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Author Topic: Sony A900 and Canon 5D MKII Article and DxOmark SNR 18% results  (Read 2557 times)
amin
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« on: January 05, 2009, 09:29:06 AM »
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Regarding this article on LL:

Michael showed the "Screen" comparison for SNR 18%, whereas the more appropriate comparison would have been the "Print" comparison.  It makes little difference given that the megapixel count is close, but the "Print" results show less than a 3dB difference between the two cameras at any measured ISO.  According to Michael, a difference less than 3db ought to be visibly insignificant at any comparable ISO.  Looking at the attached figure, A900 manufacturer ISO 6400 is only 1/2 stop noisier than 5D II manufacturer ISO 6400.  Even this minor difference is partially explained by the difference in measured ISO (4706 for the A900 versus 3990 for the 5D II).  

Michael's states that "At ISO 800 and higher the Canon is visibly superior, especially in the noise department."  I don't discount his observation, but it doesn't jibe with the DxO data presented in the same article.
« Last Edit: January 05, 2009, 09:31:15 AM by amin » Logged

michael
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« Reply #1 on: January 05, 2009, 09:40:04 AM »
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When it comes to a conflict between numbers and the evidence of your eyes, go with your eyes.

Michael

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ErikKaffehr
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« Reply #2 on: January 05, 2009, 09:40:35 AM »
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Hi,

Just a couple of viewpoints:

1) The print size assumed in DxO tests is a pretty small one, around A4. They have chosen this so they could compare cameras having 8 MPixels and upwards. Not necessarily adequate comparison if you print A2s.

2) I don't care that much about small differences regarding noise. Although i wouldn't argue with DxO's way of measuring noise, it works the way that what you measure is not always what you see.

Digging to all information on DxO I would say that the 5DII seems to have about one stop advantage over the A900 in most regards at high ISO.

Best regards
Erik

Quote from: amin
Regarding this article on LL:

Michael showed the "Screen" comparison for SNR 18%, whereas the more appropriate comparison would have been the "Print" comparison.  It makes little difference given that the megapixel count is close, but the "Print" results show less than a 3dB difference between the two cameras at any measured ISO.  According to Michael, a difference less than 3db ought to be visibly insignificant at any comparable ISO.  Looking at the attached figure, A900 manufacturer ISO 6400 is only 1/2 stop noisier than 5D II manufacturer ISO 6400.  Even this minor difference is partially explained by the difference in measured ISO (4706 for the A900 versus 3990 for the 5D II).  

Michael's states that "At ISO 800 and higher the Canon is visibly superior, especially in the noise department."  I don't discount his observation, but it doesn't jibe with the DxO data presented in the same article.
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amin
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« Reply #3 on: January 05, 2009, 06:20:15 PM »
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Quote from: michael
When it comes to a conflict between numbers and the evidence of your eyes, go with your eyes.

Michael

As another person who enjoys testing cameras by comparing prints (and in my case, also pixel peeping), I agree with you with a small but significant caveat.  My eyes cannot tell me if what the manufacturer is calling ISO 6400 is really ISO 6400.  My eyes also can't tell me if what the lens is reporting as f/2.8 is really f/2.8, if the reported focal length of 35mm is really 35mm, or the reported shutter speed of 1/50s is really 1/50s.  If the DxOmark methods are sound, and I don't know one way or the other, then their data may have an important role in challenging the assumptions on which we base the evidence of our eyes.
« Last Edit: January 05, 2009, 06:20:38 PM by amin » Logged

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