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DXO dissonance and review sites
#1
Right now there're a slew of 16 and 24mp sensor based cameras in the market, with more to follow, like D5200, D400 etc...

Basically they are all Sony sensors.

DXO has reviewed these sensors, and in general, the newer 24mp sensor is found to be better overall, and even in low light performance.

Review sites seem to be on the same page as well.

I find it hard to believe, because i have inspected images from these cameras (A65, D5100, A57, D3200) and found the 16mp images to be cleaner in low light...

I can see noise and grain even in ISO 100 images of 24mp sensors, ISO 400 definitely noisier, and 800 being very noisy. 16mp images also show noise, but 1600 ISO is relatively cleaner.

Don't know what's going on?

Dpreview recently gave same scores to both D800 as well as Mark III...???

sensors are getting better??
#2
DxO make their sub-scores on a specific test method. If you use a different method of evaluation, you will get different results.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.
#3
[quote name='nandadevieast' timestamp='1339330114' post='18821']

...

I find it hard to believe, because i have inspected images from these cameras (A65, D5100, A57, D3200) and found the 16mp images to be cleaner in low light...

I can see noise and grain even in ISO 100 images of 24mp sensors, ISO 400 definitely noisier, and 800 being very noisy. 16mp images also show noise, but 1600 ISO is relatively cleaner.

Don't know what's going on?

...

[/quote]



there is a review of the D3200 out at cnet.de that rate the image quality worst compared to the D3100 and basically is line with you observation.
#4
[quote name='nandadevieast' timestamp='1339330114' post='18821']

Right now there're a slew of 16 and 24mp sensor based cameras in the market, with more to follow, like D5200, D400 etc...

Basically they are all Sony sensors.

DXO has reviewed these sensors, and in general, the newer 24mp sensor is found to be better overall, and even in low light performance.

Review sites seem to be on the same page as well.

I find it hard to believe, because i have inspected images from these cameras (A65, D5100, A57, D3200) and found the 16mp images to be cleaner in low light...

I can see noise and grain even in ISO 100 images of 24mp sensors, ISO 400 definitely noisier, and 800 being very noisy. 16mp images also show noise, but 1600 ISO is relatively cleaner.

Don't know what's going on?

Dpreview recently gave same scores to both D800 as well as Mark III...???

sensors are getting better??

[/quote]



They are basically evaluating the quality based on the same print size.

This is similar to downsizing your 24mp images to 16mp and compare the result thereafter in your case.





#5
Isn't that a good way of doing it? They could of course do both IMO, for cropping images, it's more important to know the noise level at pixel ratio instead of at a certain print size with the whole image.
#6
[quote name='Klaus' timestamp='1339340997' post='18824']

They are basically evaluating the quality based on the same print size.

This is similar to downsizing your 24mp images to 16mp and compare the result thereafter in your case.

[/quote]



Are you sure about this? Does DXO say that they do it as per print sizes?

Then the review sites should be upfront about it...they should say that well, you can crop, but it will be noisier then...

They should also talk about pixel level noise, noise at 1:1...



Today i opened an old shot from a Canon IXUS brick...6 megapixel...you can see the definition of each and every leaf...
#7
They look at RAW files and measure noise from that RAW file, amongst others. Any camera that does more noise suppression in RAW will get a better score. All cameras do to some degree, but some do this more than others. Whehther that is something one would want in a RAW file, is debatable. However, lower noise in RAW means better scores....



Of course, sensors do improve with each new generation (even if they seem to stay the same <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='Big Grin' />), so that has an effect too.



Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
#8
[quote name='nandadevieast' timestamp='1339343591' post='18826']

Are you sure about this? Does DXO say that they do it as per print sizes?

[/quote]



Yes, I am sure about that. All dxomark scores are calculated at 8 MP. That includes Nikon D800 with 36 MP sensor .. and 90 MP MF cameras. The 24 MP sensor cameras will gain a lot more when when downsampled to 8 MP, then the 16 MP. That's why, even though the 16 MP sensor is better at pixel level, the 24 MP sensor scores just as well on dxomark
#9
Their analysis is done at a given output size (in their case, 8MP).

It makes much more sense to compare the IQ at a given output size which it what happens when you look at an image. Whether you use a 6 or 36MP camera, your final image will be printed (or displayed) on a given medium at a fixed size. At the pixel level, a 36MP sensor will give you more noise than a 6MP one (given similar technologies). However, the s/n ratio of the larger image, when downsized, will greatly improve.

A larger number of pixels (at equivalent technologies) is beneficial at low ISO because it gives you more details, while still giving you similar high ISO performance due to the averaging of neighboring pixels. You can see this trend pretty well when comparing graphs from the 16 and 24MP sony sensors you're talking about. Comparison between Nikon's D800 and D4 give you similar figures.







[quote name='nandadevieast' timestamp='1339330114' post='18821']

Right now there're a slew of 16 and 24mp sensor based cameras in the market, with more to follow, like D5200, D400 etc...

Basically they are all Sony sensors.

DXO has reviewed these sensors, and in general, the newer 24mp sensor is found to be better overall, and even in low light performance.

Review sites seem to be on the same page as well.

I find it hard to believe, because i have inspected images from these cameras (A65, D5100, A57, D3200) and found the 16mp images to be cleaner in low light...

I can see noise and grain even in ISO 100 images of 24mp sensors, ISO 400 definitely noisier, and 800 being very noisy. 16mp images also show noise, but 1600 ISO is relatively cleaner.

Don't know what's going on?

Dpreview recently gave same scores to both D800 as well as Mark III...???

sensors are getting better??

[/quote]
--Florent

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