BSI vs CMOS in low light photography

Started Sep 10, 2015 | Discussions
erotavlas Regular Member • Posts: 216
BSI vs CMOS in low light photography

In light of Sony's introduction of full frame BSI sensor.  Is there any real world advantage to using a BSI sensor for astro work?  Are there any disadvantages to using BSI compared with CMOS?

What about on smaller sensor like Samsung APSC sensors?

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Astrozoid
Astrozoid Contributing Member • Posts: 511
Re: BSI vs CMOS in low light photography

erotavlas wrote:

In light of Sony's introduction of full frame BSI sensor. Is there any real world advantage to using a BSI sensor for astro work? Are there any disadvantages to using BSI compared with CMOS?

What about on smaller sensor like Samsung APSC sensors?

BSI sensors usually have greater quantum efficiency, so you get a higher signal-to-noise ratio and that is a good thing.

The bad thing is that it's a Sony sensor, and they are using lossy compression on the raw files, and that is not a good thing:

http://www.dpreview.com/articles/2834066212/the-raw-and-the-cooked-pulling-apart-sony-raw-compression

The other consideration for astronomy is that sometimes you have to jump through hoops to get correct flat fielding: you need superflats to deal with fringing:

https://www.astro.uni-bonn.de/theli/gui/aboutsuperflatting.html

Jerry

Trollmannx Senior Member • Posts: 4,456
Re: BSI vs CMOS in low light photography

Astrozoid wrote:

erotavlas wrote:

In light of Sony's introduction of full frame BSI sensor. Is there any real world advantage to using a BSI sensor for astro work? Are there any disadvantages to using BSI compared with CMOS?

The back side illuminated sensor is a CMOS sensor turned backwards. So BSI = CMOS.

What about on smaller sensor like Samsung APSC sensors?

BSI sensors usually have greater quantum efficiency, so you get a higher signal-to-noise ratio and that is a good thing.

The bad thing is that it's a Sony sensor, and they are using lossy compression on the raw files, and that is not a good thing:

http://www.dpreview.com/articles/2834066212/the-raw-and-the-cooked-pulling-apart-sony-raw-compression

The other consideration for astronomy is that sometimes you have to jump through hoops to get correct flat fielding: you need superflats to deal with fringing:

The lossy compression is actually not a big deal (have to search long and hard to find visible real life compression artefacts). To me the bad news is heavy spatial filtering in bulb mode leaving the Sony user with rather unsharp images compared to unfiltered images.

Have posted examples in this forum.

https://www.astro.uni-bonn.de/theli/gui/aboutsuperflatting.html

Jerry

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