2008 -Salviano Junior
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The results below are from the 1st round.
If you want to do the 2nd round ( after improved workflow), please start here.
Jump to Conclusion.
Results of the 1st round:(in the same sequence of the questions)
|Wich one is the photo taken ...|
|on 26/ aug/2008 22:00 -3 GMT: The partial results below are taken before the right answers were revealed.|
on 30/ aug/2008 20:00 -3 GMT: The partial results below was taken after the answers were revealed (but I made possible doing the test before seeing the results, so I believe all people also voted before.
|Additional words about
the procedure and equipment:
For this experiment, I used brand new camera and lens acquired from legitimate, authorized and well reputed suppliers. The equipment seems not to be defective, so I can't list any problem with it. Same to the lighting set-up, tripod, cable release and whatever.
I taken seven shots in sequence with different apertures, but same EV. I processed all files with similar settings - including sharpening - as I said before - the only difference was regarding the fine-tuning Smart-Sharpen/Lens blur. It's important to remember that all RAW files needs to be processed before presentation.
Important - added on 30-aug: To the 2nd round I used O (zero) value of sharpening for RAW conversion and when pp editing an equal amount of sharpening for all photos)
The photo taken with f/22 was discarded for boht rounds - because of the average low quality, when compared with the others. It is confirmed with a MTF number of 43% less when compared to f/8. But...
Notwithstanding the carefully technique to shot the photos, it was very difficult to find plenty valid correlation betwen the most of the MTF numbers and photos not taken in a laboratory environment - at least in the case of this specific test. See the results above to confirm that. Only two of six apertures are corrected identified, and the large amount of errors are much more relevant.
Published also as a post on The Online Photographer (thanks to Mike Johnston)
are an objective measure of optical quality. The bigger the number,
the better the optical quality of the glass. But is hard—if not
impossible—to do exact measures of the impact of this optical
quality in "real" photos, even when using an accurate technique. (But
not scientific—a photographer don't need to be a scientist).
Salviano Junior - Rio de Janeiro - Brasil
|DNG download link - 1 zip file with the seven original DNG files taken for this experiment. Warning: huge 86.379 KB (Important: do the test before downloading)|
|JPG view/download for reference. Untouched file taken with f/8 (my default aperture)|
1. Although the image of the goblet is black and white, all the test photos taken display some levels of coloured patterns in this area. (moirée).
Below, a closer look of these details - JPEG croped and saved as 95 quality:
Close-up - Pentax SMC DA 35mm macro limited
2 - Tables of percentages relative to the best aperture:
3- Hmm... As I, do you also think that all apertures are plenty usable - even f/22? Ok, depends on the circumstance.4- When writting this webpage about MTF, I remembered of the other acronym named MTBF.
It's a industrial parameter meaning "Mean Time Between Failures",a measurement of reliability for electronic components (Computers, Electronics etc.)
I concluded that the added word mean is per se a failure... or not. You decide.
A big Thanx to the all participants!
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