View Full Version : Image stabilizer


Ray Danders
December 14th, 2002, 06:21 PM
In my GL2 manual it recommended to turn off the image stabilizer when using a tripod. That raises a question. Is the film somehow better with this option off when used in an already stable situation?

Frank Granovski
December 14th, 2002, 06:29 PM
Optical stabilizers can degrade the video, about 10%, depending on the cam and its OIS. It's still a whole lot better than DIS. Pro cams don't even come with a stabilzer: you use either your shoulder, tripod or other stabilization device.

Jeff Donald
December 14th, 2002, 06:40 PM
Canon has a full range of OIS lenses for ENG/EFP and HDTV. Many of the super steady sport shots (golf, baseball) are Canon lenses. Canon has OIS available http://www.usa.canon.com/html/industrial_bctv/ for all types of video productions.

Jeff

Chris Hurd
December 14th, 2002, 07:31 PM
When the camera is mounted on a tripod, there's no stray motion for the OIS to fight. The only motion is your intended pan, tilt or zoom. OIS tries to compensate for this motion, resulting in jerky pans, jerky tilts etc. To prevent this, you always want to turn OIS off when the camera is on a tripod. Hope this helps,

Ray Danders
December 15th, 2002, 04:15 PM
Thanks Gentlemen, I knew there had to be some logical reason. Appreciate your help.

Joshua Wachs
December 21st, 2002, 07:24 PM
I've been meaning to ask that question for weeks. Thanks for asking and great answers.

Tom Voigt
December 22nd, 2002, 08:45 PM
I have been getting noticeable vibration in the image when recording musical theater events with loud sharp musical transients. It happened just today when I was set up 20 feet from a Taiko drum.

My setup is a low end Bogen-Manfrotto tripod and a Canon Optura Pi - with image stabilization turned on.

Does optical image stabilization have any effect on this sort of high frequency (100hz?) vibration? Would turning off image stabilization have any effect in this case? Would electronic image stabilization work better here?

Oh yes, and another place where you get stray motion even when mounted on a tripod is when the tripod gets kicked or otherwise hit.

Don Palomaki
December 23rd, 2002, 03:39 AM
Whethr ot not OIS woudl help the drum=caused vibration would depend on how it is coupled to the system. It would help it the image effect is caused by movement of the whole camera, but probablynot if it is caused by movementof the VAP only in response to the drum beat.

EIS might work better in this case, one of the few cases where EIS can be more effective, but you will pay the EIS image quality penalty.

The main issue with IS is the tendency to lag and over shoot on pans and tilts because the sensors cannot tell the diffeence between a shake and the start/end of a pan/tilt or other intended camera movement.

Andre De Clercq
December 23rd, 2002, 07:40 AM
Image stabilisation systems (EIS,OIS) don't stabilize shake frequency components higher than 20 Hz. So audio induced shakes are not stabilized.

Tom Voigt
December 23rd, 2002, 06:30 PM
My zooms and pans are quite slow, so I don't think that the image stabilization has any effect on that.

For the audio induced shakes, maybe a sand bag draped over the camera? And a bigger heavier tripod would also help.

Thanks for the great info!

Don Palomaki
December 24th, 2002, 04:29 AM
OIS should not effect a zoon, but at the start of a pan you may detect a slight bit of lag and and at the end a wee bit of overshoot or drift. This is most noticeable when shooting froma sturdy base such as a good tripod. It is not as apparent inhandheld because most handheld shots are not as stable.

Jeff Donald
December 24th, 2002, 06:17 AM
Canon has a switch on their longer 35mm lenses that can disable the OIS in the horizontal direction. It is very effective and would be a nice inclusion on their prosumer video cameras.

I would suspect the low frequency of the drum beats is being transmitted through the aluminum legs and is actually vibrating the VAP itself. Sort of inducing it's own motion and unsharpness.

A wooden tripod would help a lot under those conditions. Metal tripods are very prone to that type of vibration.

Jeff

Andre De Clercq
December 24th, 2002, 09:38 AM
Depending on the sound wavefront direction and the shooting direction, light itself can become dynamically bended due to the dynamic changes of air pressure. Only changing the relative angles can solve this problem. A static example of this air pressure dependent bending is known as "mirages" (fata morgana)