I've gotten some emails expressing confusion regarding the difference between the multi-aspect ratio Four Thirds sensor in the Panasonic GH1 and the standard Four Thirds sensor found in all other Micro Four Thirds cameras. This illustration ought to clear it up.
On the left (first column), you can see the relative sizes of the GH multi-aspect ratio sensor (top) and the smaller standard Four Thirds sensor (bottom), each represented by white boxes.
In the second column, one can see that the portion of the GH1 sensor used for 4:3 aspect ratio (top) is the same size as the entire standard Four Thirds sensor (bottom). Thus the image captured will be the same when in 4:3 mode, regardless of whether one uses a standard Four Thirds or multi-aspect ratio sensor camera.
In the third and fourth columns, 3:2 and 16:9 respectively, the situation changes. Here, the GH1 uses the larger sensor to keep the lens diagonal angle of view unchanged regardless of aspect-ratio. In contrast, the standard Four Thirds sensor simply crops out a portion of the 4:3 capture to make the 3:2 or 16:9 image. As a result, the diagonal angle of view is less wide, and the megapixel count drops to a greater extent.
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Chuck A · 809 weeks ago
How does the GF1 fit in here? Is the sensor similar to the GH1?
amin 67p · 809 weeks ago
The GF1 uses a standard Four Thirds sensor like the G1 and E-P1. I don't know why only the GH1 has the multi-aspect sensor so far. I think it would be a great thing to implement in all Micro Four Thirds cameras going forwards.
Linh 36p · 809 weeks ago
Hard to tell · 809 weeks ago
From DPReview:
GH1: 4/3 " (18.00 x 13.50 mm, 2.43 cm²)
G1: 4/3 " (18.00 x 13.50 mm, 2.43 cm²)
From Panasonic: G1 GH1
Image Sensor Size17.3 x 13.0mm17.3 x 13.0mm
http://www2.panasonic.com/webapp/wcs/stores/servl...
amin 67p · 809 weeks ago
ivan · 809 weeks ago
amin 67p · 809 weeks ago
MtnBiker 2p · 809 weeks ago
What are the dimensions of the sensors? The white boxes don't have any dimensions. And what is the source for the size of the white boxes? Panasonic and dpreview say the sensors are the same size for the G1 and GH1, even if they don't agree on the dimensions. My original link may have had an error http://www2.panasonic.com/webapp/wcs/stores/servl...
And more pixels doesn't necessarily make the sensor bigger.
amin 67p · 809 weeks ago
Basically it comes down to this: The difference is zero if you shoot 4:3, fairly minimal if you shoot 3:2, and starts to become more significant at 16:9. At least that is what I've noticed in use and I think is represented as such if you look at the figure shown above.
MtnBiker 2p · 809 weeks ago
A drawing shows the situation a bit better here: http://www.dpreview.com/reviews/panasonicdmcgh1/. Although I think the rotating gif on the bottom of the page is wrong.
I should add that all of this isn't terribly important, the results are what counts. And as you originally pointed out the GH1 doesn't crop from a 4/3 sensor, but uses others parts of a sensor with more pixels resulting in more pixels in the 3:2 and 16:9 formats than those formats in the other u4/3 cameras.
robotslave · 808 weeks ago
Start with a diagonal of 21.63mm, as per the m4:3 the white paper. This gives us:
4:3 - 17.3 X 12.98mm
3:2 - 18.0 X 12.0mm
16:9 - 18.85 X 10.6mm
That's effective imaging area, actual sensor size will be a bit bigger, and they're doing the sensible thing and just using a larger rectangular sensor, not chopping off the corners of the wafer (http://www.imaging-resource.com/PRODS/DMCGH1/ZSEN... so it's in the ballpark of 19.5 X 13.5mm, or 8 or 9 percent larger than the usual 4:3 sensor.
Imaging Resource almost correctly calls it an "oversize sensor" instead of "multi-aspect sensor"; the accurate, though much more cumbersome term would be "oversize sensor that can safely have defects in a few small regions in the corners".
Dwight · 809 weeks ago
MtnBiker · 809 weeks ago
MtnBiker · 809 weeks ago
Seems more likely that 3000x3000 pixels are saved to 2992 x 2992, but I have no idea how all of this really works. But downsizing images is common in most digital cameras. But I don't see why it wouldn't save 3000 x 3000, it's a smaller file than the other formats. Time to learn more how all this works.
Dwight · 809 weeks ago
Chez Wimpy · 809 weeks ago
Quido · 809 weeks ago
It seems not plausible to me that it would have a multi-aspect sensor, and instead of using the greater FOV of the 3:2 mode, it would be compensating by a tiny automatic "zoom-in"...
Quido · 809 weeks ago
improbable · 809 weeks ago
Most obviously I'd like to be able to change aspect ratio after the fact.
But also, when I get the horizon skew, I'd like to be able to rotate the picture. In 2x3 this should be possible, within the image circle, with no change in angle of view; in other formats it will still be better than cropping within the crop...
I have much more hope of seeing the first than the second, as presumably this should just involve some minor hack of the files. And I'm sure I'll hear about it here when this becomes possible!
improbable · 808 weeks ago
This is a pity, I'd like to have raw files with everything. But the camera would have to save more data from each picture, and perhaps that is why they didn't do it that way.
robotslave · 808 weeks ago
The multi-aspect sensor is not and will not be used in still-only m4/3 cameras because:
1) it is significantly more expensive than the 4:3 sensor. It has more surface area and almost certainly higher defect rates than a normal 4:3 sensor. If Panasonic ever release body-only versions of the g1 and gh1, there will be a price difference large enough to deter those who don't absolutely require video, due almost entirely to the higher cost of the multi-aspect sensor. Cost, however, is a less important reason than:
2) m4/3 still lenses are and will continue to be designed for a 4:3 aspect ratio sensor. Defects like vignetting and soft corners will affect more of the frame in the wider aspect ratio, and may show up where they were mostly absent on a 4:3 sensor, even in high-end lenses.
The 4:3 and m4:3 systems were designed as just that - *systems*. You can't change a key parameter of the system and expect everything else to work as well as before without re-engineering every component that was designed, built, and tested to that parameter.
robotslave · 808 weeks ago
amin 67p · 797 weeks ago