Björn Benckert
Well-known member
Wrote this in some Facebook thread where they discussed the same thing and all the BM camera owners where so happy that their pocket cameras shooting 2k actually is better or atleast as good as any other camera. 
Copy pasted from there:
Björn Benckert Saw all of part two now. This is so much fud that I dont know where to start. I could pick any segment in that clip and explain why he is wrong in more ways than one. Sorry.
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Björn Benckert
Björn Benckert So lets start with the easy bits:
Why does alexa 65 look better than the XT on closeup, grain halation and so on on pretty much every test done?... Sure, you can say different sized sensor but except for that. smaller noise better hard contrast edges etc. The camera has the exact same sensor tech as the XT and the Amira and the mini the only thing differ is the pixel count and sensor size. Same pixels but more of them... image looks better in all the different zoom in tests and also in the zoom out tests and also in the noise test, and yes pretty much in every little node tree this guy shows the XL looks better than the XT....
Now alexa 65 is a (i dont remember the exact numbers but it´s about) 6.5k something c-mos camera so in other words it resolve 1/3 to 1/4 of that which is about 2.5k so when looking at the alexa XL in this 4k crop in demo what do you actually see? Well you see at best lets say 3k but it´s really not better than 2.5k upscaled to 4k. If you took a higher resolving camera like a Phase One or such and shot a 18k image and placed it into a scene with a alexa XL in a native XL sized timeline... The phase one would stand out as a razor blade.
So simply this guy is sitting looking at cameras that resolve about 3k at best and say he can not see any difference between them, or little difference between them. Then we sit and look at the same test on a heavily compressed internet feed and say we also do not see any difference at these cameras shooting something like 2k when watching them in 4k....
Also he points at film and calls it 35mm film... he does not state what ASA. on film ASA is very determine to resolving resolution. So comparing film and saying it looks like this is kind of like taking a digital camera shoot a picture and say this is what digital images looks like... does not matter if the image is shot with a iPhone or a Phase one or Alexa XT.... it´s reference for digital camera, thats how those looks. Simply the silver particles on celluloid films vary in size for different ASA. So does the resolution. Another thing looking at film as a still frame is not fare. Film vary the layout of the silver flakes from one frame to another so that actually gives the viewer more info about the scene when watching a clip than just a still frame. In other words film played has a different resolution than a still frame...
Noise, noise is info even if it´s unwanted info it´s info so adding noise increase the amount of information in the frame but possibly not wanted info. Less captured noise is more info of the scene and less random info. Normally downsampling helps reduce noise.
Furter more when comparing the cameras. Exposure is important. it´s obvious that the exposure for each camera in this test might have been the same or at least not fully optimized for the camera in question. As most of these cameras have different DR layouts and also DR widths. That makes huge difference when he zoom in and talk about detail resolution on images where noise is visible. Simply when you see noise in an image that is considered underxposure. Sure that could be done to taste but when comparing the resolution off two cameras it´s possibly good practice not to introduce noise as noise lowers resolution. Compressed noise even more so.
So the grain determines the detail, and when shooting compressed the grain / noise ratio is deteriorating the image in a exponential way. So looking at the cameras and not talking about the difference in DR layouts is simply not right at all. He might as well shoot with the lens cap on with one of the cameras and say look it does not look any different in 4k or 2k or SD.
Downscaling an image from 6k to 4k can not be done with even numbers. It also does not give you an image where the camera is having info for red green and blue for each pixel. It´s also very much important what downscale algoritms is used. It´s also very important if there was an OLPF in play or not and if sharpens is applied before or after downscale (sharpens should normally be applied if OLPF is in use)
The talk in the end about multiple resampling for different mastring formats etc. Sure might apply to some but today it´s quite possible to stay in native resolution and create masters from it and then downsample with even numbers. For example shoot 8k create a UHD master and what ever needed DCP straight from there and then create the HD master from the UHD master. Which is resolution devided by 4... Which is not really that destructive. And if wanted the HD master could also be driven straight from the native source resolution. We work that way and it works well.
Then also not to mention when stablizing images oversampling makes huge difference. Simply its quite difficult to rotate a picture with a fraction without loosing a lot of sharpens. Rotating a 8k frame and setting it down in a 4k frame is far better results than scaling it down to 4k and then rotate it... simple as that, resolution matters.
