I have to admit that, like Scott, I am a bit confused as well. I am not dissing IS, just trying to understand when it is really useful.
In the last two Africa shots of Christojo58--First one he said he wouldn't have gotten without IS. But it is taken at 100mm at 1/160 sec. At that shutter speed with a 100 mm lens, wouldn't it have been sharp hand held without IS?
Second shot is at 1/1000 second. Again, at that shutter speed, is IS really doing anything.
My questions here are sincere and not meant to pull anyone's chain. Help me understand IS and its uses better.
I agree with Lorin and Scott... I don't mean to offend the photographers, but IS shouldn't really be necessary for shots less than 100mm with shutter speeds greater than 1/x (where x is the focal length).
I do think that IS is great, but I was expecting to see images showcased here at 300mm or 400mm with shutter speeds of 1/200 or 1/100 or less... that to me is where IS shines.
kordell wrote:
I agree with Lorin and Scott... I don't mean to offend the photographers, but IS shouldn't really be necessary for shots less than 100mm with shutter speeds greater than 1/x (where x is the focal length).
... unless you are on a crop sensor and your focal length is an effective 1/(1.6*FL) or 1/(1.3*FL).
Under standard, indoor, incandescent light, it can be fairly tough to get a Tv of 1/60th. If you're shooting at 50mm, that's 50*1.6 = 80, so you're behind the proverbial eight ball. IS helps in situations like that.
Personally, I find IS helps me during the day at really high shutter speeds for panning when I'm shooting my dog sport - it helps me keep the center AF on target more reliably.
I don't own a P&S with IS, but IS is extremely popular on them, and people often benefit from it even though they're shooting at a focal length equivalent of less than 100 or 200mm. The fact that they're usually holding the camera out away from their body rather than keeping it tucked in the way you shoot an SLR only adds to the necessity of IS on P&S's.
I can imagine grab shots of waterfalls where someone wanted to to get the look of flowing water, but didn't have a tripod available.
The benefits of IS are certainly more obvious at longer focal lengths, but I think it's a bit of a stretch to deem it completely unnecessary at shorter focal lengths.
IS can make the difference between throw-away and keeper shot, just due to handshake blur alone.
and, it's not just reduced handshake the IS helps with.
Here's an image shot with a 70-200 @ 180mm, 1/2500. IS on.
With the boat cruisin' over the water, especially when the water gets a bit choppy, it can be a pretty bumpy ride. Keeping the subject in the frame can be quite a challenge in and of itself, especially when you wanna shoot tight without chopping off body parts due to the bumps of the boat. Enabling IS helps in even keeping the subject in the frame sometimes!
Scott Sewell wrote:
...I'm also curious if it really helped in BrianO's first and second images. To me, those shots don't look very sharp and with a focal length of 55mm and shutter speeds of 1/60 adn 1/80, it would seem to me that IS didn't really play much of a factor in those images. Again, I don't use IS so I'm not questioning it's usefulness...just trying to get a better handle on its benefits.
As I mentioned in my first post, there was a focus issue on those shots. Also, since it was my first day with that lens, I was shooting wide open just to see what it looked like. Those two factors are what I think results in the lack of sharpness.
That said, if you look at the picture of the squirrel, you'll note that the rail on which it is sitting is pretty sharp. If you look at the lines of the wood grain, there isn't any noticable motion blur. For me, taking quick shots of critters without getting motion blur has been problematic; not any more.
Oh, BTW, on a 20D that 55mm is equivalent to about 88mm, so handholding it at 1/60 and 1/80 is less than ideal.
Scott Sewell wrote:
...Here are a couple of fireworks images that are hand held without IS. I'm trying to understand how IS might have helped in a situation like this.
I wasn't there, but did the trails of the embers really zig-zag like that?
This shot of two fawns was taken in the fading evening light. It was taken with a 500/4 plus a 1.4x on a 1DII and was hand held. The two fawns stuck their heads into open view for just enough time for me to squeeze off two shots. The shutter speed was 1/30. Because I wanted to create a soft and gentle look for the fawns, I thought that the actual shot was a bit "too sharp", if there is such a thing, and I actually applied a small amount of gaussian blur in processing to give the shot a softer effect. Perhaps, I could have gotten the shot without IS, but I doubt it.
Contrary to the thoughts of others expressed here, I find that IS still has value even at higher shutter speeds. The value may decrease as shutter speed increases, but it is still there. The best quick description I've read about the value of IS said something to the effect that IS can have value in any situation where a tripod would have value. Even at higher shutter speeds, there are still effects of camera shake. Those effects might not be as great as they would be at slower shutter speeds, but they are still there, and, even at higher shutter speeds, I can see the difference in my hand held shots with and without IS in the same way that many would argue that they can see the difference between hand held shots and those shot with a tripod at higher shutter speeds. The shot below of the eagle is an example of this. It was taken on a dreadfully cloudy day with the 500/4 and 1.4x on a 40D hand held. The shutter speed was 1/250. Without IS I might have gotten an acceptable shot, but, without IS, I'm confident that there would have been a significant difference in sharpness.
Further, I find IS to be a significant advantage in acquiring and maintaining focus while shooting action with a long lens. With the image in the view finder not jumping around, it is so much easier to acquire focus initially and also to keep the focus point where I want it on a moving subject. I won't own a lens over 200 mm without IS, and, even if there are situations where the need for IS is less than in other situations, it is always still there for those situations where its value is greater.
Hmmmm...I'm not an expert but I think some of you are not understanding what IS does as other posters have hinted at.
