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MF Digital, myths or facts? - Experts's comments

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Article Index
MF Digital, myths or facts?
Collecting more photons
Comparing the top of the line MF back with the top of the line DSLR
Is Capture One better on IQ180 files?
A larger format is less demanding of the lens
The Really Right Stuff
OLP (AA) filtering
The 16 bit issue, truth or myth?
Do MFD have better DR?
MFDBs have better color, truth or myth?
Summary and conclusions
Are large pixels better?
Read also
Experts's comments
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Experts's comments

Doug Peterson, guru of Medium Format at Digital Transitions responded by saying:

"It is often too easy to analyze specific components of a system and lose the forest for the trees. No manufacturer selects any component based on it's individual spec, but rather how it will contribute to the image quality chain, speed, size, weight, power drain, and production cost of the entire system. 

For instance the selection of a specific A/D convertor is not made based on a label of "8 bit" or "16 bit" but rather for how well, how quickly, and how reliably it converts from analog to digital and how good the resulting digital file is. Marketing it as a "16-bit product" is short hand for referring to great tonality and elasticity-under-adjustment that the resulting raw files have.

Another component in this image quality chain is the software. The team all works together: Team Phase One engineer that lead the team that designed the Dalsa IQ180 sensor, the Team P1 engineer who lead the team that selected the a/d convertor and other electronics (including the very well performing dark-frame calibration hardware), the Team P1 engineer who is head of the team that handles color rendering and profiling, and the Team P1 engineers who work on the underlying algorithms of Capture One to pull the most detail with the least noise from the raw file. These team members live and breath image quality, and work together - their decisions for any given component in the image quality chain are deeply guided by this team work. 

For instance the dark frame calibration technology is designed with the sensor, a/d convertor, and raw processing algorithms in mind. This will be most glaringly obvious when opening a long exposure in both Capture One (which takes advantage of the dark frame data) and ACR (which does not) but the difference is present in all images. 

There are many, many aspects of image quality which cannot be fully wrapped into a single numerical value. Dynamic range for instance is very poorly represented by a simple statement of "XX stops." If a detail in the shadows can be seen, but is rendered in an ugly way - say for instance with blob-like (low frequency) color noise, or with clumpy or rectangular noise artifacts then it is not photographically useful. If a highlight can be recovered but it has odd stepping patterns or poor color accuracy it is of minimal photographic use. In this regard there is no single answer for "how many stops of dynamic range does this camera have" when the motivation for the question is photographic and not scientific - no matter what manufacturers or testing agencies like dXo would have you believe.

Noise, likewise, cannot be quantified entirely in one numerical value. Nor can it be measured in isolation from the effect of the raw processor. Open an ISO3200 file from an IQ160 in Capture One 6 and Capture One 7 (as we have illustrated on our Phase One Facebook page) and you will find a drastically more photographically useful image in Capture One 7. There is less noise, it is more easily removed without compromising detail, and the noise that is present is "pretty" (gaussian in nature, evenly distributed, without signs of clumping or rectangular blockiness). Notably the improvement in processing for Phase/Leaf files in C1v7 vs C1v6 is greater than the (still notable) improvement for dSLR files. This is because the software team can consult directly with the guys who make the back (and literally design the sensor) and have taken enormous effort at making the end-result of the image quality chain as good as possible.

When analyzing camera systems it makes sense to analyze the entire chain as a whole. I genuinely believe the IQ180 sensor, when coupled with Capture One and a good set of lenses, is the best system on the market for the purpose of producing raw files for photographic use (with the standard caveats that other cameras will exceed it for longer exposures and very high ISOs).

Tim Parkin of On Landscape sent this comment, mostly regarding color:

Hi Erik, Just taken a look at the article and the section on colour probably needs something explaining that colour accuracy with a colourchecker card is far from the main concern in terms of getting accurate colour. The biggest issue is metameric failure of the dyes used in the bayer array. I've done some analysis of this and looked into the visual quality of the cameras in the big camera comparison (feel free to link to the images directly if you like)

Here's the article talking about colour

In my opinion the quality of MFDB's varies hugely and is something I'll be testing more closely in the future. In our Big Camera Comparison I would say that we have a split from worst to best in the DSLR side with Canon generally pretty poor and Sony typically very good. With MFDBs the split was with the P45 being atrocious and the IQ180 being very nice indeed. However the best of all was the Sony A900 with the IQ180 and D800 close behind.. I wouldn't touch a P45 with a barge pole though (at least for landscape). Tim

Last Updated on Thursday, 13 December 2012 11:56  


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