CCD Binning in Camera's

[Vladimir Steblina]

I have an astronomical CCD camera.  Since the early 1990's the astronomy CCD camera's have offered the option of on-chip binning.  Now this gives a lower file size and much greater sensitivity than an unbinned chip.

So why don't DSLR camera have binning as an option??  

Here is a technical discussion about binning:  http://www.ccd.com/ccd103.html.

In a full-frame camera it would be a huge advantage.  

The astronomical camera's also had flat-fielding.  Where you basically take a out-of-focus white flat picture.  This shows up all the dust on the chip.  So then subtract the flat from the picture and all your dust is magically gone!!  Sure beats screwing around in Lightroom or photoshop.  

Here is a very brief discussion of flat-fielding: http://en.wikipedia.org/wiki/Flat-field_correction

Any comments on why DSLR's do not have flat-fielding or binning??

Thanks....

Vladimir 

[fdisilvestro]

There are some cameras and digital backs that do perform binning on chip. Examples of this are the Phase One MFDB with the mode "Sensor +"
Even some consumer point and shot used this, like the Nikon Coolpix S710 (only at extreme high ISO, which produced mediocre images anyway)

I may be wrong, but I think that binning is not very common in DSLRs because it could only be implemented in CCDs, and most of the DSLRs are CMOS. Another issue is that you get 1/4 of the orginal pixel count (since most cameras use a bayer filter), so it makes sense only in a high pixel count camera / back only. (For example, a Phase One P65+ will give you a 15 MPixel image in Sensor + mode)

About "flat fielding" or dust elimination, I know that Nikon DSLRs have a function for that, provided you use the Capture NX (NX2) Raw converter. The limitation is that the "dust reference photo" has to be taken very close in time with the image you want to clean. Maybe dust in DSLR could change quickly (like every time you change lenses)

[feppe]

It can be used in CMOS: the recently announced Olympus E-P3/E-PM1/E-PL3 Micro Four Thirds cameras have binning in video only, and the CMOS sensor is designed by Oly, manufactured by Panasonic.

I believe the reason for lack of binning in small sensor cameras is that the MP count doesn't really support it until perhaps 30+ MP. Then again, since most people shoot for web, so vast majority of shooters would benefit from binning in stills. Perhaps marketing people haven't figured out how to sell a DSLR which has a low-res binned picture option, and/or it has been deemed too expensive to R&D and/or implement.

[Vladimir Steblina]

Actually, my astronomy camera is about one megapixel in 1x1.  It really helps in focusing and the sensitivity goes way up!!

In a full frame camera, binning would be a real feature particularly under low light situations and like you mention in smaller file size particularly for web publishing.

It should be fairly cheap to implement, on my astro camera's I just bin in the software.  If you guys know any astronomy folks with a astro camera you should ask them to show you flat-fielding and binning.

The advantages particularly for large chips become obvious.

[fdisilvestro]

You could do those functions in software with an application like IRIS , but I don't know if binning in software will give you the same results as hardware (in-chip) binning.

[deejjjaaaa]

It can be used in CMOS

certainly, Foveon CMOS has binning since it was born, close to 10 years ago, http://www.foveon.com/article.php?a=71

[Vladimir Steblina]

I just stumbled on to this web site.  Here is some interesting information on binning from Thom Hogan's web site:  http://bythom.com/  It is towards the tail end of his July 13th post.

Here is what he had to say about binning and Nikon:

From Thom Hogan

Now for the part that, I'm guessing, could be Nikon's surprise in August: binning. Binning isn't new. The D1 was a 10.4mp sensor that was permanently binned (four underlying photosites to one pixel). Nikon has played with binning since then, too, with the oddly binned D1x (two side-by-side photosites to one pixel). The answer to the "why 24mp question" suddenly becomes simple if you add binning to the mix: you potentially get a D400h and D400x all in one package. I do know that Nikon and Sony have been working on binning recently. That would make some sense for both stills and video and could lead to a jack-of-all-trades DX body that excels at everything: low noise, high resolution, video without artifacting, etc. And it would explain pursuing 24mp in DX and 36mp in FX.

But I'm only guessing at the binning thing. Without binning, and especially without BSI, we just have more pixels which means more data and power lines cluttering the sensor, meaning less light efficiency. Thus, even with the normal expected gains of a new generation of sensors, 24mp wouldn't really get us much further than the 16mp DX capabilities we already have, if any. Plus 24mp by itself really is pushing the full recording of diffraction into most image data.

End Thom Hogan..

Well, if this comes to pass it means that my next camera will be a Nikon and not a Canon.  Now if Nikon would offer flat-fielding I would have a great landscape AND astronomical camera!!

[PierreVandevenne]

You could do those functions in software with an application like IRIS , but I don't know if binning in software will give you the same results as hardware (in-chip) binning.

It's different. The main advantage on hardware on-chip CCD binning (for example 2x2) is that you add read noise only once as opposed to 4 times when the binning is done in software. Not sure how this works for CMOS sensors though.