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Old May 10, 2009, 7:00 AM   #1
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Default Image stabilization and resolution

I wonder if optical image stabilization is effective enough for preventing blur from camera movement if working with very high resolutions.

Let us assume a certain identical normal camera movement with a 26 megapixel camera vs. an 8 megapixel camera, both equipped with identical optical IS systems and optical lenses etc. (all equal).

If the resulting photos become a little blurry, will still the 26 megapixel camera bring a photo of higher detail?

If there will always be a certain blur in photos, what is then the point with working with cameras in "ultra-high" resolutions if the IS cannot fully prevent camera movement?
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Old May 10, 2009, 7:44 AM   #2
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The kind of Image Stabilization systems in the cameras we talk about here are reactive systems, which means that some camera movement must occur before the system can compensate for it. If you use an image sensor with a high enough resolution, you will see some motion blur, though far less than you would see had there not been an image stabilization system.

But there are plenty of things that affect image quality, like the resolving power of a lens, that are likely to introduce as much, possibly even more uncertainty into an image than the lag time between when a camera moves in a particular direction and when the image stabilization system compensates for it.
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Old May 10, 2009, 9:52 AM   #3
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Quote:
Originally Posted by njetski View Post
If there will always be a certain blur in photos, what is then the point with working with cameras in "ultra-high" resolutions if the IS cannot fully prevent camera movement?
You are talking apples and oranges here. IS and megapixel resolution aren't related and provide different capabilities. So assuming that a lower mp count will give you exactly the same quality as a higher mp count camera just because the IS system will allow a certain blur isn't a correct assumption. It's like saying a rat and an elephant must be the same because they are both animals.

As TCav pointed out, there's a huge number of other factors that enter into the equation. There's actually more to the concept of "resolution" than just mp also - two different cameras with sensors that have the same mp may not resolve lines the same way (i.e., one can differentiate finer detail than the other) even with the same quality of lens on them. And he is right that the lens plays a huge part.

What you do with the pictures will also dictate whether you get a better picture from a higher resolution camera - if you always print 4x6 prints and use the full frame pictures as screen savers, then you probably don't need a 26 mp camera. However, if you print posters or crop significantly (birders and macro shooters come to mind), then having more mp would be very helpful.
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Old May 10, 2009, 10:36 AM   #4
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If you use an image sensor with a high enough resolution, you will see some motion blur [...]
So, ultra-high mp cameras need a more sophisticated IS.
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Old May 10, 2009, 2:17 PM   #5
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Quote:
Originally Posted by njetski View Post
So, ultra-high mp cameras need a more sophisticated IS.
They need a more sensitive IS, but they also need better lenses. And they need better lenses more than they need better IS.

A lot of things happen when you make a significant increase in the resolution of an image sensor. One of which is that the flaws in a lens become much more obvious. Compared to the results of a soft lens projecting an image into a 24MP image sensor, the results of an IS that's not quite sensitive enough is slight.

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Old May 10, 2009, 9:07 PM   #6
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If you assume having a lens and camera capable of effectively using that much Mp you can reduce the variables and just talk about Mp versus stabilization.

Say you took a class photo with your 26Mp camera and made a 20 X 30 print for the wall. People would look at the photo closely to see the individuals. Effectively you would be taking a telephoto shot of the individual with a lower Mp. Telephoto requires better stabilization, so in this instance you would require better stabilization to handhold the shot. Take a 26Mp shot of a sunset and make the same sized print and it would be viewed at a much greater distance. The same sharpness would probably be required as for an 8Mp photo printed 8 X 10 and viewed at arms length of the same subject. The extra MP would give you a smoother photo printed 20 X 30, but the stabilization requirement would probably be the same.

If you want to use extreme crops or large prints with fine detail you indeed need better stabilization for the higher MP shot. I don’t think any photographer worth his salt would take a class photo for a large print and handhold the shot. If you need the extreme detail you probably want a tripod. But most people probably display or print the 26Mp image at the same size as they would an 8Mp image. In which case the stabilization requirement is the same. The stabilization isn’t at all useless nor is the extra Mp. But to get all the detail available from a good lens and 26Mp you would want to use a tripod, especially at longer focal lengths. Extra Mp with a good lens and camera offers you that option.

You often can’t get all of the detail available handholding a long telephoto shot with an 8Mp superzoom. My old FZ10 was only 4Mp and 12X, and I still used burst and a super steady hold in limited light to try to get all the detail available – and often failed. And the FZ10 held f2.8 all the way to 12X. That doesn’t mean it was foolish of me to buy a whopping 4Mp. It means that everything has limitations and you have to work with them. If I waited for stabilization to completely offset Mp I would still be waiting for a camera. Or limit myself to fisheyes.
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Old May 10, 2009, 9:59 PM   #7
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Quote:
Originally Posted by njetski View Post
So, ultra-high mp cameras need a more sophisticated IS.
I disagree with this as a blanket statement. If you look at two shots, both full frame and using the same aperture/shutter speed and sized the same (i.e., both printed 8x10), one that's been taken by a 24mp camera and one that's been taken by a 6 mp camera you would not see any more camera shake in the one taken with the higher mp camera. Image stabilization only affects camera shake, not resolution or other image quality aspect. I don't think you'd see much difference as far as camera shake between the two even if you looked at them at 100% crop (i.e., cropped both of them to a 600 x 600 mp sample without resizing at all). You might or might not see additional detail with the 24 mp camera's picture, depending on the lens. The amount of the subject you would see in the 24 mp camera would be significantly different - you would see less of your subject (the image would be bigger). But I don't see where you would necessarily need a better IS capability.
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Old May 11, 2009, 2:50 AM   #8
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The OP is absolutely correct.

The higher the resolution the more important everything that goes towards producing a sharp image becomes. This absolutely includes how good your stabilisation is, whether it be tripod or IS.

Every link in the chain is important, and the most important link for any given chain is it's weakest link. That may or may not be your stabilization system, it may or may not be your lens, or your RAW converter, or your sharpening technique, or how you print, etc.

For anyone who doubts this have a read of this first:

http://www.luminous-landscape.com/essays/mf-easy.shtml

And have a read of this too:

http://www.imx.nl/photo/technique/technique/page40.html
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Old May 11, 2009, 8:42 AM   #9
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But once again, all other things being equal, when you increase the resolution of an image sensor, there are issues more significant than the sensitivity of the image stabilization system, when trying to eliminate (or even reduce) blur.

In Image Engineering's Test for Image Stabilizers (Boris Golik), the method of measuring blur is the Modulation Transfer Function (MTF), a test many of us are familiar with (or, at least, have heard of) when measuring the resolving power of a lens. Needless to say, when you increase the resolution of the image sensor, you increase the MTF of the photographic system as a whole. But an inevitable result is that when you improve one component in a system, frequently, some other component becomes the weak link. Increasing the resolution of the image sensor would cause the lens to be the limiting factor in any MTF measurements. This would be easy to confirm since the blur caused by the resolving power of a lens would be circular, while the blur caused by camera shake would be linear. (Motion blur due to camera shake is caused by Physiological Tremor which has a frequency of 8-12Hz, and is oscillatory, meaning that, during a short time, is a back-and-forth movement, so motion blur due to camera shake is mostly linear.)
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Old May 11, 2009, 3:11 PM   #10
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Then, from this discussion, it would follow that if you turn IS off, a picture taken with a 14 mp camera would show more camera shake than a picture taken with a 6 mp camera, assuming the same lens, and shutter speed?
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