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12-01-2010, 06:14 PM   #1
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Sensor difference due to optics in front of chip

There has been much discussion of the K5 sensor and how good it is.

I wonder if Pentax has different anti-alias filter and the light-collecting color filter above each electronic well on the Sony electronics. Seems I remember Pentax patents about color filters etc. Is this the reason cameras with the same sensor have different output?

RON C

12-01-2010, 06:39 PM   #2
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only one of the reasons
12-01-2010, 07:23 PM   #3
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How much of the difference is not sensor related?

RON C
12-04-2010, 02:14 PM   #4
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QuoteOriginally posted by rechmbrs Quote
Is this the reason cameras with the same sensor have different output?
Why do you ask?

The K-5 has no "AA filter" issue, if you are alluding to this past non-topic.

In general, RAW data isn't as raw as it may appear. Manufacturers massage the data from the sensor before it gets written to the card, this may even include noise reduction, so this processing is part of the reason why one and the same sensor may produce different images in different cameras.

12-04-2010, 03:26 PM   #5
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I'm aware that some processing is performed on the RAW data but no one ever mentions the micro-lenses which I was told were designed by the camera maker using Sony chips not the sensor maker. Source was a Nikon engineer. Have asked Pentax with no response.

RON C
12-04-2010, 05:56 PM   #6
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QuoteOriginally posted by rechmbrs Quote
There has been much discussion of the K5 sensor and how good it is.

I wonder if Pentax has different anti-alias filter and the light-collecting color filter above each electronic well on the Sony electronics. Seems I remember Pentax patents about color filters etc. Is this the reason cameras with the same sensor have different output?

RON C
The AA filters are all very similiar. Their thickness may vary slightly which means they require a bit different amounts of capture sharpening. Their color effect is probably very similiar esp. if everybody should really use lithium niobate.

The CFA filters vary (I'm not sure they are part of the microlens assembly). DxO-Mark has a page on the color transmission coffecients of the CAF filter. Pentax and Nikon seem to be similiar, Canon has a bit broader (read worse) red response.

The microlens assembly sometimes comes from the sensor manufacturer, sometimes from the camera maker. Pentax uses/used sensors from Samsung and Kodak which sold the sensor and microlens assembly as a single package.

For Sony, I'm not sure. You probably can buy it with or without the microlens assembly. It actually makes little sense if the camera maker designs it because it must be fine-tuned to the sensel architecture and manufacturing process. Sometimes, camera makers request a specification detail like Leica did for the M9. But AFAIK, Kodak still produced it.

Anyway, the microlens assembly in the sensor used by the K-5 is attached onto the CMOS layer and is part of the ceramic chip package you obtain from Sony.

And then there is an IR filter which does alter the color characteristic and sensibility too.
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