GH3 What's the real sensor size/ focal lenght lens difference between GH2 and GH3

[Barry_Green]

If the aspect ratio is exactly the same, then the horizontal (or vertical) is a directly comparable measure. But if the aspect ratio is different, then yes, the diagonal becomes the only number you can use (or, by extension, the area).

 

[Shenan]

You're right, my geometry is quite rusty. I checked that for the same exact aspect ratio, the diagonal multiplier (crop factor) applies just as well to the horizontal and to the vertical measurements. Thanks for pointing that out.

 

[BitMaestro]

Wow, this thread blew up in the last 24 hours. Forgive me for combining responses to several posts...

In photography we are often more concerned with linear resolution than area - i.e, Micro 4/3 is called a 2x crop (linear), not a 4x crop (area).
So we're talking about a 8% larger sensor size on the GH3 in linear terms.

Yes, I was merely addressing the OP's statement that, "Heard that GH3 has about 10 or even 16% smaller sensor than GH2, what is true?" i.e. yes, that 16% figure is true "from a certain point of view" (to quote Obi-Wan).

2.18x crop factor is almost as 'small' as the BMCC... Not that you cannot create beautiful images with it (as can be seen from the BMCC footage), but didnt think the difference was that big...

BMCC has a crop factor of 2.38 (relative, again, for consistency, to a 3:2 photography frame). Its IQ advantage comes from, among other things, 13 stops of DR.

typically a diagonal measurement is not one people will think about in the field.

Perhaps, but since the OP asked about crop factor -- "As we all know the GH2 crop factor is 2.0x ( for full frame ) and what's the factor for GH3?" -- and crop factor is defined as the ratio of the diameter of the image circle (i.e. diagonal), that's the question I answered.

Ok so basicly the sensor is 18% smaller, but the width is only 8% smaller making the effictive crop factor 2.0x?

No. See my previous post. Relative to the standard 3:2 photography frame, when the GH3 is shooting 16:9, it has a CF of 2.18. Additionally, but also separately, when both the GH2 and GH3 are shooting 16:9, the GH2 uses an area that is ~18% larger than the GH3, but this comparison of sensor area between the GH2 and GH3 has no bearing on the GH3's crop factor relative to a 3:2 photography frame. a) the first calculation is between the GH2 and GH3, whereas the second is between the GH3 and a full photography frame; and b) the first calculation is area, whereas the second is image diagonal.

You're right, my geometry is quite rusty. I checked that for the same exact aspect ratio, the diagonal multiplier (crop factor) applies just as well to the horizontal and to the vertical measurements. Thanks for pointing that out.

Pythagoras FTW! :happy: - Mark

 

[FrameFarmMedia]

"As we all know the GH2 crop factor is 2.0x ( for full frame )

The GH2 has a crop factor of approx 1.8 due to an multi-aspect oversized M4/3 sensor (doesn't crop 4:3 to get 16:9). The AF100 and GH3 has a crop factor of 2.0 because they lack the multi-aspect but are standard M4/3 sensor size.

 

[BitMaestro]

The GH2 has a crop factor of approx 1.8 due to an multi-aspect oversized M4/3 sensor (doesn't crop 4:3 to get 16:9). The AF100 and GH3 has a crop factor of 2.0 because they lack the multi-aspect but are standard M4/3 sensor size.

So, first, that's not me. You're actually quoting me quoting the OP.

Second, as far as I'm aware, the AF100 uses the same oversized sensor that the GH2 uses, not the standard 4/3 sensor that the GH3 uses. (See Barry's post here.)

Third, if you're going to use the non-standard 3:2 photography frame cropped down to 16:9 as the basis for your comparison, the actual numbers are: 1.91 for the GH2's multi-aspect sensor when shooting 16:9 vs 2.08 for the GH3's non-multi-aspect sensor when cropped down to 16:9. (It's not a direct ratio because, in one case, you're cropping from 3:2, while in the other case, you're cropping from 4:3.)

Mark

 

[Barry_Green]

The GH2 has a crop factor of approx 1.8 due to an multi-aspect oversized M4/3 sensor

Only when shooting 16:9 aspect ratio. When shooting 4:3 it has a 2.0 crop.

the AF100 and GH3 has a crop factor of 2.0 because they lack the multi-aspect but are standard M4/3 sensor size.

No, the AF100 is an oversized sensor. Not as oversized as the GH2 is, but it's still oversized, it's 17.8mm wide.
The GH3 is 17.3mm wide.