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Author Topic: Sensor size v Lens size compromise - Your views  (Read 4575 times)

Jim Kasson

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Re: Read Noise and Practical Photography SNR
« Reply #40 on: June 06, 2017, 10:38:47 AM »

Even in a disaster scenario, with the D610 limited to an SNR of 1, the EM-1 would have an SNR of 1.33 - the difference wholly accounted for by the EM-1's lower read noise and still very, very far from 2x.  I would also like to point out that all formats are fast converging to the current read noise limit of just over 1e- per pixel in 'dark' ISOs (see FF cameras released over the last year or so), therefore it's unlikely we are going to see such big differences in disaster scenarios in the future.

Jack, are there MFT cameras available with DR-Pix technology or something similar?

Jim

Guillermo Luijk

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Re: Sensor size v Lens size compromise - Your views
« Reply #41 on: June 06, 2017, 11:47:09 AM »

Even in a disaster scenario, with the D610 limited to an SNR of 1, the EM-1 would have an SNR of 1.33 - the difference wholly accounted for by the EM-1's lower read noise and still very, very far from 2x.

The 2x factor appears when the compared cameras have the same photosites, as I already said. The whole demo was aimed at making the "FF is equivalent to M4/3 with two extra stops of exposure" false, as I already said too. In general the smaller sensor (or crop from the big one) will beat the larger sensor in SNR, as my cameras test and your example show.

Regards
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Jack Hogan

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Re: Sensor size v Lens size compromise - Your views
« Reply #42 on: June 06, 2017, 12:42:24 PM »

The 2x factor appears when the compared cameras have the same photosites, as I already said.

If you assume the exact same pixel (size and read noise), say that of the 7DII then at the lowest acceptable shadows by PDR's definition SNR is 4.4 and a 5DS would show 4.7, a ratio of 1.07.  In the disaster scenario with the 7DII at SNR =1, the 5DS would be at 1.25.

The whole demo was aimed at making the "FF is equivalent to M4/3 with two extra stops of exposure" false, as I already said too. In general the smaller sensor (or crop from the big one) will beat the larger sensor in SNR, as my cameras test and your example show.

Should we try it with more recent cameras, say EM-1II and a9?  The a9 is better, the ratio of the two SNRs of 0.96 at PDR and of 0.78 in the disaster scenario.

In my opinion it is misleading to say that a smaller format will automatically have higher (or 2x) SNR than a larger one.  That has virtually nothing to do with format size and all to do with the read noise (and other non-idealities) of the sensors and lenses involved.  I'll leave it at that.

Jack
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Jack Hogan

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Re: Read Noise and Practical Photography SNR
« Reply #43 on: June 06, 2017, 01:24:35 PM »

Jack, are there MFT cameras available with DR-Pix technology or something similar?

Assuming those steps are it, it looks like the latest generation does Jim.  From http://www.photonstophotos.net/Charts/RN_e.htm



Jack
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