Saturday 17 September 2011

The Great DSLR Dynamic Range Lie!

Dynamic range is a term used to talk about how well a camera is able to capture detail in an image from its darkest to its brightest parts.  Theory suggests that with big photosites in the sensor you should have greater latitude/dynamic range in an raw file than a camera with smaller photoshites.  If you have 12million photosites on a sensor twice the size of the other it would see fit that the photosites are twice as big and potentially be able to capture twice as much information in the highlights (not so much in the shadows so the theory goes).  But this does not seem to be the case.


So again lets reiterate the theory


With double the size of the sensor, you give your photosites a much greater size meaning you should be able to caputre much greater dynamic range.


I just tested it out on the D300 vs the D700 (both with 12mp but the D700 has double the size sensor = double the area = bigger photosites) yet it is almost impossible for me to notice any difference in the images produced by the two.

Don't be fooled into thinking that pixel density has anything to do with dynamic range, I suspect it is far more to do with sensor techology and photosite layout rather than number of pixels per area.





This here is a video that states the oposite to my discovery above



Thom Hogan also gives the Nikon D700 a 9 stop level of dynamic range
http://www.bythom.com/nikond700review.htm
"Dynamic Range





At the base ISO, easily nine stops of usable dynamic range are produced by the D700. Moreover, it has a Fujifilm S5 Pro-like ability to have a little latitude in exposure. I can usually bring back in a stop of highlights on raw files, when necessary, so I don't fear pushing my channel values a bit"

Here is a quote from Dpreview  http://www.dpreview.com/learn/?/key=Dynamic_Range

One of the reasons that digital SLRs have a larger dynamic range is that their sensors have larger pixels. All things equal (in particular fill factor, "bucket" depth, and exposure time), pixels with a larger exposed surface can collect more photons in the shadow areas than small pixels during the exposure time that is needed to prevent the bright pixels from overflowing.  




Here is another link for you

Check the DXO mark results  












Now if You want a look for yourselves or even make a video showing where I may have made a mistake please download dropbox 


To get the photos you will need the free file sharing thingy called Dropbox

You can get the link for that by clicking on this  http://db.tt/W88s4mP



Once you have got that then click on this to download the original raw files. (there are 6 in total each one is about 25mb in size)


https://www.dropbox.com/gallery/10504939/1/dynamic%20range%20photos?h=5889fb 












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2 comments:

  1. I would never think that dynamic range is contingent on the size of the sensor. Dynamic range is completely contingent on the processor and the algorithm used to control the pixels on the sensor. As far as I understand, and I an no engineer, is that the more times or passes the light coming into the lens and over the sensor the better the range you will have. to me that makes sense. If pass number one exposes the shadows, pass number two exposes the midtones and pass number three exposes the highlights then to me you would full dynamic range. To achieve this you would need a super processor or maybe even two of them and then you would be limited by shutter speed. To say you could achieve more passes at 1/100 vs 1/1000. As far as I understand the processor takes an average of the light once the sensor is exposed, much the same way evaluative or matrix metering does. I believe that is why all DSLR cameras are capable of exposure bracketing, to essentially achieve three passes of light over the sensor at different exposures of the same image.

    again, to re-iterate I would never think dynamic range has anything to do with the size of the sensor. ISO? Definitely.

    just my two cents

    Ross

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  2. ^ Completely worthless comment. No such thing as "passes" in a standard single shot exposure.

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