TheNorthern
First Officer
Flight distance : 419134 ft
Norway
Offline
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Copy paste from a Facebook discussion, permission given to copy it:
John Phillips: From someone who works in TV for the past 40 years... What this guy is claiming is totally bogus. 1080 and 4K are exactly the same resolution. 4K is just 4x 1080 pictures joined together to give you more real estate. The only real benefit of 4K is in editing you have a lot more latitude to digitally crop a piece of the picture and still have 1080 resolution. That's it.
Where this guy is incorrect is that the resolution changes depending on what mode you're in. In fact is, in either mode you still have either 4K (3840x2160) or HD (1920x1080) resolution being recorded. Because they're all fixed focal length lenses, what changes is the processing that zooms them in to change the field of view. It does not change the recorded resolution but like any digital zooming it will slightly degrade the actual picture quality.
Resolution in television was originally measured in scan lines back in the days of SD but now it's measured in pixel lines in digital. So no matter what mode you're in, you're still getting 2160 (4k) or 1080 (HD) lines of resolution.
When he talks about "pixel skipping," what he's really referring to is compression, not changes in resolution. Video is compressed to save data in the recording. More compression = poorer picture.
As for his claim of "line skipping," I'd like to see some proof of his claim that they're skipping scan lines on the sensor. If this were true, it would mean that you're not getting a true HD image out of the sensor and that makes absolutely no sense. If you eliminate half the lines of resolution you're reducing the image down to slightly higher than SD resolution. That would be extremely noticeable and most people would find it unacceptable in any conditions.
As for his tests, If this guy was doing a legitimate test of the images he would have had a serious set of SMPTE camera charts to show both resolution and coloremetry. The fact that he printed out a chart and it's not correctly scaled tells me he has no clue what he's talking about. Firstly what he used was not a legitimate SMPTE resolution chart. The link below shows what legitimate SMPTE (Society of Motion Picture and Television Engineers) resolution charts look like. They start at about $2 grand each. Clearly not something you print off of the internet. Besides which, there is no home printer capable of printing the kind of resolution required for a real resolution chart to actually work. http://dsclabs.com/test-charts/resolution-focus-test-charts/
The last thing that blew all credibility for me of his claims is that he was using some kind of pot with a piece of the field turf from the super bowl in it as a reference for focus. What a joke. This is no legitimate test. Again there are proper, calibrated focusing charts available to do this properly.
So in short, I think you can distill the changes in the images down to two things... video compression and processing and likely quality of the glass in front of the sensor. Let's face it, folks, you're not getting the same quality glass in a $1200 drone as you would in a $150k UHD television camera lens.
FYI, this is what a $150k television camera lens looks like... and there's a reason why they cost $150k: https://www.usa.canon.com/internet/portal/us/home/products/details/lenses/broadcast/4k-uhd-field-box-lenses/uhd-digisuper-122
The only one thing he said about the drones that made any sense is that they all look pretty good. |
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