Comments on: Sensor quality: SLRs erode medium-format lead
DxO Labs' latest image sensor tests show that medium-format digital camera sensors don't hold a huge lead over top SLRs.
DxO Labs' latest image sensor tests show that medium-format digital camera sensors don't hold a huge lead over top SLRs.
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It's hard to beat 20 square inches of film, but it looks like that day is coming.
With high pixel count (even full frame) DSLRs, using the highest f-stops cause a reduction in the image resolution regardless of the sensor. On my 1ds iii, this diffraction limit is around f9, and it's based on the size of the pixel. Larger pixels (e.g. in a medium format back) mean higher f-stops. Before the physics majors get you with this inherent limitation, higher f-stops also mean a greatly increased sensitivity to flaws in the lens. Bigger lenses, bigger sensors, more glass involved in the picture, ...
(Great discussion of this: http://www.luminous-landscape.com/essays/Equivalent-Lenses.shtml, see Nathan M's comments.)
So, yes, marvel at the incredible depth and low-noise characteristics of the eensy-teensy pixels of the 1ds iii and d3x. But when you want to slam the iris down to f16 to maximize the depth of field, all those extra pixels are just sitting there laughing at you.
p.s. There's some "unobtanium" Flash Gordon stuff that we may get any decade now. It's a "negative index material," that could help fix this diffraction limitation. http://physicsworld.com/cws/article/print/19415
Now this new argument, given the research done by DxO, is quite plausible. Given that such big companies are behind the push, Nikon and Canon; the DSLR superiority over Full frame digital cameras is not so far fetched. Imagine; $8,000 DSLR delivering the same performance as a $25,000 Hasselblad?
By the way, the medium-format cameras all have on-chip noise reduction, which processes the raw data before writing the file that DXOMark evaluates. This makes the medium-format cameras appear to have less noise, simply because they have already run a noise-reduction algorithm.
Before putting too much stock in the new DXOMark tests, read this article from The Luminous Landscape:
http://www.luminous-landscape.com/essays/eyes-vs-numbers.shtml
The main point he makes is that the DXOMark test doesn't factor in camera resolution. This means that while the Canon and Nikon cameras may score as well on DXOMark test, the large-format cameras have nearly twice the resolution, making them better for professional-level photography or making large prints.
- by xcopy February 11, 2009 5:09 PM PST
- DXO's "findings", based on extremely flawed tests, need to be taken with a grain of salt. About a 50lb. bag should do it, but get an extra bag just in case...
- Like this Reply to this comment
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(8 Comments)I'm sure non-photographers, the "snap shooters" and the wannabes that discovered photography in the last couple of years will will believe this. Ignorance is bliss as they say. In reality the digital game is no different from the film game; bigger is better for image quality.
As good as Nikon's new D3x is (and it may be superior to Canon's best), it is not a match for medium format.