Supersample sensor then crop to Super16 @ 1080P?

[sumitagarwal]

Here's a thought since the GH1 (and especially the non-multi-aspect sensor in the GF1) is between Super35 and Super16 frame sizes: with a fast enough SD card would it be practical to read off the full sensor size at HIGHER than 1920x1080 and then post crop to 1920x1080 to eliminate the vignetting and distortion that often comes from using 16mm or 1" lenses on m4/3?

Might open up a lot of great and inexpensive lens possibilities!

 

[Nitsuj]

From http://www.dvxuser.com/V6/showthread.php?t=163339&page=54

QUOTE=Steve Castle;1617775]Wanted to comment on this, from the other *now closed* thread. I apologize if its seems off-topic...




The discrepancies between the two sources is that fourthirds-user.com uses 18x13.5mm while Bjørn uses 17.3x13mm for the 4:3 size. They are both correct. 18x13.5mm is the 4/3rds sensor's nominal size, 17.3x13mm is the effective pixel size. So you/Bjørn are right, the 16:9 is 18.8 x 10.6mm.

Assuming the diagram from Panasonic is to scale we can calculate the actual size of the GH-1 sensor:
Source: http://panasonic.jp/dc/gh1/photo_function.html
Source D90, T1i sensor size: http://www.neutralday.com/canon-eos-rebel-t1i-500d-vs-nikon-d90-prosumer-battle/

Assuming the 4:3 is 17.3x13mm, we can measure the pixels of the grey-area which represents the size of the GH-1 sensor measures to 20.2 x 15.1mm, and is a 4:3 sensor.

Comparison:

Nominal sensor size:
Canon 5D Mark II: 36 x 24mm (3:2 sensor diag. dist. 43.2mm) 1.0
Nikon D90: 23.6 x 15.8mm (3:2 sensor diag. dist. 28.4mm) 1.5 crop
Canon T1i: 22.3 x 14.3mm (3:2 sensor diag. dist. 26.5mm) 1.6 crop
Panasonic GH1: 20.2 x 15.1mm (4:3 sensor diag. dist. 25.4mm) 1.7 crop

However, the entire GH-1 sensor isn't usable, and the D90 and Canon T1i are 3:2 sensors, hence will need to be cropped to make 4:3 or 16:9. Comparing the the sensor to actual effective usable area we will have:

3:2:
Canon 5D Mark II: 36 x 24mm (diag. dist. 43.2mm) 1.0
Nikon D90: 23.6 x 15.8mm (diag. dist. 28.4mm) 1.5 crop
Canon T1i: 22.3 x 14.3mm (diag. dist. 26.5mm) 1.6 crop
Panasonic GH1: 17.9 x 11.9mm (diag. dist. 21.5mm 2.0 crop

16:9:
Canon 5D Mark II: 36 x 20.2mm (diag. dist. 41mm) 1.0
Nikon D90: 23.6 x 13.2mm (diag. dist. 27mm) 1.51 crop
Canon T1i: 22.3 x 12.6mm (diag. dist. 25.6mm) 1.6 crop
Panasonic GH1: 18.8 x 10.6mm (diag. dist. 21.5mm) 1.9 crop[/QUOTE]

 

[sumitagarwal]

My assumption on the width of the GH1 sensor in 16:9 would actually be derived from the 16:9 stills resolution, which is 4352, versus a width in 4:3 of 4000. I may be wrong, but I'm assuming that 16:9 simply uses the existing 4000 4:3 pixels plus some.

But more importantly, I think we should stop comparing sensor/active area diagonals and instead compare only active area widths. The reason for this is that for the vast majority of digital cinema creators, 16:9 is the absolute most square ratio they will be interested in finishing in, with many wanting to finish at 1.85:1 or much much wider. Thus when comparing 'crop factors', it is really only the image width that matters. When viewed this way, the GH1 has a significant leg up on the GF1, and the GH1 also comes within striking distance of the projection width of academy ratio 35mm film.

 

[Barry_Green]

Yes, the GH1 uses the 4000 4:3 pixels, plus some. The sensor is wider than the 4:3 image area. It's about 19mm wide.

Comparing width, you are correct -- it is very nearly the same size as 35mm cinema film.

 

[sumitagarwal]

Here we go, lens crop factors based on width, with academy projection width () as "1x". Anamorphic formats are ignored here as in those cases it is important to consider the sensor/frame height in addition to frame width.

16mm film: 10.3mm (2.1x)
Super 16 film: 12.5mm (1.75x)
Panasonic GF1: 17.3mm (1.3x)
Panasonic GH1: 18.8mm (1.2x)
Academy 35mm: 22.0mm (1.0x)
Red One: 22.1mm (1.0x)
Canon 7D/550D: 22.3mm (1.0x)
Super 35: 24.9mm (0.9x)
Canon 1D: 27.9mm (0.8x)
Canon 5D: 36mm (0.6x)
VistaVision: 38.0mm (0.6x)
70mm: 65mm (0.3x)
IMAX: 70mm (0.3x)

For the record, two of my very favorite movies to watch on Blu-ray were shot on Super 16: Monsoon Wedding, and The Hurt Locker. Also, while I set Academy 35mm as 1.0x here, I can easily see the argument for setting Super 35 as the 1.0x standard instead.