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Old 26th April 2012
whatapicture whatapicture is offline
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Aspect ratio

Hi all

I recently tried out my G3 with a different aspect ratio, my favourite being 3.2 which is very close to 35-mm neg size. When I checked the crops, they seemed to have a tad more sharpness than the 4.3 ratio pics which has the highest definition. I read some where that changing the ratio also reduces the number of pixels on the sensor. Could any one explain this to me in simple terms please.

Thanks

Pete
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Old 26th April 2012
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Re: Aspect ratio

The different aspect ratios simply crop the image. Using the 3:2 ratio will crop off a bit from the top and bottom. The sensor itself remains the same, but the other aspect ratios will only save part of the image from the sensor to the memory card, so you're not using all of the pixels on the sensor. You could accomplish the same thing by setting the camera to the native 4:3 aspect ratio and cropping later in your computer.

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Old 26th April 2012
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Re: Aspect ratio

Thanks Hal

I will try that, also, is it true that when you change the aspect ratios on the GH1 & GH2, pixel counts on the sensor remain the same.

Pete
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Old 26th April 2012
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Re: Aspect ratio

Quote:
Originally Posted by whatapicture View Post
Thanks Hal

I will try that, also, is it true that when you change the aspect ratios on the GH1 & GH2, pixel counts on the sensor remain the same.

Pete
No, the GH1 and GH2 are unique amongst 4/3 cameras in that they have an oversized sensor, the whole of which is never in use at the same time. It allows the camera to optimize the aspect ratio to the image circle, hence the 16:9 ratio uses a longer portion of the sensor than the 4:3 ratio. The result is that on the GH2 16:9 format is about 2mp more than it would be if just cropped from a 4:3 image. Besides a larger image area and more pixels you also get a slightly wider angle of view from the lens. It's quite a useful trick which makes the most of the image circle. The 3:2 ratio also has slightly more pixels than would be the case if cropped from a normal sensor, but the advantage is less than with 16:9. 4:3 and 1:1 are no different than any other 4/3 sensor.
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Re: Aspect ratio

There is a nice diagram of the GH2 aspect ratios here:

http://forums.dpreview.com/forums/re...ssage=36396593

As John explains, it's a bit more complicated as far as how much cropping is taking place. And it is a very nice technique for getting the largest possible image at different aspect ratios with only a slight increase in the size of the sensor. It's too bad this hasn't caught on with other manufacturers/models.

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Old 27th April 2012
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Re: Aspect ratio

Thanks Hal

The diagram looks complicated but after some scrutiny I now understand it. Agreed, its a very useful feature and I love the 3.2 for my landscapes.

I guess other manufacturers rely on us to crop in PP, but its not the same thing.

I can crop on my Nikon but its not changing the aspect ratio in camera.

Pete
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Old 27th April 2012
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Re: Aspect ratio

I grew up with 35mm, and tend to "see" the world in 3:2. I love the multi-aspect sensor of the GH2 for that very reason.
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Old 30th April 2012
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Re: Aspect ratio

the g3 sensor's physical aspect ratio is 4x3. all of the sensor's pixels are used when you set the camera's aspect ratio to 4x3. when you set the aspect ratio of 3x2, pixel information from top and bottom rows is eliminated from the saved 3x2 file. more pixel rows are eliminated when you set 16x9 aspect ratio. if you put your camera on a tripod and take make exposures of a single scene at 4x3, 3x2 and 16x9 aspect ratios you will see this clearly.
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