Cross platform equivalency

Started 8 months ago | Discussions thread
Great Bustard
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In reply to Rick Knepper, 8 months ago

Rick Knepper wrote:

FF > MF that is.

Yes this will concern a rumored Canon camera, not an actual one (at least for the moment).

I am pretty comfortable in my understanding that more MPs per given area results in more detail.

Let's say this rumored camera, casually referred to on this forum as the High Resolution Monster, has 51 MPs just like the Pentax 645Z.

Those same number of MPs will be laid out on .79x less area on Canon's FF sensor as opposed the Pentax sensor.

I have admitted in the past that I am fuzzy on cross platform equivalency but until now I have not been interested in anything but FF. The Pentax 645Z may change that.

Noise and DR aside, which set of 51 MPs will produce more detail, less detail or the same detail in the respective systems all other things being equal?

GB mentioned large pixel blur the other day so I am interested if that concept applies here in any way since the pixels on the Pentax sensor will be larger.

Anyone not familiar with the Pentax 645Z can catch up here:

http://www.dpreview.com/news/2014/04/15/hands-on-with-the-pentax-645z?utm_campaign=internal-link&utm_source=mainmenu&utm_medium=text&ref=mainmenu

The pros of the 645Z, $8499, 51 MPs. on a sensor larger than FF, weather sealed, 25 cross-type AF points, and wait for it.............. articulating LCD.

The cons: 3 fps.

Lenses for the system mostly look reasonably priced although you won't find any pity-fifty pricing. The MF>FF crop factor is .79 according to DPR.

http://www.bhphotovideo.com/bnh/controller/home?O=&sku=1045517&gclid=CMOVld_K5L0CFdBcMgodCCkAGA&is=REG&Q=&A=details

Here we are:

http://www.josephjamesphotography.com/equivalence/#lensvssensor

In short, the resolution as a function of sensor size and pixel count can be summed up as follows:

For a given lens sharpness, the difference in resolution (lw/ph) between two systems will be between the ratio of the sensor heights (enlargement ratio) and the ratio of picture height in pixels (linear pixel density). The sharper the lens, the closer the balance will be to the ratio of linear pixel density, the less sharp the lens, the closer the balance will be to the enlargement ratio.

More specifically, the lenses for a 51 MP FF DSLR with the same AA filter as the 645Z will have to be 1.3x sharper than the lenses used on the 645Z to resolve as well.

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