Must be same as GH2

It depends on aspect ratio. 16:9 aspect ratio on GH(1)2 is around 1.86. 4:3 is 2x.

Edit: I never did the maths myself, just gathered info from around the place.

This is an interesting topic. It seems like there is still a confusion about the crop factors of GH1 and GH2 and GH3 and BMC when shooting video at 16:9 aspect ratio. There is no stable information on internet ... just individual opinions.

There's a BIG difference between 1.86x and 2x . So which one is it?

I indeed tried to compare pics of the FF camera vs GH1 while using two different lenses with focal lengths in the proportion of exactly 1:2 (so 25mm vs 50mm or 100mm vs 200mm). The pics of the same, static subject were shot from exactly the same spot using tripod.

Using 3:2 ratio on the GH1, its crop seemed to be slightly beyond 2.0 mark, 1.9 or slightly less.

However, I have not tested anything in the optical laboratory and on the real test charts. The effective optical focal length of the single lenses may also have some tolerances compared to declared one (like 50mm lens could actually perform as 49,3mm or so) and besides all, @kronstadt the difference between 2.0 and 1.86 is indeed not so big- it's barely noticable, put the tripod just a touch closer and you have 2.0 crop. To be honest, I don't really care for the mathematical values, it is nearly crop 2.0 and that's it speaking only for my own.

@cbrandin What... you are correct.

I've just tried to test it again
GH1+Canon FD 100mm f/2 vs Nikon D800+Nikkor Ai-S 200mm f/4
This time on sturdy-like-hell tripod and object quite far away.

and GH1's crop in 3:2 ratio is just slightly beyond 2.0 mark, the GH1 had again very, very slightly wider FOV than the D800 (just as when I tested it before). Something like 1.95 or higher, definitely not 1.86

@cbrandin The number 1.86 probably comes from the fact that GH1's sensor covers a slightly larger image circle than the native 4:3 image aspect ratio of an usual µ4/3 sensor. Thanks to this fact, the GH1 14 megapixel sensor is capable of recording images in native aspect ratios of 4:3, 3:2 and 16:9 with no cropping, so it also has the same angle of view and maximization of pixel count in any particular format.

So, effectively, the GH1 sensor has 14 megapixels, but it is never used to its full capacity (max. up to 12.1). It also means that the sensor of the GH1 (and also of the GH2) would reproduce in its full size 1.86x magnification, but effectively - it never does it, so the crop is also not 1.86 but quite near by 2.0

@kronstadt so, the answer is kind of long, but important for you is the fact that you can count crop 2 as rule of thumb both for the GH1 as well for the GH2.

If anybody is interested in downloading out-of-camera JPEG, send me PM please.

You are right about the 4:3 ratio. The GH1/2 dimensions are 17.3x13mm for a 4:3 image. That means the ratio against a 4:3 image within a FF 35mm frame (32x24mm) is 1.85:1.

For video, it seems to me that what is most meaningful is the angle of coverage you can expect along the horizontal axis in a 16:9 aspect ratio frame. Thus the most appropriate ratio to use for calculating relative lens focal lengths for 35mm vs. 4/3rds would be 1.91:1.

Exactly, there is indeed slight difference in FOV between different lenses of same focal length. Therefore, I agree with @stonebat and tend to keep mathematic thinking simple: 2x
And I would say it does not sound stupid at all what you wrote, as in the field conditions it is negligible error....put the tripod just a tad closer or further away and there we got it.

Speaking only for my own, it was good to have had this thread and the debate about the crop.