For example, I'm almost nearly certain at a shutter speed of 1/2500 IS is doing absolutely nothing for you. You do realize that means, if mechanically possible, the shutter would open and close TWO THOUSAND FIVE HUNDRED TIMES in one single second. This is what is creating the sharpness not IS. The flash of light to the sensor is so fast that it is actually slicing out a single frame in time. Much like film in a video camera.
I would guess at 1/2500 of a second you could set the timer on your camera and literally throw it into the air and spin it as violently as you possibly can and it would take an image where the motion was frozen and sharp when the timer went off. With or without an IS lens.
I believe IS benefits begin around the slower shutter speeds; i.e 1 / focal length. Also, I've read numerous times that the crop factor shouldn't be applied as 1.6 when doing the camera shake rule; i.e you don't need 1/160 on a 100mm lens on a crop camera. However, I haven't found anything conclusive on wether or not this is true.
crockett wrote:
Hmmmm...I'm not an expert but I think some of you are not understanding what IS does as other posters have hinted at.
For example, I'm almost nearly certain at a shutter speed of 1/2500 IS is doing absolutely nothing for you.
I didn't see anywhere in this thread where anyone suggested that IS would give a sharper image at 1/2500 than a non-IS shot.
I did read where Ariel said IS helped keep a steadier image in the viewfinder for a shot that was made at 1/2500.
"With the boat cruisin' over the water, especially when the water gets a bit choppy, it can be a pretty bumpy ride. Keeping the subject in the frame can be quite a challenge in and of itself, especially when you wanna shoot tight without chopping off body parts due to the bumps of the boat. Enabling IS helps in even keeping the subject in the frame sometimes!"
Lava flow into the ocean last summer, Big Island, Hawaii. It's dusk, the light rapidly failing. There's not a tripod to be found, and the flow is far enough away that I need all the focal length and aperture that my 70-200 f/2.8 IS can give me.
LDR99 wrote:
I have to admit that, like Scott, I am a bit confused as well. I am not dissing IS, just trying to understand when it is really useful.
In the last two Africa shots of Christojo58--First one he said he wouldn't have gotten without IS. But it is taken at 100mm at 1/160 sec. At that shutter speed with a 100 mm lens, wouldn't it have been sharp hand held without IS?
Second shot is at 1/1000 second. Again, at that shutter speed, is IS really doing anything.
My questions here are sincere and not meant to pull anyone's chain. Help me understand IS and its uses better.
I don't see IS as just being useful when you're shooting on the edge of acceptability (eg: wide open at 1/30th). One thing IS helps do is preserve your ability to shoot quality in less than ideal conditions. So, while I did have a stop or two to play with, I believe that the quality of the first shot in that light would not have been there without IS.
In the second shot, I was panning and using IS in mode 2.
BrianO wrote:
I wasn't there, but did the trails of the embers really zig-zag like that?
Actually, I have shots where the trails are almost perfectly straight, but yes the trails of the green embers did zig zag and in the second shot you'll notice that a slight right-to-left breeze was blowing the embers to the left as they trailed out.
Again, I didn't ask my questions to get the IS lovers all lathered up. I was hoping we could discuss this so I could better understand how IS would have helped in shots like these fireworks shot or other images where extreme blur is the intended outcome (like the cool image Ariel posted of the dancers). To me it seems contradictory to what IS does or is for. With the kinds of cool heli shots Mark posted...I totally understand how one can use IS to have shutter speeds slow enough to blur the blades yet keep the body of the helicopters sharp.
Scott Sewell wrote:
Yakim, I'm not questioning whether you're happy with those images or not. I'm just trying to figure out how IS might be useful when shooting like that. Honestly, it's a new one to me and I'm trying to find somenoe who might be able to explain it.
Explanation is very simple. I can't take such shots at these shutter speeds (1 sec, 2 sec i.e. significantly under the 1/FL rule) handheld without IS. Therefore IS is very valuable for me.
I must not be asking the question right or something is amiss.
I thought IS was suppose to help in situations where the shutter speeds were so slow that without IS the images would be blurry. So, one would use IS to, say, help have a sharper images in a low-light situation. In effect, doesn't IS offer the equivalent up a couple of shutter speed steps? If that's the case, how is it beneficial in images where blur is the intended effect? Maybe I'm looking for "I just leave it on" answers. I don't know. But considering blurred images like the fireworks or those in the original post, or Ariel's...I honestly do not understand how one would be able to say IS is actually helping in those sitautions. I'm just not following the logic here; seems counter to what I always thought IS was for.
Ariel...I'm shooting you a PM. Maybe you can help clarify this for me outside of this thread.
Scott Sewell wrote:
I must not be asking the question right or something is amiss.
I thought IS was suppose to help in situations where the shutter speeds were so slow that without IS the images would be blurry. So, one would use IS to, say, help have a sharper images in a low-light situation. ...If that's the case, how is it beneficial in images where blur is the intended effect?
I think you're asking the question right. The answers may not be clear, though.
Look again at the carnival pictures. The moving part of the farris wheel (I think that's what it is) is totally blurred for a "streaks of light" effect, yet you can still make out the nuts and bolts on the axle. Without IS or a tripod, that part of the equipment wouldn't have been at all sharp, and the light streaks would have been jagged.
Same with the shots of the dancers; yes, there is motion blur, but the blurred shapes are smooth. Handheld without IS, they might have been jerky looking.
While IS would be nice to have, I don't believe in it being the factor in making or breaking the shot for wide angle to normal focal length, only for telephoto. Note that I'm not trying to pass it as a fact, it's just my personal opinion.
