Some info on the 24 MP Nikon - from a Sony engineer

Started Oct 29, 2008 | Discussions thread
bobn2 Forum Pro • Posts: 69,179
Re: Two inconsistencies...

Haplothedog wrote:

bobn2 wrote:

Iliah Borg wrote:

A good reason for Nikon not to use the A900 sensor in a flagship
model is that it has become better at designing sensors than Sony (or
Canon, for that matter).

Interesting how you manage to have two assumptions in one sentence

Yes, but there is some evidence to back the assumptions up. If you
have counter evidence...
Of course, it could be that Sony and Canon are better at designing
sensors but have decided for some reason not to release their better

Bob, you keep on saying that on DPR, but if we look at Roger N.
Clark. ( comprehensive work on Digital Camera
Sensor Performance, it appears that (if I am not mistaken, any reader
should visit clarkvision for details), comparing Nikon D3 and Canon

  • 1D III full well capacity is better than D3, even with smaller

pixel pitch

Yes, but you are comparing the 1DIII FWC at 100ISO with the D3 at 200ISO. The D3 gathers more photoelectrons per unit area than the 1DIII at 200ISO, and retains that advantage all the way up. It also has a big ISO 200 FWC advantage (65,600 plays 35,200, assuming that ISO 200 is simply ISO 100 with twice the read chain gain) at 200ISO. It's not as good at 100ISO. This is a design decision. restrict the cell capacitance, you get a lower FWC which translates to a higher conversion gain.

  • 1D III Signal-to-Noise Ratio is better than D3, even with smaller

pixel pitch

Only at 100ISO. If we define SNR as FWC/read noise (which is one sensible measure) then at 200, the 1DIII gets 35200/12.2 = 2869 = 11.5 stops whereas the d3 gets 65600/17.6 = 3727 = 11.9 stops. At 1600 we get 4400/4.2 = 1048 = 10 stops for the 1DIII and 8200/4.9 =1673 = 10.7 stops for the D3. Then, of course, the D3 has 50% more sensor area, which compounds the advantage. This triangulates with the real test results showing the D3 to have a clear advantage at high ISO's. The 1DIII has a very slight advantage in the 'best possible' from the camera. at 100ISO, it gets 70200/24.4 = 2877 = 11.5 stops against the D3's best at 200ISO. However, since the D3 has the advantage that its sensor is 1.5 times larger, it beats the 1DIII comfortably. It's not so much better off against the 1DsIII, where it loses the advantage. Overall, given the D3's better sensor efficiency and the 1DsIII's better read chain, the result seems to be a toss up, depending on sample variation as much as anything.

  • 1D III Read Noise is better than D3

Normalised to base ISO (100 plays 200) the D3 is actually better.

  • 1D III Dynamic Range is better than D3

As shown above, only at 100 ISO and then very marginally.

  • D3 Low Light Sensitivity Factor (high iso shadow perf) is better

than 1DIII

As shown above

  • D3 apparent IQ is better than 1DIII, mainly due to larger pixels.

I'm not sure of the value of this measure, but in any case, it's due to more pixels AND a larger sensor.

Mr Clark also proposes another view of sensors, using megapixels *
pixel pitch and so we have :
1. Sony A900
2. Canon 1Ds Mark III & Canon 5D Mark II
4. Nikon D3
5. Canon 1D Mark III

That takes no account of the actual quality of the sensor as a device for converting light to electric signals.

Maybe Nikon better designing is not that evident ?

Completely evident on those figures, if you read them better. As i said, Nikon has the lead in sensor design. Canon is still clearly better at read chain design. Put the two together, and it would be quite a camera. Since i mentioned it, using the d3 sensor with the 1DIII read chain you'd get

65600/12.2 = 5377 = 12.4 stops at 200ISO and 8200/4.2 = 1952 = 10.9 stops at 1600 ISO. That's half a stop advantage over the D3 at 200, alas only 0.2 stops at 1600.

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