The theater bit with the shart of the screens etc. I have a 5k LG oled screen for my mac I also have several lower resolution displays of the same size and HD macbook´s and 4k laptops. Now those that can not see the difference when playing a 4k feed on a 4k laptopscreen instead of a hd feed need glasses or you need to put you laptop on your lap, simply you see the difference. I also got a 4k 65" oled screen, and when watching anything HD I dont really care if I sit in the back seat or up front but when watching the netflix Dolby vision 4k stuff... then I really want to move up close, why is that. Why am I seeing such big difference between netflix HD and Netflix UHD even if they are both heavily compressed?
Also Better Call Sal to me it looks horrible in 4k but when looking at my shitty macbook pro in HD it looks quite fine. It´s a dragon shot series but to me they went too high on iso and did pretty shitty post, noise all over the place and focus is not always right, bleading windows and so on. So when watching it in 4k I see all those errors. House of cards season 4 shot with the same camera, the quality when watch in 4k vary but way better overall than The Better call Call stuff.
Now I had an epic for several years, then dragon and now helium. Sure 3 different sensors and 3 completly different cameras, with different bitrates etc. I use them for all sorts of things VFX work, stills and normal filming stuff.
You do not need to be a rocket scientist to see that it´s really like 1,2,3 in picture quality. And yes again more things than the K´s differ but someone would need more than 2 hours to convince me that they are equal when it comes to creating a 4k mastered image. Simply put helium outshines the other two like mad... When creating a HD image well then difference is not as big and for SD I would not really care much which one of the 3, or I would actually take a dragon as that one has larger sensor at higher frame rates.
But sure it´s not only about resolution my 4k DJI osmo´s does for most scnearios look less then on par with the alexa XT even if the alexa has less resolution. It´s one of the few quality parameters in a camera that you can put a number on. Color accuracy noise ratios etc is nearly impossible to pin down what each camera is actually doing. So naturally Netflix, and BBC and others set a bar in resolution and then also add other spec´s that cameras must fulfill to be accepted. Normally there is a list of the most common cameras that are accepted on those lists, and usually those lists makes sense... The 600USD DJI osmo is not on the list just like the BMPCC camera for obvious reasons.
Copy pasted from there:
Björn Benckert Saw all of part two now. This is so much fud that I dont know where to start. I could pick any segment in that clip and explain why he is wrong in more ways than one. Sorry.
LikeShow more reactions · Reply · 4 hrs
Manage
Björn Benckert
Björn Benckert So lets start with the easy bits:
Why does alexa 65 look better than the XT on closeup, grain halation and so on on pretty much every test done?... Sure, you can say different sized sensor but except for that. smaller noise better hard contrast edges etc. The camera has the exact same sensor tech as the XT and the Amira and the mini the only thing differ is the pixel count and sensor size. Same pixels but more of them... image looks better in all the different zoom in tests and also in the zoom out tests and also in the noise test, and yes pretty much in every little node tree this guy shows the XL looks better than the XT....
Now alexa 65 is a (i dont remember the exact numbers but it´s about) 6.5k something c-mos camera so in other words it resolve 1/3 to 1/4 of that which is about 2.5k so when looking at the alexa XL in this 4k crop in demo what do you actually see? Well you see at best lets say 3k but it´s really not better than 2.5k upscaled to 4k. If you took a higher resolving camera like a Phase One or such and shot a 18k image and placed it into a scene with a alexa XL in a native XL sized timeline... The phase one would stand out as a razor blade.
So simply this guy is sitting looking at cameras that resolve about 3k at best and say he can not see any difference between them, or little difference between them. Then we sit and look at the same test on a heavily compressed internet feed and say we also do not see any difference at these cameras shooting something like 2k when watching them in 4k....
Also he points at film and calls it 35mm film... he does not state what ASA. on film ASA is very determine to resolving resolution. So comparing film and saying it looks like this is kind of like taking a digital camera shoot a picture and say this is what digital images looks like... does not matter if the image is shot with a iPhone or a Phase one or Alexa XT.... it´s reference for digital camera, thats how those looks. Simply the silver particles on celluloid films vary in size for different ASA. So does the resolution. Another thing looking at film as a still frame is not fare. Film vary the layout of the silver flakes from one frame to another so that actually gives the viewer more info about the scene when watching a clip than just a still frame. In other words film played has a different resolution than a still frame...
