Sony FDR-AX100

[Alan Green]

I was reading an article at SmartReview.com, that gave another advantage of the 4K video even if you will ultimately be doing 1080p Full HD as your end result. That is that you can crop your video, just like picture, because you have 8 million pixels to work with versus 2 million in HD. So, theoretically you could zoom in 4 times. This would give a lot of creative advantages to the filmmaker. And you have a 4K master or negative, thus making you ready for the future, as 4K is coming. CES was full of 4K TVs, tablets, monitors, etc. We have to get ready for the next step in HD. Hoping the FDR-AX100 is the 4K camcorder it appears to be.

Source: Sony Handycam FDR-AX100/B 4K Ultra HD Camcorder Reviews | AX100B | 2014 | SmartReview.com

[Pavel Sedlak]

Originally Posted by Alan Green

That is that you can crop your video, just like picture, because you have 8 million pixels to work with versus 2 million in HD. So, theoretically you could zoom in 4 times.

Yes, if you mean BW screen. But if you speak about colored pictures then you need (in 422 chroma subsampling usual at professional level of work) about 4mil pixels on the chip for HD and 2x8,8mil pixels (17,6mil) for 4K 422 chip.

If you have only 8mil pixels on the chip for 4K then you must to create the rest of pixels in the signal procesor by an interpolation (from your 420 chroma subsampling).

So be careful to spoke about the quality of 4K signal from one 8,8mil pixels, it is like XF100 at HD, not like HD cameras with 6mil of pixels on the chip/chips (6mil at HD is like 26,5mil at 4K).

[David Heath]

Originally Posted by Mark Fry

Only on the same size screen (or the same viewing angle). However, just as the jump from 480 to 720 or 1080 prompted us all to go and get bigger screens, won't the next increase to 4k only really be worth having on bigger "4k-ready" screens? And on those screens, you'll want similar compression ratios to those currently used for 1080 - won't you?

The comment about "same size screen" is perfectly true and yes, the whole point I was making only holds true in that context. But that's the point. A user has a 40" screen, wants a 60". If they stick with (say) 1080 and AVC-HD, the artifacting gets magnified in proportion. Move to 4K (but at less than 4x the bitrate) and they'll be better off overall, and better off than using HD at the same (60Mbs) bitrate - without datarates becoming too unmanageable in a consumer context.

But it does mean a few things being said are over optimistic......:

Originally Posted by Alan Green

I was reading an article at SmartReview.com, that gave another advantage of the 4K video even if you will ultimately be doing 1080p Full HD as your end result. That is that you can crop your video, just like picture, because you have 8 million pixels to work with versus 2 million in HD. So, theoretically you could zoom in 4 times.

Following on from what Mark says, that may well be true if the video was uncompressed, but put it through a compression mill and once you start to zoom in, the constraints aren't just resolution but the size of compression artifacting as well.

The review doesn't actually say "zoom in 4 times" - rather "Footage in 4K can also be used for Full HD video production, as you can crop or zoom in on your footage and still maintain Full HD quality.. How much cropping you can do (whilst maintaining full HD) will depend on compression issues as well as sheer resolution.

[David Heath]

Originally Posted by Pavel Sedlak

Yes, if you mean BW screen. But if you speak about colored pictures then you need (in 422 chroma subsampling usual at professional level of work) about 4mil pixels on the chip for HD and 2x8,8mil pixels (17,6mil) for 4K 422 chip.

Leaving compression issues aside, then if you zoom in to get full HD from a quarter of the 4K screen, then you'll get fullHD *with the same subsampling as the original 4K*.

If you start with 4:2:0 4K, you'll end up with 4:2:0 HD. The 4K will have 3840x2160 luminance samples and 1920x1080 chrominance. Take a quarter by that of area and you halve all the figures - 1920x1080 luminance samples and 960x540 chrominance.

Full HD with 4:2:0 sampling.

[Pavel Sedlak]

I like to heard about sharpness of 4K pictures, but for me is quality of colors (and dynamic range) much more important then sharpness.

