talk to me about IS

nyamy · Jul 23, 2008

I'm looking for another lens for my canon xsi
the kit lens has IS
as features go, how important is this?
I mostly want to get good close ups of my kids. most of the pics I'm taking these days are outdoors.

prodigy2k7 · Jul 23, 2008

The IS is mostly for low light still photography.
In low light you tend to have slower shutter speeds lets say 1/50 for instance...

With a slow shutter speed the shaking of your hands becomes noticable in a photo. (Unless you use a tripod)

Outdoors, you should be fine in a nice day. You will have a fast enough shutter speed.

I said its for still photography because it wont stop the motion of your subject, just the shaking of your hands...

Crazydad · Jul 23, 2008

Imho definitely go with the IS. Without it I never would have got this shot

Shutter speed on that was 1/6 sec. (aperture 3.8 ISO1600). While not the best shot (still a noob and learning), at least it is something to work with.

Prodigy2k7 is right about the outdoors on a nice day, but if it is near dusk and/or cloudy do you want to take the chance of missing the shot? Plus, I think it can open up some artistic chances if you are able to slow the shutter without losing focus.

prodigy2k7 · Jul 23, 2008

Crazydad said:
Imho definitely go with the IS. Without it I never would have got this shot

Shutter speed on that was 1/6 sec. (aperture 3.8 ISO1600). While not the best shot (still a noob and learning), at least it is something to work with.

Prodigy2k7 is right about the outdoors on a nice day, but if it is near dusk and/or cloudy do you want to take the chance of missing the shot? Plus, I think it can open up some artistic chances if you are able to slow the shutter without losing focus.

Nice shot!

Crazydad · Jul 23, 2008

Thanks!

Samriel · Jul 23, 2008

I'll add some questions of my own.

1. At what shutter speeds does IS become more or less useless/ineffective? This depends on the focal length used as well, right?
2. I often read about a x-stop IS (or VR, or whatever...), but can a 3-stop IS really allow me to use 1/8s instead of 1/60s and get sharp pictures? Basically, how effective is IS in real life?
3. How many stops is the current industry standard?

reg · Jul 23, 2008

Samriel said:
I'll add some questions of my own.

1. At what shutter speeds does ISO become more or less useless/ineffective? This depends on the focal length used as well, right?
2. I often read about a x-stop IS (or VR, or whatever...), but can a 3-stop IS really allow me to use 1/60s instead of 1/8s? Basically, how effective is IS in real life?
3. How many stops is the current industry standard?

1) I have no idea what that means.

2) IS lets you use lower shutter speeds, not higher ones.

3) It's generally around 3-4 stops, but it depends on a lot of things, especially how shaky someone's hands are.

sabbath999 · Jul 23, 2008

Samriel said:
I'll add some questions of my own.

1. At what shutter speeds does ISO become more or less useless/ineffective? This depends on the focal length used as well, right?
2. I often read about a x-stop IS (or VR, or whatever...), but can a 3-stop IS really allow me to use 1/60s instead of 1/8s? Basically, how effective is IS in real life?
3. How many stops is the current industry standard?

1) yes, it depends largely on the focal length... the longer the length, the faster the shutter speed needs to be. I shoot Nikons (so basically IS=VR for me) and I find that with shorter lenses, I can handhold down to about 1/15th and get clear pictures most every time. ISO? It depends on your camera. Some cameras have good clean high ISO's, and others do not. My D300 can shoot well RAW up to 3200 ISO. Your milage may very. As far as the focal length goes, that only has to do with ISO in the fact that the longer the focal length you shoot, the faster you need to have your shutter speed to keep from vibrating. If your camera is on a tripod and your subject isn't moving, then it doesn't matter at all. If you are shooting moving subjects, then it factors into it. The rule of thumb is that you need to exceed your focal length (including crop factor) for a clear shot of a moving subject. Example... if you are shooting 200mm, and your crop factor is 1.5 (Nikon) then you are effectively shooting 300mm... therefore your shutter speed should exceed 1/300th of a second. Like all rules of thumb this has exceptions.

2) You have it reversed, IS can let you use 1/8 instead of 1/60th with smaller focal lengths... it is quite effective. Having said that, you might or might not be actually able to shoot 1/8th with it, that depends on if you have good technique. IS increases your chances of a good shot, but it doesn't guarantee it.

3) There isn't an industry standard. Cameras with IS built into them generally get 2 to 3 stops. Most good lenses get 3 stops. A few Nikon VR lenses get an honest 4 stops... I don't know on Canons exactly.

Samriel · Jul 23, 2008

Sorry, wrote confusing questions full of errors and misspells. I misspelled the IS and it became an IS, and as you noted, in the second question I actually meant the opposite - 1/8s instead of 1/60s.

Thanks for the answers, gives me a better idea of IS/VR. Don't own any VR lenses yet.

Seefutlung · Jul 23, 2008

The advantage (stops) are based on rule of thumb, which states that one should not use a shutter speed less than the reciprocal of the focal length. So if you using a 200mm lens then the slowest shutter speed one should use is 1/250 of a sec. A 20mm lens rule of thumb is 1/30.

So using a 200mm three stops mean you can shoot handheld at 1/30.
1/250 to 1/125 = One Stop
1/125 to 1/60 = One Stop
1/60 to 1/30 = One Stop

For most photography what IS does is allow the photographer to capture non-moving subjects at a higher image IQ then they would without IS.

When one runs out of high ISO, IS is most useful in capturing a sharp image which may have been impossible otherwise.

Gary

reg · Jul 23, 2008

Seefutlung said:
The advantage (stops) are based on rule of thumb, which states that one should not use a shutter speed less than the reciprocal of the focal length. So if you using a 200mm lens then the slowest shutter speed one should use is 1/250 of a sec. A 20mm lens rule of thumb is 1/30.

Don't forget to include crop factor - that RoT is based on 35mm. It may become important at longer focal lengths.

nyamy · Jul 24, 2008

oh boy
I'd better do some more reading
so much of this conversation is over my head

who knew photography involved so much math?

Samriel · Jul 24, 2008

Don't worry nyamy, for the most part it's not as hard as it seems. When people start talking about entrance pupils and who-knows-what-else in some other threads, then it gets a bit confusing (although still very interesting and informative). Just give yourself some time, and experiment with your camera.

Seefutlung · Jul 24, 2008

reg said:
Don't forget to include crop factor - that RoT is based on 35mm. It may become important at longer focal lengths.

I've read many discussions on a crop sensor versus RoT and nothing truly definitive has spring from these discussion (i.e. Yes, one must include the crop factor as part of RoT or No, crop factors do not apply to RoT.)

Although, I've not read anything which clears up RoT and crop sensors doesn't mean that there is not a definitive answer ... just that I haven't seen one. My experience and what I have read indicates that a crop factor does not apply to RoT (but I rountinely shoot lower than RoT and even practice techniques which allow lower than RoT shooting).

Gary