Noise, noise is info even if it´s unwanted info it´s info so adding noise increase the amount of information in the frame but possibly not wanted info. Less captured noise is more info of the scene and less random info. Normally downsampling helps reduce noise.
Furter more when comparing the cameras. Exposure is important. it´s obvious that the exposure for each camera in this test might have been the same or at least not fully optimized for the camera in question. As most of these cameras have different DR layouts and also DR widths. That makes huge difference when he zoom in and talk about detail resolution on images where noise is visible. Simply when you see noise in an image that is considered underxposure. Sure that could be done to taste but when comparing the resolution off two cameras it´s possibly good practice not to introduce noise as noise lowers resolution. Compressed noise even more so.
So the grain determines the detail, and when shooting compressed the grain / noise ratio is deteriorating the image in a exponential way. So looking at the cameras and not talking about the difference in DR layouts is simply not right at all. He might as well shoot with the lens cap on with one of the cameras and say look it does not look any different in 4k or 2k or SD.
Downscaling an image from 6k to 4k can not be done with even numbers. It also does not give you an image where the camera is having info for red green and blue for each pixel. It´s also very much important what downscale algoritms is used. It´s also very important if there was an OLPF in play or not and if sharpens is applied before or after downscale (sharpens should normally be applied if OLPF is in use)
The talk in the end about multiple resampling for different mastring formats etc. Sure might apply to some but today it´s quite possible to stay in native resolution and create masters from it and then downsample with even numbers. For example shoot 8k create a UHD master and what ever needed DCP straight from there and then create the HD master from the UHD master. Which is resolution devided by 4... Which is not really that destructive. And if wanted the HD master could also be driven straight from the native source resolution. We work that way and it works well.
Then also not to mention when stablizing images oversampling makes huge difference. Simply its quite difficult to rotate a picture with a fraction without loosing a lot of sharpens. Rotating a 8k frame and setting it down in a 4k frame is far better results than scaling it down to 4k and then rotate it... simple as that, resolution matters.
The theater bit with the shart of the screens etc. I have a 5k LG oled screen for my mac I also have several lower resolution displays of the same size and HD macbook´s and 4k laptops. Now those that can not see the difference when playing a 4k feed on a 4k laptopscreen instead of a hd feed need glasses or you need to put you laptop on your lap, simply you see the difference. I also got a 4k 65" oled screen, and when watching anything HD I dont really care if I sit in the back seat or up front but when watching the netflix Dolby vision 4k stuff... then I really want to move up close, why is that. Why am I seeing such big difference between netflix HD and Netflix UHD even if they are both heavily compressed?
Also Better Call Sal to me it looks horrible in 4k but when looking at my shitty macbook pro in HD it looks quite fine. It´s a dragon shot series but to me they went too high on iso and did pretty shitty post, noise all over the place and focus is not always right, bleading windows and so on. So when watching it in 4k I see all those errors. House of cards season 4 shot with the same camera, the quality when watch in 4k vary but way better overall than The Better call Call stuff.
Now I had an epic for several years, then dragon and now helium. Sure 3 different sensors and 3 completly different cameras, with different bitrates etc. I use them for all sorts of things VFX work, stills and normal filming stuff.
You do not need to be a rocket scientist to see that it´s really like 1,2,3 in picture quality. And yes again more things than the K´s differ but someone would need more than 2 hours to convince me that they are equal when it comes to creating a 4k mastered image. Simply put helium outshines the other two like mad... When creating a HD image well then difference is not as big and for SD I would not really care much which one of the 3, or I would actually take a dragon as that one has larger sensor at higher frame rates.
But sure it´s not only about resolution my 4k DJI osmo´s does for most scnearios look less then on par with the alexa XT even if the alexa has less resolution. It´s one of the few quality parameters in a camera that you can put a number on. Color accuracy noise ratios etc is nearly impossible to pin down what each camera is actually doing. So naturally Netflix, and BBC and others set a bar in resolution and then also add other spec´s that cameras must fulfill to be accepted. Normally there is a list of the most common cameras that are accepted on those lists, and usually those lists makes sense... The 600USD DJI osmo is not on the list just like the BMPCC camera for obvious reasons.
