Ideal resolution for a full frame Foveon sensor?

Started Mar 4, 2012 | Discussions thread
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DaSigmaGuy OP Forum Pro • Posts: 12,303
Re: Ideal resolution for a full frame Foveon sensor?

cptrios wrote:

DaSigmaGuy wrote:

The resolution of the SD1 sensor is 4800x3200, which works out to be exactly 200 photosites/per mm on both the x and y axis. 200 x 36mm = 7200. 200 x 24 = 4800. 7200x4800 = 34.56mp, or roughly 35mp rounded up. So the resolution of a full frame Foveon sensor with the same amount of photosite/mm as the SD1 sensor would be about 35mp.

Now, I know that a FF cut of the SD1 sensor would have its share of issues - noise, shadow banding, etc. And it would put more stress on lens corners than any sensor in history. But it would be ridiculously great for many things. Bear with me:

• Let's assume that the most common print size is 8x10. So, for the purposes of a 2:3 sensor, 8x12.

• Judging by my own playing with Foveon-produced files, I would say that with a good lens and good PP, it's more than possible to print an excellent 8x12 from a 1000x1500 (1.5MP) crop. Probably even smaller - but let's say that number's safe.

• Using DSG's calculations, one could therefore crop a good 8x12 from 4.3% of this theoretical FF sensor's total area. 20.8% of width and height.

Therefore, based on my rather clueless calculations of FoV (which I'm sure I'm doing incorrectly):

You could slap a Zeiss 21/2.8 Distagon on this camera, and, if you never planned on printing larger than 8x12, you effectively (ignoring DOF and perspective) would have a 21-120mm zoom. A Sigma 85/1.4 (provided you used the center, where sharpness is good enough) would give you an 85-410mm zoom. A good 200mm prime would get you as close as 850mm . A 28-300mm zoom (of which none are of course good enough for the purpose) would give you a whopping range of 28-1200m.

Like I said, I'm sure my calculations are off...but even so, the cropping power you'd have would be out of this world. You would, for example, get a nicely-detailed 8x8 of the Moon, where the Moon filled the entire frame, with a 300mm lens.

And, of course, uncropped with an excellent lens we'd be talking 7-foot prints that would hold up to close scrutiny, and probably 15-foot prints that'd be fine from a few feet away.

It does'nt work that way...You have to multiply the lens focal length by the crop factor (1.5x for the SD1M) to give you the FF equivalent focal length.

For example, the Zeiss 21mm will give you the same FOV as a 31.5mm lens would do on a FF camera. Cropping reduces resolution though so while the FOV gets less when you crop, sort of simulating having a greater focal length lens, resolution goes down which does not happen when you actually use a longer focal length lens. So cropping should only be used as a last resort, not all the time, and you would be far better off getting some longer lenses and stitching the resulting shots into panoramas to increase the FOV whilst giving you maximum image detail.

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