Image Stablizer (IS) question

Hi all, I am new to photograher. Currently using a 500D and mounting the EF-S 10-22mm and EF-S 17-85mm IS majority of time.

Due to the nature of a person who works in office hours + having a family with frequently angry wife, majority of my shooting time is after all the family members fall asleep. (and the next morning when I go to work I will looks like shts)

I am currently doing lots of Landscapes, most pics I shots are mounted on a tripod and explosure for mroe than 10 seconds.

I have read that if you are mounting on a tripod, you should turns off the IS... then again under the same thread other's would have a completely opposite opinion, which confused me a lot.

I am assuming with the nature of my shot with long explosure time, turning on the IS on my EF-S 17-85mm IS actually make sense.

My tripod is a Tripodo GX-1227 carbon, fairly stable IMO.

Would like to see your view and experiences on this issue, many thanks in advance.

Some lenses have a tripod sensing IS mechanism. Your best bet is to turn it off. Use mirror lockup and a remote release.

The IS on a tripod can actually cause unwanted image blur as the IS motor tries to figure out how to stabailize a stable lense.

Also wearing out your battery faster.

I believe for most (all?) of the newer gen Canon IS leaving it on is no issue for faster exposure times. For longer exposures turn it off.

There have been a couple of good threads on POTN showing long exposure images with IS exhibiting blurring like a lens element was very slightly moving in a small oval (sorry, but this is the best I describe the effect). These were for lenses that were supposed to be capable of having the IS on while on a tripod. IS off for the same lens/shot was sharp.

Thanks guys. I have read those thread but then again people have different opinions. I just need some confirmation if my thinking is correct (which was wrong)

Just FYI, use mirror lockup and a self-timer or remote release for exposures around 1/30 to 2s. Mirror slap becomes an issue if you don't.

Turn it off. It's designed to help eliminate camera shake, which shouldn't be an issue on a tripod. Lock the mirror up and use a remote release and you should be fine.

+1 for turning it off when not needed, which you don't since you're on a tripod. i've always assumed that as a result of the IS, even though i have no idea how it works, that it somehow degrades/softens the image

Definitely turn it off for long exposures (= more than 0.5 second). I took some night shots with IS turned "ON" and they were misereable. Next night, same situation with IS turned "OFF": beautiful.

IS off for use on a tripod.

IS on for use off a tripod.

And as suggested use mirror lockup and remote release for best sharpness.

What is mirror lockup? Some kind of setting in 500D body?

With a DSLR what you see through the view finder is an image projected by a mirror in front of the sensor When you press the shutter button the mirror flaps up to make way for the light rays entering the lens to reach the sensor. As the mirror has some mass this movement may cause a slight tremor in the camera that can result in motion blur in the image. To avoid this tremor you can set - in the menu - the mirror to move up (after focussing) and stay in that locked position. Further information in your manual.

IS is activated when you press and hold the shutter button for a period of time, depending on the lens. Let's say 1/2 second. When you let off the shutter button for a period of time the IS de-activates. The most noticeable effect of shooting with the IS activated is that as it deactivates the lens can actually slump a bit, especially with a heavy lens. With a long exposure you will see the movement of the lens -- not good -- and you will also lose your framing.

I do have IS on, though, if I'm shooting at a long focal length, say 500-600 mm, because it helps with the little vibrations you get even on a good tripod.