Some "4K numbers" look very nice, but the others are a little quiet .-) .

[Ken Ross]

^ Then I guess we won't reserve an AX100 for you, Pavel.

[Pavel Sedlak]

My note isn't about that one 4K cam .-) .

My note is only about quite usual terms of quality of the camcorder and about style of discussion. There are some pros and cons and both are relevant. If somebody present some "4K numbers", please be correct (sharpness is only the one point of view).

My point of view to 4K is to get the better possibility of art. Better sharpness isn't on my the first place because I know how this is limited by optics (lens) quality, viewer or LCD quality for focus. I really like rich but natural colors, big dynamic range of chip for high contrast scenes. There is a lot of discussion about pixels count, zooming or crop possibility, but for me it is not the whole thing about 4K. I wish we have a little better disscusion about what 4K really brings (my english isn't perfect, I hope that you understand).

For example if there is the better post zoom option on the one hand, then on the other side we pay for this in color quality or DR. And we need to consider what is more important for our sort of the art. A very sharp image often doesn't looks very naturally (with the cheap lens and a lot of interpolation at signal procesor, low color quality and low DR), it is some another problem in this digital times, etc. No doubt that 4K is king but needs a lot of investment for really good result. Really good HD camera can be for many of us a better way for wonderful quality of pictures with the good price point.

[Ken Ross]

Pavel, keep in mind this thread is devoted to the AX100 as opposed to a general discussion of all the elements of 4K shooting.

I understand your admirable desire for all aspects of high resolution shooting to improve, but this is a $2,000 consumer/prosumer camcorder and it's just not reasonable to expect 4:2:2, the highest quality lens and better compression codecs to prevail at this price point.

Personally I think it's nothing short of amazing to be getting this much for this little at this point in time.

For everything to come together as you wish, I believe, at least in 2014, we're talking about a device that few of us could afford. :)

[Glen Vandermolen]

Well said, Ken. This camera may very well be my first entry into 4K video. I think it will be a big seller for Sony.

[Pavel Sedlak]

Ken - I understand what you mean. At consumer part of 4K is AX100 ok. I know that the "one man band" workers used these good consumer cameras for the low cost part of their work or as the second cheap camera.

I hope that in the middle class (it's not consumer and together it's not broadcast quality of the work) we get an option from manufactures to select 4K or a very good HD camera, about 5000USD with very good quality (422, 10bit, 50Mbps long GOP or with a greater sort of compression, with good LCD and viewer, etc., and good price point).

That is why I wrote this a little opposite view, HD is not dead and we have a great chance for really good quality HD cam, if manufactures heard this from us.

[Jack Zhang]

The PXW-Z100 is ALMOST there. The cell phone camera sensor is what's preventing it from having very good picture quality. I'm certain 1'' lenses that can be adapted for the prosumer form factor can be made, or combine Boinz X with a 2/3'' native widescreen sensor, similar to the HPX600.

[Paul Rickford]

Agreed Ken, I think the AX100 is amazing value for the money and more importantly it's here now.
It's only a few short weeks since my RX10 turned up with the best looking AVCHD yet , so if the AX100's HD is as good as the RX10 with 4K thrown in and pro level manual control, i'm very happy.

[Ken Ross]

Paul, that's my thinking too. Like you, I too recently bought the RX10 and have been extremely pleased with its output.

Since the AX100 shares the same sensor, ironically much larger than its more expensive 4K siblings, and full sensor scanning (no line skipping), I'm hoping, in many respects, it will be a 4K iteration of the RX10.

Not often discussed, I'm also expecting better OIS than exists in the RX10. That's been my only area of disappointment with the RX10.

[Paul Rickford]

Ken, when I had chance to hold the AX100 at CES, I was very pleased with the OIS, both in standard and active mode, helped partly by the handycam shape and balance it's way better than the RX10 which I agree is poor at the telephoto end.

[Ken Ross]

Good to hear Paul, thanks.