Tuesday, 15 March 2011

GH1 vs G1 formats and RAW pixels

Having recently acquired a GH1 to replace my G1 camera one of the things I've been keen to test out is the difference between sensors of both cameras. The GH1 has a significantly different sensor to the G1 and gives significantly different results when used in RAW and changing the recording Aspect Ratio. I first read of this about 2010 on a page by Ian Burley here. I'm not sure if Ian has updated that much, but the diagrams initially didn't mean a lot to me.

Thus I thought I'd do this and publish my results of actual photographs

It has been documented elsewhere that if you use RAW and a raw converter which does not attempt to apply lens aberration corrections that you can get the following sizes from the sensor:

  • 4016 x 3016 Pixels (12.11 MPixels) (4:3)
  • 4144 x 2768 Pixels (11.47 MPixels) (3:2)
  • 4368 x 2464 Pixels (10.76 MPixels) (16:9)
  • 3008 x 3008 Pixels (9.05 MPixels) (1:1)
It would seem that the sensor is not just a plain grid but is instead a series of grids.

Now I was familiar with how my G1 performed when using RAW and converters such as dcraw to do the conversion, I got 4016 x 3016 which is a wee bit more than the standard 4000 x 3000 pixels that you would otherwise get. Nice to be sure, but nothing to write home about.

The GH1 on the other hand gives the following which really does begin to make a difference... So when you choose aspect ratios such as 16:9 the camera actually uses different parts of the sensor, and gives you more pixels not just cropping down the 4016 x 3016 to a lower height to fit into 16:9

The picture below was taken with my Olympus OM 50mm lens and I changed the recording formats. I converted and then pasted each image into an overlay as below:
You can see clearly that the 4:3 records a greater height than anything and the 16:9 records a greater width. Looking in particular at the 16:9 compared to the 4:3 we see this

So the 16:9 is recording 352 more pixels (and importantly) by actually capturing a wider area of the image circle cast by the lens.

Is this significant?

well that depends on you. If you are the sort of person who would buy a 24mm lens because a 28mm isn't wide enough then this difference is nearly the same as that.

Also, most people considering cameras suggest that APS cameras are better than 4/3 cameras because the APS camera has a wider sensor thus capturing the image better and not squeezing those pixels into a smaller area (pixel density). So here we have a 4/3 camera which shoots a format which is a little larger than 4/3 and produces an image size that is more pixels wide than an APS-C camera like the Nikon D5000 (4288 x 2848 pixels) when its wide shots you're after. Even shooting at 3:2 format (that of the APS-C camera) the image obtained from the GH1 is 4144 x 2768 Pixels which is so close to the APS-C that you can see there is nothing in it.

Then of course there is the video and the fact that the GH2 would seem to be even more again.

No wonder I keep seeing more Panasonics out there when I'm traveling

1 comment:

Charles Maclauchlan said...

this is a surprise. I had thought that all of the wide or "panoramic" cameras just cropped top and bottom.