Why turn off IS

The other day I was musing on the little switch on the side of my lens and was wondering why I would ever use it.

When do the users of this forum (for good eg.) consider it necessary to switch off this ubiquitous feature?

The reasons are many, but most importantly to save battery life.

Another reason has to do with certain lens IS system failing while mounted on a tripod. IS looks for movement, and if none is found the mechanism can sometimes go into shock and start to "correct" what is not there.

Yet another is so that it doesn't wear out. It is after all a mechanical system which has to kick in whenever you pre-focus, and it is next to useless to have it on when shooting in broad daylight with shutter speeds above 250-500.

--
'Bunch of bodies, bunch of lenses, thousands of photos, endless satisfaction'

I turn IS off when I am using a shutter speed high enough not to need IS. IS takes a little time to engage and that delay might be important for shooting action such as sports, birds in flight, etc. Turning off also saves battery.

--
Gautam

Douglas Quaid said:

Another reason has to do with certain lens IS system failing while
mounted on a tripod. IS looks for movement, and if none is found the
mechanism can sometimes go into shock and start to "correct" what is
not there.

Click to expand...

You should turn off IS for long-duration tripod shots, but your reasoning is slightly off. The IS isn't going into shock or anything like that. Rather, IS is always unstable over long periods of time - the mechanisms are designed to correct movement over short periods of time, but not over long periods of time. If you're taking a 10 second exposure at night the IS mechanism is going to drift and cause blur - the mechanism is not capable of detecting this drift and correcting for it, as it is too slow. For those physics/engineering types out there - it has a very short time constant.

Most likely IS drift would add blur whether you're hand-holding or not. However, for hand-held shots the added blur is inconsequential compared to the amount of camera shake your hands will introduce. Once you have a steady platform the IS system itself generates more blur than the ground does - and so it should be turned off.

I don't think IS adds any shutter delay when it is not needed - it just won't activate unless you hold down the shutter release halfway for a second or two. It probably does drain the battery.

I usually just leave it turned on except when taking long-duration tripod shots. Compared to my old P&S, my XSi is battery paradise - so I tend not to notice the drain so much.

The only lens that I own that has IS is my 100-400. I primarily use that lens to photograph sports, usually with the lens and camera on a monopod. In these activities, the primary movement problem is the subject's not the photographer's. Furthermore, IS seems to interfere with the lens' ability to follow-focus a moving subject. From what I have read, the Sports Illustrated photographers all have long lenses with IS and very rarely use it.

--
Bob

it is so miniscule that, at the end of the day, it makes no difference.
--
I may be, and probably am, completely wrong.

Roger99 said:

The other day I was musing on the little switch on the side of my
lens and was wondering why I would ever use it.

When do the users of this forum (for good eg.) consider it necessary
to switch off this ubiquitous feature?

Click to expand...

When shooting fast moving subjects requiring camera movement for a very short duration before the shot is taken. Shooting Extreme Sports going off ramps is one example. For those I even prefocus on a spot and turn AF off, since AF won't work in those conditions (too fast). The shutter speed, for that type of shooting needs to be quite high anyway, so IS would be of no use and, more likely, hurt the image. Flying birds would be another example.

Turn IS on when you have the time to be deliberate about a shot. Otherwise, turn it off.

--
I may be, and probably am, completely wrong.

My only IS lens is the 17-55 f/2.8

I keep it turned off unless I know I will be having low shutter speeds.

--
Mark-B
http://www.msbphoto.com/

I never disable IS unless shooting on a tripod (when Canon does recommend disabling it). But then I do shoot quite a bit in low, available light (e.g., indoor with no flash) -- situations where IS is a definite plus.

--
Phil .. Canon EOS 40D, 20D, G9, SD700IS; Panasonic LX3, TZ5; Fuji F31fd.
http://www.pbase.com/phil_wheeler
http://www.flickr.com/photos/phil_ox/

Bohdan said:

it is so miniscule that, at the end of the day, it makes no difference.
--
I may be, and probably am, completely wrong.

Click to expand...

I agree regarding the issue of battery drain. I always carry two or three batteries when I'm out for a full day of shooting but I can't remember ever exhausting two fully charged batteries on the same day.

OTOH, There seems to be some validity for turning off the IS when it isn't needed and allowing the lens to focus more efficiently.

I leave mine on all the time unless I'm using a tripod. I don't agree that it really saves battery life by a noticeable amount.

