Sony a77 appears to fake video specs!

Started Feb 26, 2013 | Discussions
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Alphoid Veteran Member • Posts: 3,803
Sony a77 appears to fake video specs!
3

The Sony a77 is advertised to shoot 1080p video. In fact, it appears the sensor shoots something around 720p, which is further cropped by 20%. Then the whole low-res video is digitally upsampled to 1080p.

http://www.mitros.org/p/a77/a77_video.html

Cute, huh? I wish I could at least get out a native resolution video stream. It would save size, and limit degradation from upsampling to non-native resolution.

What do folks think? I'll cross-post to other forums later.

Sony SLT-A77
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Karl Scharf
Karl Scharf Veteran Member • Posts: 3,405
Re: Sony a77 appears to fake video specs!
2

So, get a dedicated video camera, if you are not happy with the A77 video specs!!!

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Karl Scharf >>> ( Sony SLT-A77, Rokinon 8mm, Sigma 10-20 f4.0-5.6, Sigma 18-250 f3.5-6.3, Sigma 50-500 f4.5-6.3 OS, Minolta 70-210 f4.0, Minolta 50 f1.7, Kenko 1.4x DGX ) <<<

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Alphoid OP Veteran Member • Posts: 3,803
Re: Sony a77 appears to fake video specs!
2

I'm very happy with the a77 video specs. They're quite nice. I'm not happy with the a77 not meeting those specs.

Gregg Helleren
Gregg Helleren Contributing Member • Posts: 603
Re: Sony a77 appears to fake video specs!
1

The author of that article stated that the camera was on a tripod but did not state that he disabled stabilisation. The image quality can be degraded under these circumstances.

Just a thought.

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Rashkae Senior Member • Posts: 1,167
Re: Sony a77 appears to fake video specs!

Disable stabilization to remove the crop.

123Mike Senior Member • Posts: 4,643
Re: Sony a77 appears to fake video specs!
2

Thanks for pointing this out. I'd like to test this with my A57. I *did* have the impression that more often than not, that video came out fuzzier than it ought to have been....

sybersitizen Veteran Member • Posts: 5,965
Re: Sony a77 appears to fake video specs!
1

Rashkae wrote:

Disable stabilization to remove the crop.

That doesn't remove the crop.

Clyde Thomas Contributing Member • Posts: 542
Re: Sony a77 appears to fake video specs!
1

Please post this to Dyxum.com forum.  I want to hear their user comments about it.  You'll get a much better idea of what's going on with this over there... either confirmation, or troubleshooting from those more experienced with the camera.

This is pretty epic news, if true.  Please post it to Dyxum.com and follow up.

Thanks

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RTIMD Forum Member • Posts: 73
Re: Sony a77 appears to fake video specs!
2

This isn't new, even though most Sony users will disagree (saying they "are pleased"). But even so, Sony is on par with their other DSLR rivals. Resolution wise it's similar to Canon's 7D. A77 Falls short vs Panasonic GH's and the new Nikon D5200.

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philbot Contributing Member • Posts: 846
Re: Sony a77 appears to fake video specs!

Alphoid wrote:

The Sony a77 is advertised to shoot 1080p video. In fact, it appears the sensor shoots something around 720p, which is further cropped by 20%. Then the whole low-res video is digitally upsampled to 1080p.

http://www.mitros.org/p/a77/a77_video.html

Cute, huh? I wish I could at least get out a native resolution video stream. It would save size, and limit degradation from upsampling to non-native resolution.

What do folks think? I'll cross-post to other forums later.

Whilst it could be true, I'd like to see what the other cameras did in the exact same test. The reason I say this is that I've never seen a 1080p video frame that looked as good as a downsampled jpeg.. they either look over sharpened, or soft..

Saying that, I never thought the A77 video was anything special, but it seems more then good enough for my usage..

TrojMacReady
TrojMacReady Veteran Member • Posts: 8,683
Am I missing something here?
3

First, I don't see a comparison between the 1080p and 720p output from the sensor itself.

But more importantly, the author doesn't take into account that there are many ways to read out a sensor in video mode, most of which do not give the same results as obtained from downsampling a still image with a good algorithm. The elephant in the room causing softness (and moire) is line skipping, done to cut down on heat, power consumption etc. This means that not all the lines and/ or columns of the sensor are read out, because the video resolution is only about 2MP from the full 24MP, whereas downsampling a full resolution still image usually doesn't ignore information but rather combines or summarizes if you wish. Most DSLR's still do this line skipping to some extend. The Panasonics and possibly D5200 are an exception in the non FF ILC class. But resolution wise, the A77 is no worse than Canon APS- C cameras. Even a hair better according to tests.

Note though that line skipping is not the same as upsampling or faking.... So to suggest some kind of fraud based on his test like he did, seems like jumping to conclusions at best (it's an apples and oranges comparison).

TrojMacReady
TrojMacReady Veteran Member • Posts: 8,683
And another important detail missing
2

The author does mention the extra 1.2x crop but doesn't mention whether he turned off stabilization or not. The crop stays either way but the digital stabilization does visibly soften output.

IanML Senior Member • Posts: 1,653
Re: And another important detail missing

TrojMacReady wrote:

The author does mention the extra 1.2x crop but doesn't mention whether he turned off stabilization or not. The crop stays either way but the digital stabilization does visibly soften output.

That's true when viewing a sequence of frames at replay speed.  However, I understand that the stabilization simply repositions "oversize" frames against the crop mask, rather than processing  the individual frames, so an individual frame (which the OP took for his experiment) will not be affected.

