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01-12-2010, 01:04 PM   #1
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When does IS matter?

Trying to explain to my wife how image stabilization works I showed her some examples of IS on/off images at a range of aperture/speed settings. She then asked the question, does IS matter more below a certain speed? and I said yeah, usually less at speeds lower than the FL of the lens, e.g., 1/30th on a 50mm lens. Then, the second question I couldn't answer, then does the effect of IS diminish as the shutter speeds go up until it reaches a point where IS on/off is irrelevant? I'm going to run some test shots, but I thought I'd also tap into the experience of the Forum for some comments,
Brian

01-12-2010, 01:09 PM   #2
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you gain approximately 2.5-4 stops of light with sr on, depending on the camera/lens; the rest is up to you.

i can usually get 1/10 outta my 50mm & 135mm... no clue if you could squeeze that off without shake present. if you're shooting faster than the focal length of your lens it shouldn't matter unless you have really shaky hands, and then who knows what you'd need.
01-12-2010, 01:16 PM   #3
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yes, at some point, such as 1/2000 or 1/4000, SR will probably have almost no visible impact when hand-holding a 200mm or shorter lens.

likewise below a certain speed SR is also not going to save your ass, like 1 or 2 second exposures (although you will find the occasional boaster showing off his steady arms)
01-12-2010, 01:22 PM   #4
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Moved to DSLR forum as this is more about camera function than technique.

01-12-2010, 01:31 PM   #5
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You can't really say that at such-and-such shutter speed you will always need IS. Camera shake is very personal - I used to habitually hold a 200 mm lens steady at 1/125 without IS. But I can no longer reliably hold a 135 mm lens steady at 1/125 without IS. Best thing to do is experiment yourself with various shutter speeds, see if you can hold the camera steady for 3 shots and see what types of speeds you can reliably handle (I can occasionally do the 1/125 with a longer lens, but not reliably).

IS does become irrelevant at high shutter speeds. If the shutter speed is faster than the motion, you'll get a sharp picture. Think about capturing sports and moving objects - slower shutter speeds will show movement blur in the moving object. Faster shutter speeds will freeze the action. Camera shake is nothing more than motion, only this time it is the camera that's moving, not the subject. If you use a shutter speed fast enough to freeze the scene, you don't need IS.

That's where the traditional 1/focal length for shutter speed comes from - on average, that shutter speed should be fast enough to avoid camera shake without IS. However, it really depends on the individual person and how steady they are - everyone is different and as I've gotten older, I've gotten less steady.
01-12-2010, 01:44 PM   #6
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for IS at high shutter speeds I am almost of the impression that once you are over 1/(focal length *1.5) IS is not needed.

Also note, IS is NOT used during flash photography, or tripod use or when you are panning the camera to track moving subjects. In each of these cases IS will interfere with the image negatively, and for flash, the camera automatically shuts it down.
01-12-2010, 02:09 PM   #7
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As attack11 says, it depends on focal length and your steadiness. He is a little more sanguine and maybe a little more steady-of-hand than I am. I usually expect about 2-3 stops extension. What that means is that if I can usually hand-hold a given lens at 1/125s, SR will produce similar results with the same lens at 1/15s or 1/30s.

The best I have done with SR on is 1/8s with an 85mm lens.

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01-12-2010, 02:56 PM   #8
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you pop Diazepam pills or what? LOL



01-12-2010, 03:00 PM   #9
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Nah, just alcohol I'm sure...
01-12-2010, 03:21 PM   #10
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I think I missed a step

QuoteOriginally posted by Lowell Goudge Quote
for IS at high shutter speeds I am almost of the impression that once you are over 1/(focal length *1.5) IS is not needed.

Also note, IS is NOT used during flash photography, or tripod use or when you are panning the camera to track moving subjects. In each of these cases IS will interfere with the image negatively, and for flash, the camera automatically shuts it down.
If I'm dragging the shutter (for a variety of reasons) while using flash, where is the value in shutting down image stabilization? Wouldn't I want to keep the benefit of SR at 1/30th? I'm often shooting at about 100mm (35mm equivalent) and want a shutter speed of 1/30 to 1/60.

When replying please ignore the "inverse of focal length" rule of thumb. I have rather shaky thumbs and need all the help I can get short of lugging a pod (mono, bi, or tri) about.
01-12-2010, 03:22 PM   #11
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Haven't tried diazapam but a good IPA does wonders .......
01-12-2010, 03:25 PM   #12
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QuoteOriginally posted by glanglois Quote
If I'm dragging the shutter (for a variety of reasons) while using flash, where is the value in shutting down image stabilization? Wouldn't I want to keep the benefit of SR at 1/30th? I'm often shooting at about 100mm (35mm equivalent) and want a shutter speed of 1/30 to 1/60.

When replying please ignore the "inverse of focal length" rule of thumb. I have rather shaky thumbs and need all the help I can get short of lugging a pod (mono, bi, or tri) about.
remember SR does nothing for subject motion, only your own body motion.

so if you drag the shutter to capture subject motion, you would still want SR on to keep the still objects in focus

if however you want the whole scene to be blurry, then you will benefit by turning SR off.
01-12-2010, 04:33 PM   #13
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I've been getting sharp pictures (of static subjects) at 1/30s and 90mm with SR on. I got one very blurry one and then noticed SR was off. It does give you a stop or more of room.
01-12-2010, 09:50 PM   #14
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SR is active with flash

QuoteOriginally posted by Lowell Goudge Quote
for IS at high shutter speeds I am almost of the impression that once you are over 1/(focal length *1.5) IS is not needed.

Also note, IS is NOT used during flash photography, or tripod use or when you are panning the camera to track moving subjects. In each of these cases IS will interfere with the image negatively, and for flash, the camera automatically shuts it down.
On my K10D, SR definitely remains active with the built-in flash turned on. I just took a shot and checked the EXIF. In addition, the little hand appeared in the viewfinder, indicating that SR had stabilized.

I'm not sure how SR would interfere with the image. If you're shooting a normal flash, at or near the maximum sync speed of 1/180, it may not be necessary, but I don't see how it could detract from image quality.

If you're dragging the shutter to bring out shadows via ambient light, SR would definitely help.
01-13-2010, 06:10 AM   #15
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the issue would be SR at low speeds, with fill flash, where you have an image and then the flash fires perhaps making a double
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