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Author Topic: Turn IS off at high shutter speeds?  (Read 20079 times)

Paul Sumi

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Re: Turn IS off at high shutter speeds?
« Reply #20 on: May 03, 2011, 04:06:56 pm »

Why does Canon include IS on very long focal length lenses which, obviously, can be used only on a tripod?

For monopods or on other support for sports, journalistic and other purposes (e.g. safari photography) where tripods are not practical.
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hjulenissen

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Re: Turn IS off at high shutter speeds?
« Reply #21 on: May 03, 2011, 04:08:01 pm »

...Most of my wildlife images are taken at long distances, and any vibration reduction helps, since at 200-500 yards or more, the slightest vibration gets magnified considerably.

It may be true that at closer range, like when the subject is close to filling the frame, that turning IS off is acceptable.  As the subject gets further away, IS gets more important.
At the risk of sounding like a newbie: does the distance matter? I am expecting a given camera shake to rotate the camera by N degrees for a given focal length. Moving the subject by N degrees during exposure should result in an M pixels long blur, irrespective of distance?

-h  
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michaelnotar

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Re: Turn IS off at high shutter speeds?
« Reply #22 on: August 04, 2011, 08:29:13 pm »

when i stabilize the camera and when my subject is also not moving i find that IS hurts my image, causing bluring, even with a good shutterspeed.
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Nigel Johnson

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Re: Turn IS off at high shutter speeds?
« Reply #23 on: August 13, 2011, 04:08:54 pm »

I mainly have read details about how Canon's IS works but expect that similar issues exist with other manufacturers. Most of the information I have comes from Canon's various publications and from postings by Chuck Westfall (Technical Advisor for the Canon USA Consumer Imaging Group) on various forums and in his Tech Tips Column in the now defunct but archived 'The Digital Journalist' http://digitaljournalist.org/archives/columns.html.

My conclusions from these articles is that the effect of using IS at high speeds or on a tripod depends upon the particular version of IS fitted to the particular lens. Whilst some of the changes are related to the age of the lens (eg the simplest form is fitted to the oldest design), Canon would appear to also be selecting the type of IS based upon the expected use of the lens, eg is it wide to short-tele zoom, an extreme tele or a macro lens. The comments apply to Canon EF SLR lenses, I don't know how applicable any of this information is to Canon compact or video cameras.

As I understand it Canon have three different kinds of IS in as far as the response to tripod use is concerned:
  • those that can't detect the use of a tripod - generally these will degrade the image on a tripod as they do not respond well to the type of vibration likely to be present and the IS should be turned off, IS will probably work with a monopod;
  • those that can detect the use of a tripod and switch IS off if detected;
  • those that can detect the use of a tripod and change the response of the IS to match the likely vibration on a tripod.

I aso believe that Canon have five different approaches to dealing with panning and IS:
  • lenses with no IS mode switch - generally do not work well when panning as cannot separate out panning motion from shake;
  • lenses with an IS Mode 2 that can be used for horizontal panning, stabilisation is perpendicular to the panning direction (note I am not certain about this mode - arbitrary panning may be possible for all lenses with an IS Mode 2);
  • lenses with an IS Mode 2 that allows panning in an arbitrary direction, stabilisation is perpendicular to the panning direction;
  • lenses with an IS Mode 2 that allows panning in an arbitrary direction and an improved response to the start of panning, ie the viewfinder image does not show reverse motion (note this may only be available on lenses that also have IS Mode 3);
  • lenses with an IS Mode 3, in addition to the Mode 2, which can better ignore rapid movement between subjects.

The Canon IS generally compensates for angular shake however on the EF100mm f/2.8L Macro IS USM they introduced hybrid stabilisation that can also compensate for camera shift at macro distances.

Different lenses use a mix of these characteristics and also different generations of stabilisation offering claimed vibration reduction performance equivalent to two to four stops.

It is therefore necessary to understand what IS features a particular lens has and perhaps carry out one's own tests.

Regards
Nigel
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fotometria gr

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Re: Turn IS off at high shutter speeds?
« Reply #24 on: September 03, 2011, 06:09:03 pm »

Why does Canon include IS on very long focal length lenses which, obviously, can be used only on a tripod?
The question applies for Nikon as well! It must be that they both consider photographers as idiots, to some extend, they are are correct in doing so... Last year I bought a LN Nikkor 400mm f2.8 Afs D for 4200 Euro, I was looking for the exact version because it has identical optics as the 2(!) versions that followed, but it has a MUCH BETTER tripod leg. It also bears an aperture ring and thus I can use it with an F3 for astrophotography, the guy that sold it to me -almost unused- on that price, did so to buy the recent (at more than double the price) version that has a much worst tripod leg, doesn't have the aperture ring, but is VR! Why the hell he needed VR on a 4800kg (22 pounds) lens.....? Cheers, Theodoros www.fotometria.gr
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jonathanlung

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Re: Turn IS off at high shutter speeds?
« Reply #25 on: September 05, 2011, 12:53:46 pm »

Shooting from a moving vehicle? Or shooting from vibrating stands (e.g., bleachers).
« Last Edit: September 05, 2011, 12:57:06 pm by jonathanlung »
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fotometria gr

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Re: Turn IS off at high shutter speeds?
« Reply #26 on: September 07, 2011, 12:35:40 pm »

Shooting from a moving vehicle? Or shooting from vibrating stands (e.g., bleachers).
At 1/2000sec? We are talking really long here (400 and above) that can't be handheld remember? I am with IS up to 300/f2.8. Cheers Theodoros
« Last Edit: September 07, 2011, 12:42:13 pm by fotometria gr »
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