I think the line skipping explanation is much more likely.

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Ian

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Alphoid OP Veteran Member • Posts: 3,803
I don't think it's line skipping

There are a few standard ways for sensors to downsample from 24MP to 2MP (pixel binning and line skipping are the most common), and many more done in software (but too CPU-intensive for a camera). I believe none would lead to addition blur -- they would just give additional aliasing and moire.

TrojMacReady
TrojMacReady Veteran Member • Posts: 8,683
Re: I don't think it's line skipping
3

Alphoid wrote:

There are a few standard ways for sensors to downsample from 24MP to 2MP (pixel binning and line skipping are the most common), and many more done in software (but too CPU-intensive for a camera). I believe none would lead to addition blur -- they would just give additional aliasing and moire.

Actually, video softness is widely linked to line skipping (or a combination of line skipping and binning as Canon is suggested to use). Even if the scaling through line skipping itself wouldn't soften the visible output that much, it measurably takes away a ton of resolution and adds boatloads of moire and aliasing. The latter two are best battled with... softening (either through software or a specialized OLPF).

As Sony explains in their high end F65 promotion material (that camera downscales its 4K output from 8K), debayering obviously eats up extra video resolution, in which case sampling from a higher resolution without skipping helps detail and accuracy. That's what you did using a Lanczos filter in Gimp with the still image...

Here and here are two articles that shed some light on it too (even though there are assumptions about the methods used, the theory of sampling explained does make sense).

Apparently most camcorders sample their 1080P signal from a higher resolution (3 to 4 MP) to compensate for the debayering effects.

Just Having Fun Veteran Member • Posts: 3,869
What does he mena by, "lack of focus zoom"?

The best part of SLTs is their focusing during video (it is amazing).  It is better than then GH2 and DSLRs.

I do agree that out of all the DSLRs and mirrorless cameras I have owned, the A77 has the lowest res output.

Alphoid OP Veteran Member • Posts: 3,803
Re: What does he mena by, "lack of focus zoom"?

Switch the a77 to video mode and manual focus. Hit the focus zoom button. Nothing happens. Switch the mode knob to any of the other modes. It zooms in on a small area.

Focus zoom is one of the biggest advantages of EVFs. It lets you focus much more accurately than autofocus with fast primes. For me, it really came into its prime when I realized I could tweak focus by leaning my body a few inches forwards and backwards (rather than turning the focus knob). My a77 is always in MF mode. My procedure for semi-static photos now is:

  1. Hit AF/MF to get a course focus.
  2. Hold down AEL to get focus zoom (that's what I AEL mapped to).
  3. Lean in/out a few inches to get perfect focus.
  4. Sometimes re-position framing.
  5. Shoot.

The ergonomics of the a77 make this very fast. On the a55, this was mostly worthless (no AF/MF button, and focus zoom in a cumbersome location).

Sadly, this doesn't work for videos. Even more sadly, the camera moves the lens on start-up, so the a77 has to be refocused many times if you have a longer shooting session.

Shield3 Senior Member • Posts: 2,440
Re: Sony a77 appears to fake video specs!

Alphoid wrote:

The Sony a77 is advertised to shoot 1080p video. In fact, it appears the sensor shoots something around 720p, which is further cropped by 20%. Then the whole low-res video is digitally upsampled to 1080p.

http://www.mitros.org/p/a77/a77_video.html

Cute, huh? I wish I could at least get out a native resolution video stream. It would save size, and limit degradation from upsampling to non-native resolution.

What do folks think? I'll cross-post to other forums later.

You mention the 1.2x crop factor for the a77 - it's more like 1.36.  The a99 with IS enabled is 1.2x.  The net effect with the APS-C crop is your video on the a77 is 1.86x.

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Briarios
Briarios Regular Member • Posts: 202
Re: Sony a77 appears to fake video specs!

Alphoid wrote:

The Sony a77 is advertised to shoot 1080p video. In fact, it appears the sensor shoots something around 720p, which is further cropped by 20%. Then the whole low-res video is digitally upsampled to 1080p.

http://www.mitros.org/p/a77/a77_video.html

Cute, huh? I wish I could at least get out a native resolution video stream. It would save size, and limit degradation from upsampling to non-native resolution.

What do folks think? I'll cross-post to other forums later.

I must be missing something.  It appears that the OP in the link, is direct comparing a 6000x4000 still with a 1920x1080 video frame (albeit both cropped to relative proportion). *very* interesting however, looking forward to more info on this issue. Just need the best DSLR/SLT video possible, <$1000 - 15000 for projects.  I have an a57 but would probably pick up something else for a second camera, if I could get predictably better 1080/60p video end results with it.  I landed on a57 as there seemed no better choice for near the same money.

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TrojMacReady
TrojMacReady Veteran Member • Posts: 8,683
Re: Sony a77 appears to fake video specs!

Shield3 wrote:

Alphoid wrote:

The Sony a77 is advertised to shoot 1080p video. In fact, it appears the sensor shoots something around 720p, which is further cropped by 20%. Then the whole low-res video is digitally upsampled to 1080p.

http://www.mitros.org/p/a77/a77_video.html

Cute, huh? I wish I could at least get out a native resolution video stream. It would save size, and limit degradation from upsampling to non-native resolution.

What do folks think? I'll cross-post to other forums later.

You mention the 1.2x crop factor for the a77 - it's more like 1.36. The a99 with IS enabled is 1.2x. The net effect with the APS-C crop is your video on the a77 is 1.86x.

Actually, that would imply just over 1.2x (based on APS-C cropfactor of about 1.53x).

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