335 words on Photos
Just a little photo geekery of the modern kind for a change: My dad got himself a nice 35-105mm lens for his digital SLR. A neat feature of that lens is its image stabiliser. Which – the ads claim – will give you the ability to gain one to two stops just because it is stablised. Which should mean that you can hold exposure times twice as long as the conventional wisdom suggest without going blurry.
So far I’ve just been very impressed with how well images with that lens worked out even in low-light situations. But Richard and me gave it a little unscientific test during the holidays. This was done by shooting a bit of christmas decoration at ambient light while fully zoomed in.
105mm on one of these popular ‘cropped’ digital sensord correspond to roughly 160mm for traditional 35mm lenses. And I learned that a good guess usually is that the inverse of the focal length is about the time you can hold free handedly. I.e. at 160mm, I’d consider it advisable to go for 1/160s or shorter. And hence we set the camera up to shoot at 1/40s, hoping to see a difference between photos taken with and without the image stabiliser. And with a bit of goodwill they can be seen. Stabilised image:
This is just a single shot of course and the difference isn’t huge as you are seeing a crop that gives you the camera pixels (enjoy the ISO 800 noise as well), so it isn’t exactly conclusive evidence, but it reflects my impression that the feature makes a difference.
And of course I love the way that image stabiliser works: It’s just a ring around the lens that starts rotating as soon as you tell the camera to focus. The angular momentum generated by that makes it harder to move the centre of the lens out of the axis the lens points at, thus giving the extra stabilisation. No fancypants electronics needed. Just honest to goodness physics.
I love the image stabilization in my new pocket camera… I could never go back to a “regular” lens again.
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