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Sony Alpha a7s: Full HD Recording in XAVC and 4:2:2 UHD 4K Output via HDMI.


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Old September 10th, 2014, 02:04 AM   #121
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Re: New Sony A7s to shoot 4K video

Quote:
Originally Posted by Michael Stevenson View Post
if you shoot in 60P NO rolling shutter.
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I'm not saying it's not there in every case
So what is it now, is there or is there not? :)

The camera has rolling shutter and it can be bad depending in which situation you use it, it doesn't even have to be a fast pan like this example shows:
Shooting in APS-C reduces the RS though but it will never be completely gone. RS should not be a problem for most of us depending on your shooting style but it can make the camera useless if you for instance shoot a soccer match with a telelens and follow the players while panning, but then again, you should use a videocamera for this purpose and not a full frame photocamera.
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Old September 10th, 2014, 02:09 AM   #122
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Re: New Sony A7s to shoot 4K video

There is more rolling shutter than most dedicated video cameras. It's not just zoomed in shots or whip pans where you may find issues. Vehicles moving through a shot or shooting from a moving vehicle will all show rolling shutter artefacts. Even a mid speed pan across any strong verticals such as telegraph poles or tall buildings will show it up. But almost every other aspect of the images from the A7s are so good that I'm happy to simply avoid these types of shots with this camera. I'm lucky though, I have other cameras, so I can fall back to these when I know I may encounter RS issues. For me the A7s strength is I can pop it in a large pocket or sling it over my shoulder and take it just about anywhere and in most situations get video that is really frighteningly good considering what the camera costs.

As an owner of both the A7s and AX100 if I had to choose one which would it be? That's tough because although they really are very different cameras they both have strengths that are nice to have. The A7s produces a prettier picture and can be used run and gun, with limitations. I use the kit 28-70mm f3.5-f5.6 and it works well, good auto focus, smooth aperture changes etc. BUT and it is a very big BUT you need a really good set of ND's or a strong ND fader to use it outdoors due to the extreme sensitivity. Add to that the minimal 3x zoom and it's pretty restrictive as to what you can shoot without switching lenses and fiddling around. Sure you can add something like the new Tamron 16-300mm f3.5-f6.3 but the autofocus tends to hunt a lot more, manual focus is fiddly and you still need to mess around with ND's. I think you need to be a fairly competent cameraman and need to be very careful over lens choices etc to use the A7s for run and gun successfully. Plus don't forget the cost of all the extra lenses, filters etc adds up and makes the kit bulkier.
The AX100 on the other hand really is a grab and go camera. Easy to use, great zoom range, built in ND's. It's quick and easy to use and may get you shots that you will miss with the A7s. But the pictures are not as pretty, primarily it lacks the dynamic range of the A7s. But it is very easy to use, so well suited to those that are full auto shooters or rely heavily on auto functions to keep life simple. It's also a very compact package and as you don't need to buy extra lenses or filters it works out substantially cheaper.

Anyway, if I had to give up one, for me it would be the AX100 that would go. I would be prepared to sacrifice the ease of use of the AX100 for the better images from the A7s. But I normally shoot manually anyway. I'm used to swapping lenses, working with ND filters etc. The best camera to own is a camera you will use. It's all very well having fancy pictures and the ability to swap lenses etc. But if fiddling around means you don't use it very often, then there is no point in having it. You would be better off with a camera that you will be comfortable with, that you will use regularly.
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Old September 10th, 2014, 09:06 PM   #123
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Re: New Sony A7s to shoot 4K video

Thanks guys, I am a better photographer than a writer by far. But the incredible clarity (low light, reflections and bokeh) of the video is very usable. I bought the Camera + Shogun so I could shoot some 4K video and start working with it before most folks will ever do. I really think a Sony A7s forum should be added here.

More handheld in very low light:

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Old September 10th, 2014, 09:08 PM   #124
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Re: New Sony A7s to shoot 4K video

Another clip:

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Old September 12th, 2014, 12:44 PM   #125
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Re: New Sony A7s to shoot 4K video

We know the Atomos Shogun 4k HDMI recorder is on the way soon.

Many Sony A7s owners are planning on using the Shogun with the A7s. (In fact Sony is relying on the Shogun recording option as a selling point for the A7s against the GH4)

One of the biggest selling points of the A7s is it's SLOG-2 feature. On another forum it has been noticed that the A7s actually does NOT output SLOG-2 via it's HDMI port. (Sony underhandedly reverts it to REC 709?)

Can anybody confirm this? If this is so, why would Sony deliberately mislead their customers on the A7s? Nowhere is it stated in any documentation or description that the SLOG-2 is disabled over HDMI.

I'm hoping this is a mistake...or,...Sony is fixing this potential PR disaster soon in a A7s firmware update.

Somebody tell me that this information is COMPLETELY WRONG! (it must be wrong. I cant believe Sony would do that without stating that to their buyers first)

CT

Last edited by Cliff Totten; September 12th, 2014 at 01:50 PM.
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Old September 12th, 2014, 05:00 PM   #126
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Re: New Sony A7s to shoot 4K video

Seems unlikely - this review has some tests with SLOG via external recording and it appears to work:

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Old September 12th, 2014, 08:31 PM   #127
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Re: New Sony A7s to shoot 4K video

Please do not watch my clips here. Watch them on Vimeo. They are highly compressed here. Wow!
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Old September 12th, 2014, 09:01 PM   #128
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Re: New Sony A7s to shoot 4K video

I posted more of this on the Convergant Design 7Q 4k thread.

