?

Steven Thomas · December 13th, 2007, 09:30 AM

I'm not following anyone who thinks this is a rolling shutter artifact, please explain.

I've shot rain, moving water, why would snow be any different.

This isn't the first time I've (and many) have seen this type of thermal wave distortion.

Ethan Cooper · December 13th, 2007, 10:01 AM

Quote:

Originally Posted by Steven Thomas

It's isolated and looks thermal to me.

Isolated being the key word here. It can't be rolling shutter because of this very fact.
It sure as hell looks like a thermal to me.

December 13th, 2007, 04:47 AM	#17
Dave Elston Regular Crew Join Date: Oct 2004 Location: UK 50i/25p Land Posts: 103	If we're having a straw poll on this, my vote is that its a thermal effect - you can see rails that must lead to a door, where quite probably one would expect to find an overhead heater bellowing a heat curtain (as found in many public buildings in cold lattitudes). Colin, you mention you were outside, perhaps the door nearby was opened during the shot? Can you recall any nearby heat sources other than yourself - or maybe you removed gloves exposing toasty hands ...? ;0) It's definitely something that deserves some more testing! __________________ Play to Learn, Learn to Earn, Earn to Play... Dave - Broader Pictures

December 13th, 2007, 09:18 AM	#19
Dave Elston Regular Crew Join Date: Oct 2004 Location: UK 50i/25p Land Posts: 103	A good way to test the rolling shutter theory would be to setup a CCD camera alongside shooting at 60fps (eg, an HD250) to see if the same effect is present. Colin, do you have access to any other CCD cameras on campus that you could do a quick comparison with? __________________ Play to Learn, Learn to Earn, Earn to Play... Dave - Broader Pictures

December 12th, 2007, 11:16 PM	#16
John Papadopoulos Major Player Join Date: Nov 2007 Location: Athens Greece Posts: 336	The snow is practically constant so it shouldn't be thermal or autofocus related. Autofocus does not seam to hunt, it actually has tons of depth of field. I think it's a combination of OIS, rolling shutter and high frame rate. OIS is IMHO not fast enough and some of the frames catch OIS in motion which makes the rolling shutter problem appear. Same as shaking the camera vertically without OIS. Just a theory:)

December 13th, 2007, 08:16 AM	#18
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	It's isolated and looks thermal to me.

December 13th, 2007, 09:30 AM	#20
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	I'm not following anyone who thinks this is a rolling shutter artifact, please explain. I've shot rain, moving water, why would snow be any different. This isn't the first time I've (and many) have seen this type of thermal wave distortion.