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Sony Alpha 900 vs. 67 analogue, round 2 - The issues with the red flowers

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Article Index
Sony Alpha 900 vs. 67 analogue, round 2
Dynamic range
The issues with the red flowers
Good comments from Dominique Ventzke
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The issues with the red flowers

Note: This issue was pointed out to me by Dominique, who also referred to this article

Another crop from the same image shows a red flower. This flower has some issues both in Analogue and digital. The digital image is heavily pixelated. The main reason for this is probably that the sensor uses a so called "Bayer matrix". The Bayer matrix has red, green and blue pixels laid out this way:


Only one fourth of the pixels are red, so for the read color the 24 MP Alpha 900 turns into a 6 MPixel camera. Essentially all DSLRs and MFDBs use the "bayer matrix" solution, with the "Foveon sensor" used in several Sigma cameras being the sole exception. Note within the red frame that the small red flower is resolved on both Ektar scans, but is essentially almost invisible on the Alpha 900 image.

Sony Alpha 900 (upsized) Ektar 100, High End Scan at 6096PPI
Ektar 100, Dimage Scan Multi Pro at 3200, upsized

It is possible to extract more "red flower detail" from the High End scan, Dominique Ventzke, who made the scan posted the image below made from the same scan (click on the image for actual pixels) :


Another image...

In the image with the red flowers I have some sensor shake caused by in camera image stabilization. I made another shot comparing the Alpha 900 and Ektar. The Ekatr image was in this case not scanned on a drum scanner but we can still compare with my MDSMP 3200 PPI sxan.


Based on the above samples I would draw the conclusions:


  • It seems that  a well executed Ektar 67 image scanned on a CCD film scanner will have similar detail to a well executed 24.5 MPixel picture by a full frame DSLR.
  • A drum scan will not necessarily extract more detail but the resulting image will be smoother.
  • In either case the resulting image can be varied a lot. With the scanner much depends on the operator.
  • It is not clearly evident that film has wider dynamic range than digital, but behaves very differently.
  • It is very clear that expert drum scanning at high resolution gives superior results to "amateur CCD" scans.
  • In the red flowers we see some limitations in handling very fine single color detail, due to the "Bayer matrix".


Finally, postprocessing matters a lot. The results depend much on sharpening, noise reduction and so on.


To me it seems that 67 film needs to be drum scanned to surpass 24 MP digital full frame.



Last Updated on Tuesday, 29 November 2011 00:33  


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