Did a test tonight between SLOG-2 recorded on XAVC-S internal vs. SLOG-2 recorded over HDMI.

Comparing both files on wave form scopes show some big differences. The XAVC-S file, the SLOG-s is nice and flat. However, the HDMI recorded file has substantially more contrast. Highlights at 70 IRE on XAVC-S were spread further up the scale to 80 IRE. Shadows that registered 10 IRE internal were now spread down to 0 IRE on the HDMI port.

I'm hoping A7s owners will do their own tests to confirm this. It's a bad thing that I hope we can get resolved soon.

I hope this is not a Sony "cripple" to make sure that true SLOG-2 is trapped inside it's internal 4:2:0, 1080 codec.

Right now, I'm giving Sony the benefit of the doubt and see what they say about this.

CT
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Old September 12th, 2014, 09:05 PM   #129
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Re: New Sony A7s to shoot 4K video

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Originally Posted by Cliff Totten View Post
I posted more of this on the Convergant Design 7Q 4k thread.

Did a test tonight between SLOG-2 recorded on XAVC-S internal vs. SLOG-2 recorded over HDMI.

Comparing both files on wave form scopes show some big differences. The XAVC-S file, the SLOG-s is nice and flat. However, the HDMI recorded file has substantially more contrast. Highlights at 70 IRE on XAVC-S were spread further up the scale to 80 IRE. Shadows that registered 10 IRE internal were now spread down to 0 IRE on the HDMI port.

I'm hoping A7s owners will do their own tests to confirm this. It's a bad thing that I hope we can get resolved soon.

I hope this is not a Sony "cripple" to make sure that true SLOG-2 is trapped inside it's internal 4:2:0, 1080 codec.

Right now, I'm giving Sony the benefit of the doubt and see what they say about this.

CT
Fascinating. What were your HDMI out settings and what do you record it on?
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Old September 12th, 2014, 09:14 PM   #130
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Re: New Sony A7s to shoot 4K video

Samurai Blade via HDMI to SDI.

30p A7s recording and 60i HDMI (Using Atomos 2:2 pulldown)


I'm now testing using BlackMagic shuttle (completely different recorder)....will have those results in 30 min.

So far, I'm very surprised that only the Convergant Design team has noticed this and really spoken about it.

They are saying that the A7s SLOG-2 HDMI output is really closer to REC 709 than the "true" SLOG-2 internal recording.

If this turns out to be a creative Sony "cripple" trick, I'm going to be LIVID if they refuse to fix it.

I'm not saying it is yet. I'm hoping it's a simple "bug" that Sony will fix.

Looking for more A7s testers out there,.......

CT

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Edit - I now have TWO recorders (Atomos and BlackMagic) that both confirm the same result: The A7s HDMI port ADDS contrast back to the SLOG-2 signal. Again, highlights that are 70 IRE internally are now spread to 80 on the HDMI port. Same for the shadows too, 10 IRE internal are crushed to 0 IRE on HDMI (The entire wave form shows a SIGNIFICANT difference between internal recording and monitoring and actual HDMI out)

Calling all A7s owners. Please post your own test results! We need to shake the Sony tree on this problem.

I gotta find Alister and get him to see this......

Last edited by Cliff Totten; September 12th, 2014 at 09:48 PM.
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Old September 12th, 2014, 09:54 PM   #131
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Re: New Sony A7s to shoot 4K video

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30p A7s recording and 60i HDMI (Using Atomos 2:2 pulldown)
I'm not feeling that.
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Old September 12th, 2014, 10:03 PM   #132
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Re: New Sony A7s to shoot 4K video

BlackMagic 60i HDMI capture....exactly the same problem. This is not an interlacing or pulldown problem.

Looking for more A7s testers with any HDMI recorder.

1.) Record a SLOG-2 internal XAVC-S file.
2.) Record via HDMI to any recorder that you have.
3.) Compare both files on a scope...you will see that the SLOG-2 gamma curve has been stretched and "damaged". (compared to internal file's "proper" curve on the scope)

Again, Convergent Design posted this problem not long ago on their thread.

CT

Check out the scopes. Everything above 20 IRE shifts (stretches) up...below 20 IRE shifts (stretches) down.

Edit: As you can see in the histogram, the SLOG-2 gamma log is certainly destroyed.
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New Sony A7s to shoot 4K video-together.jpg   New Sony A7s to shoot 4K video-histogram.jpg  


Last edited by Cliff Totten; September 13th, 2014 at 08:35 AM.
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Old September 12th, 2014, 10:55 PM   #133
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Re: New Sony A7s to shoot 4K video

I rented an A7s a few weeks ago and can confirm the same issue recording to a PIX240i.

Last edited by Steve Kimmel; September 12th, 2014 at 11:05 PM. Reason: typo
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Old September 13th, 2014, 06:45 AM   #134
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Re: New Sony A7s to shoot 4K video

Dear Friends,

This issue can be easily shown without a video recorder.

Just connect an A7s (set to S-Log 2) to any HDMI television.

The image will not look like normal S-Log 2, it will not be "flat", there will be more contrast.

This is not a recorder issue.

Personally, I believe that this is not an attempt to cripple this camera.

Of course, we would like Sony to allow regular S-Log 2 to be output the HDMI port, when S-Log 2 is enabled in the menu.

Respectfully,
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Old September 13th, 2014, 07:30 PM   #135
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Re: New Sony A7s to shoot 4K video

There is some suggestion on another forum that the s-log out of HDMI problem could due to which HDMI cable one uses.
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