Canon IS lenses and exposure

[jrm]

In many places, people talk about the IS feature as the "equivalent of two extra stops." I thought that meant that you could basically shoot at a slower shutter speed than you normally could, because the IS would compensate for camera shake.

However, the way some people discuss it, they almost imply that at the same settings, more light enters the lens. One place I saw someone write that the "xxx 2.8 IS is the same as the xxx 1.8 non-IS in actual performance."

I know this sounds like a dumb question, but the way some people are talking that has me confused. An exposure of, for example, 1/100 sec f/2.8 is the same on any lens, IS or non-IS - right? What is meant is that IS allows you to shoot at slower shutter speeds allowing you to take shots that would be "too dark" for non-IS lenses... or am I missing something here?

[defordphoto]

Your first interpretation was correct. IS means Image Stabilization. There are some of the higher end L-series lenses that actually have two modes of IS, one for normal shooting and the other to assist with stabilizing the lens during horizontal panning.

[MarkH]

The 70-200 2.8L IS is a newer lens and the IS gives 3 stops of stabalization. But this does NOT give faster shutter speeds (Yes your first interpretation was bang on). For fast shutter speeds you need a wide aperture, for being able to hand hold at slower speeds you need IS. The longer the zoom the more you need either IS or a tripod.

[jrm]

Thanks, that's what I thought. Again, what was bothering me is the way some people were discussing the IS. In particular, one person was comparing the 2.8IS with a 1.8 non-IS and saying that they were both equal because of the "extra 2 stops IS gives you." Shutter speed never entered into the conversation and the only reference was to lens speed.

It almost made it sound that at the same shutter speed, the 2.8 with IS would magically give you the same exposure as the 1.8 without IS. I knew this had to be wrong, and just wanted to make sure I understood it correctly.

(Especially since my 70-200/2.8IS is on the way)

[defordphoto]

The 70-200 2.8L IS is a newer lens and the IS gives 3 stops of stabalization.

Three? hhmmmmm...Maybe if you're very steady. 1.5-2 you can bank on. 3 is pushing it. Either way it does help, but no JRM, it won't magically pull more light into the lens.

Another option people use too is to underexpose by 1.5-2 stops, shoot in RAW and recover the underexposure in post-processing.

[MarkH]

The 70-200 2.8L IS is a newer lens and the IS gives 3 stops of stabalization.

Three? hhmmmmm...Maybe if you're very steady. 1.5-2 you can bank on. 3 is pushing it.

That's what Canon claim.

I'm pretty sure I can use my 28-135 IS hand held 2 stops slower with IS on and that is what canon claim. Canon also claim 2 stops for the 100-400 IS.

You have both the 70-200 IS and the 100-400 IS so why don't you try some tests at 200mm and let us know if the IS is really a stop better on your 70-200 then on your 100-400. It would be nice to know how accurate Canon's claims are.

[defordphoto]

Really? I was not aware they claimed three. Is that in the manual? Or do you have a link to that claim? The IS would provide more stability on the 70-200 over the 100-400 inherently just because of the shorter focal length, just as my 28-135IS (should) provide even more stability because of its shorter focal length.

[Belmondo]

Rumor...
Canon is going to include IS on any lens with a street price in excess of $1,000.00 becasue after spending money like that, most people's hands will shake.

[defordphoto]

LOL! Actually what people are saying is that they need to put the IS in the camera, not the lens. Some people refuce to buy IS lenses as they are positive that it will eventually end up in the camera. The very wll may be, but they just make soooo much money off of lens IS I can't imagine them doing that anytime soon.

[MarkH]

Really? I was not aware they claimed three. Is that in the manual? Or do you have a link to that claim? The IS would provide more stability on the 70-200 over the 100-400 inherently just because of the shorter focal length, just as my 28-135IS (should) provide even more stability because of its shorter focal length.

http://www.usa.canon.com/eflenses/lineup/telephotozoom/index.html

Click on the pic of the lens and the description pops up.

Incorporating Canon’s second generation Image Stabilization technology, this telephoto zoom responds in as little at 0.5 seconds, while providing up to three stops of correction for camera shake.

The stability of the different lenses should be comparable even at different focal lengths, if I can hand hold my 28-135 IS at 1/60 sec without IS and 1/15 sec with IS while at max zoom then I have gained 2 stops. If you can hand hold your 100-400 L IS at 1/200 sec without IS and 1/50 sec with IS then you have gained 2 stops.

[Nolz]

Rumor...
Canon is going to include IS on any lens with a street price in excess of $1,000.00 becasue after spending money like that, most people's hands will shake.
thanks for the laugh :lol: im only thnking about L glass and my hands are already very weak!

[defordphoto]

Thanks for the followup there Mark. Three stops eh? Well I guess in perfect conditions that might be true but in reality that'd be pushing it. Either way, IS is an awesome feature when you need it.