To suggest one should never turn IS on is absurd.

--
mp

Yes, I have to admit that the only condition I have found that would necessitate the use of IS would be on longer lenses. Although getting a bit old and shaky now, I used to pretty much hand hold for up to around two seconds but these days lenses over 100mm (35mm equiv.) on my 450D stubbornly refuse stability. I think a large part of my problem was using IS constantly on my old PowerShot S3 and becoming complacent or lazy with technique. These are circumstances where one must be careful, I sometimes think, to allow technology to assist us but not replace basic methodology.

Roger99 said:

The other day I was musing on the little switch on the side of my
lens and was wondering why I would ever use it.

When do the users of this forum (for good eg.) consider it necessary
to switch off this ubiquitous feature?

Click to expand...

drains battery faster
can interefer with tracking sports
wears itself out for no good reason

Supertels are sharper with IS off when on a tripod than if you leave the IS on...I've verified this myself with many tests.

Depending on the lens:

1. If it is an older generation IS, it must be turned off on a tripod or it will blur the image

2. Off for a newer generation on a tripod - at shutter speeds of 1/2 second or slower where the IS drift becomes significant and can blur the image.

3. Off when I don't need it for action (high shutter speeds) since IS activation takes ~ 1 second to settle

4. If I am panning at low shutter speeds, off or mode 2, if panning the camera at higher shutter speeds, off.

Those are the rules I follow, though I generally turn it off on a tripod if I am using mirror lockup or higher shutter speeds or 1/2 second exposure or slower.

Gene

--
Gene (aka hawkman) - Walk softly and carry a big lens

Please visit my wildlife galleries at:
http://www.pbase.com/gaocus
http://hawkman.smugmug.com/gallery/1414279

Canon says turn it off on a tripod. Some lenses respond differently, and it depends on the focal length and conditions. For example, using the 500mm F4 with 1.4xII extender, you can get shake even on a tripod with cable release, just from the wind. I have observed IS steadying wind shake.

Some IS lenses do seem to induce motion when on a tripod. The 100-400 is almost spooky in this respect.

Many IS lenses--the 28-135 comes to mind--cause serious motion blur with exposures of 1-5 seconds on a tripod. Turn 'em off.

Battery life. Although Canon's manuals are silent on this, Sigma clearly states reduced battery life as a side effect of OS (their version of IS). Just listen to the IS motor and gyros on the 500mm, and you'll know the battery must be draining.

Turn it off on a tripod. Otherwise on.

--
Bill
40D circa 2007, 20D circa 2004, Rebel XT circa 2005, Nikon F circa 1967

Bob Howland said:

The only lens that I own that has IS is my 100-400. I primarily use
that lens to photograph sports, usually with the lens and camera on a
monopod. In these activities, the primary movement problem is the
subject's not the photographer's. Furthermore, IS seems to interfere
with the lens' ability to follow-focus a moving subject.

Click to expand...

In Mode1 it will indeed interfere with the panning movement, because it wants to stabilize that. But in mode2, it should work fine. (it detects the panning direction and only stablises in directions perpendicular to the panning movement).
I use mode2 a lot on my 100-400L.

BobHo said:

From what I
have read, the Sports Illustrated photographers all have long lenses
with IS and very rarely use it.

Click to expand...

In some cases you already use very short shutter times because that is needed for the subject. In that case IS isn't needed anymore, and because it needs a little time to stabilize it is then often turned off.

But in general most people with long lenses really want IS on it.

Bohdan said:

it is so miniscule that, at the end of the day, it makes no difference.

Click to expand...

It's definitely not "miniscule", but the number of shots that can be taken by one modern battery do make it effectively a non-issue under most normal circumstances. The only times battery life and use of IS have ever been an issue for me are when I've found myself without any ability to recharge for a several days or I've been shooting continually in very cold conditions.

To put some figures to it, shooting fast action sports using IS almost continually on multiple lenses from the 70-200mm f/2.8 through to the 500mm f/4, I can usually go a full day on a single battery and only rarely need to switch to my backup. By comparison, shooting closer up with non-IS lenses like the 24-70mm f/2.8, I can easily go a full week before I need to start worrying about where I've left the spare. That's quite a difference!

Andy

So really I could assume that a good development in this technology would be the capability in the setup menus to select a shutter speed at witch the IS could kick in automatically, leaving it off at speeds above and below a range deemed useful to the user.........or, another one for the wish list.