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09-27-2016, 05:34 PM - 1 Like   #1
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Olympus: Earth’s Rotation Limits Image Stabilization to 6.5 Stops Max

Down in the comments - they add some basis for the comment...
QuoteQuote:
Bob Thane

Sorry, linked a site and my comment's in moderation - here's just my written explanation.

Let's say that for 7 stops IS we'd need a one second exposure. In that second, your position has rotated by about half a kilometre, assuming you're at the equator. This is about 0.0042 degrees that the gyroscope is now off by. Let's assume we have a 24 megapixel sensor with a lens that has a field of view of 5 degrees. For there to be 1 pixel of blur, the lens would have to shift by 0.00125 degrees. The error in the gyroscope is significantly larger than this, so I can definitely see how the Earth's rotation is a factor here.

Of course, the numbers will be different. Different exposure times, different sensors, different lenses, and different positions on the earth. But it's in the right order of magnitude for me to find this claim quite plausible.



09-27-2016, 06:36 PM - 1 Like   #2
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LOL!

Pentax can solve this! With GPS location data, compass pointing angle and gravitational direction data, Pentax cameras know how the camera and scene are rotating.

Compensating for the effect of the Earth rotations is exactly what Astrotracer does.
09-27-2016, 07:07 PM   #3
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Coriolis Effect


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09-27-2016, 07:12 PM   #4
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QuoteOriginally posted by photoptimist Quote
LOL!

Pentax can solve this! With GPS location data, compass pointing angle and gravitational direction data, Pentax cameras know how the camera and scene are rotating.

Compensating for the effect of the Earth rotations is exactly what Astrotracer does.
If only the electronic compass was accurate enough to do so. It can err by as much as 15 degrees.

09-27-2016, 08:54 PM   #5
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If I remember my basic met properly, the Coriolis Effect only kicks in for a moving object, and only for an object changing latitude. Somebody shooting from a fixed position should be immune.
09-27-2016, 09:10 PM - 1 Like   #6
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Seems to me there are too many arbitrary assumptions. For one why a 1 pixel blur? if this is the criteria we are not doing photographs where SR is a consideration. Ditto a 1 second exposure. And even w/o a detailed analysis intuition suggests this explanation/science is (very) implausible.
09-27-2016, 09:39 PM   #7
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QuoteOriginally posted by dms Quote
Seems to me there are too many arbitrary assumptions. For one why a 1 pixel blur? if this is the criteria we are not doing photographs where SR is a consideration. Ditto a 1 second exposure. And even w/o a detailed analysis intuition suggests this explanation/science is (very) implausible.
I agree.
09-28-2016, 06:15 AM   #8
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QuoteOriginally posted by dms Quote
Seems to me there are too many arbitrary assumptions. For one why a 1 pixel blur? if this is the criteria we are not doing photographs where SR is a consideration. Ditto a 1 second exposure. And even w/o a detailed analysis intuition suggests this explanation/science is (very) implausible.
The point is that if you read the data from the gyroscopes inside a camera sitting on solid ground, that data will say that the camera is slowly spinning (because the Earth is turning). The SR system will try to remove the effects of that measured spin on the image. If one is taking a picture of the stars, removing the spin of the Earth is great (that's what Astrotracer does). But if you are taking pictures of landscapes, buildings, people, etc. who are also spinning with the camera once every 24 hours, the SR is adding blur to the image.

The amount of blur (in pixels) added by the SR system's "misinterpretation" of the gyroscope data depends on a lot of factors (sensor pixel size, focal length, exposure time, and pointing direction). For a 20 MPix M43 camera (e.g., the latest Olympus camera), the added blur would reach 1 pixel (worst case) for a 100 mm lens after 0.6 seconds or a 200 mm lens after 1/3 of a seconds.

Now whether 1 pixel of added blur is noticeable or unacceptable really depends on the subject matter and the photographer. But that subjectivity is always going to be an issue with both the 1/focal length rule of thumb for handheld photography as well as different photographers experience with how many stops SR actually provides.

The deeper point is that the motion of the Earth does affect SR by measurable amounts for telephoto lenses although the subjective effects are arguable.

09-28-2016, 08:02 AM   #9
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QuoteOriginally posted by monochrome Quote
If only the electronic compass was accurate enough to do so. It can err by as much as 15 degrees.
Actually, quickie calculations suggest that compass data within ±15 degrees is enough to correct at least 75% of the effect of Earth's rotation on SR (although it's not good enough to get good results on the longest of astrotracer exposure times).
09-28-2016, 08:34 AM   #10
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Who cares what Olympus says?

It's an untestable theory, you can't prove a negative, and you don't know what you can do until you try.... all of those things make it pompous nonsense.

Pompous nonsense that get's you exposed as an idiot when someone does what you say they couldn't be done.
09-28-2016, 08:58 AM   #11
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Is this why my night sports shot are blurry?
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