[Cannikin]

when the sensor size doesn't match the frame size of the output signal, there will of course be some kind of cropping involved, but that's not relevant to what panasonic is doing with their sensor cropping.

the gh4 1.7x focal length change with video recording proves that panasonic is overcropping the sensor, because it was never designed with video as a priority.

the a7s does a near-full sensor readout, with no line skipping, pixel binning, or downsampling; it's ~1.1x crop when recording video... it's the closest thing to a full-frame readout that's ever been put on a dslr form factor camera, which means that it has capabilities way beyond anything that the gh4 can do.

Why are you pulling nonsense numbers like "1.7x" out of thin air?

The GH4 has a 4608/4096 = 1.125x horizontal crop in cinema 4k mode (1.2x in UHD), and a vertical crop of 3456/2160 = 1.6x (thanks to the 4:3 aspect ratio's taller frame). These are all exact numbers btw (the fact that these numbers divide so evenly suggests some deliberate decision). The overall diagonal crop factor in cinema 4k mode is ~1.24x, and ~1.31x in UHD over full m4/3.

The A7s has a 4240/3840 = A little over 1.1x horizontal crop in UHD (no cinema 4k), and a vertical crop of 1.3x. The overall diagonal crop factor in UHD over 36x24mm is ~1.16x.

The overall diagonal "crop factor" from the A7s's UHD to GH4's cinema 4k is 2.15x, and UHD is 2.26x. Compared to the usual 2x crop from 36x24mm to m4/3 format, this is an increase of 1/5 of a stop and 1/3 of a stop respectively.

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Last edited by Cannikin; 05-17-2014 at 01:33 PM.

[osv]

Why are you pulling nonsense numbers like "1.7x" out of thin air?

why do you keep grasping at straws? everything that you've posted looks like an act of desperation, lol

you keep making these failed comparisons, it's like you don't understand the purpose of the cameras.

"The Panasonic GH4's ability to record both DCI 4K and UHD video internally, without line-skipping or pixel binning, sets a new standard for in-camera video recording with HDSLR and mirrorless cameras. However, a potential drawback of this method is that the GH4 can only use the center portion of the sensor. This results in about a 2.3x crop factor when compared to full-frame cameras, as opposed to the typical 2x crop for normal Micro Four Thirds cameras, which puts the GH4 into slightly weird territory when it comes to using lenses."
How to Emulate Super 35mm 4K Video with the Panasonic GH4 | explora

[DSims]

which means that it has capabilities way beyond anything that the gh4 can do.

I think this is overstating it, but you make a good point that the GH4 isn't a clear winner in every regard.

anyone who does event video for a living will tell you that there is no such thing as too much low-light capability.

people keep comparing the a7s to other dslr cameras, but it clearly and obviously wasn't designed to be used like that... it's a very specialized low-light camera, for both stills and video, and there isn't anything on the market that really compares to it.

It's hard to imagine 100% of videographers will be disinterested in this camara; on the contrary, I think both still and video shooters are interested. The fact that the Sony has lower video quality specs/standards in some areas eliminates a rather narrow slice of potential customers - those demanding videographers who only shoot in good light and must have the best IQ throughout their work, yet somehow can afford only one system!


Nevertheless, I think the compromises in the Sony's video design prove that it isn't "only" intended to appeal to video pros/enthusiasts, and it will have some compelling still photo capabilities as well.

[Cannikin]

why do you keep grasping at straws? everything that you've posted looks like an act of desperation, lol

you keep making these failed comparisons, it's like you don't understand the purpose of the cameras.

"The Panasonic GH4's ability to record both DCI 4K and UHD video internally, without line-skipping or pixel binning, sets a new standard for in-camera video recording with HDSLR and mirrorless cameras. However, a potential drawback of this method is that the GH4 can only use the center portion of the sensor. This results in about a 2.3x crop factor when compared to full-frame cameras, as opposed to the typical 2x crop for normal Micro Four Thirds cameras, which puts the GH4 into slightly weird territory when it comes to using lenses."
How to Emulate Super 35mm 4K Video with the Panasonic GH4 | explora

Grasping at straws? Everything you've posted about the GH4 is totally false. Using nothing but misinformation and random numbers pulled out of thin air to support your argument? I provide factual information and precise calculations. Who's the one that's desperate?

[osv]

Why are you pulling nonsense numbers like "1.7x" out of thin air?

i think that i failed to mention that 1.7x calc was with a speedbooster on the camera.

sorry for the confusion, i was looking for the best case scenario.

---------- Post added 05-17-2014 at 01:46 PM ----------

Grasping at straws? Everything you've posted about the GH4 is totally false. Using nothing but misinformation and random numbers pulled out of thin air to support your argument? I provide factual information and precise calculations. Who's the one that's desperate?

so you call your post of: "I struggle to imagine practical situations where you would need to shoot video much higher than that.", factual information? really?

[Cannikin]

so you call your post of: "I struggle to imagine practical situations where you would need to shoot video much higher than that.", factual information? really?

Yes.

I, Cannikin, struggle to imagine practical situations where one would need to shoot video at much higher than ISO 3200.

Is there something ambiguous about that statement?

[DSims]

Everything you've posted about the GH4 is totally false.

Perhaps a slight exaggeration? Even Satan doesn't make every statement totally false.

ISO 1600-3200 looks great as it is on the GH4 (Panasonic GH4 4K ISO 1600-3200 - Monterey Bay Aquarium - YouTube), and I struggle to imagine practical situations where you would need to shoot video much higher than that.

The night scenes in the woods at the end of the movie "Gone" were interesting. I haven't seen it in a while, so forgive me if I get some detail wrong. But I remember thinking the film vs. digital choice was very important there. The director managed to capture the characters in very dark surroundings with little or no added lights - the light from a lantern within the frame appeared to be all there was at some points. I thought it was very effective, and something I've rarely seen done.



I believe the GH4 was only brought up as a (very good) argument that the a7S couldn't be designed only for video enthusiasts, because they would have included some better capabilities and specs.


And I believe the fact that both of you are creating posts quicker than I can (I'm a touch typist) indicate someone may be putting little thought into his statements.



We won't know for sure until the a7S is released, but we've come up for some good arguments that the OPs hopes may come true (that it's a significant advancement in low-light stills performance at this price point).

[osv]

Nevertheless, I think the compromises in the Sony's video design prove that it isn't "only" intended to appeal to video pros/enthusiasts, and it will have some compelling still photo capabilities as well.

that's kinda what i thought as well... gh4 vs. a7s are different horses for different courses.

the market has never seen anything like the a7s, so it's easy to get confused about it's intended usage... if you need stills and video in low-light venues, it's the best choice by far.

if i were to get a dslr form factor, it would probably be a blackmagic global shutter camera, but that's a whole 'nother series of compromises.

[DSims]

if i were to get a dslr form factor, it would probably be a blackmagic global shutter camera, but that's a whole 'nother series of compromises.

Likewise, I'd go with BlackMagic too. But I'd have to use a K-mount adapter, or else buy a whole new set of lenses!

[Cannikin]

I'm sure A7s has fantastic stills and 1080p IQ. I was never contending that, just like there is not really any contention that FF has a 1-2 stop low light advantage over any APS-C or m4/3 camera of the same technology generation. If you want a portable 1080p camera that is great at low light, this is one of the better choices.

However, the original point was that Sony is making a huge deal about this being a "4k camera" which is disingenuous IMO. There are a lot more things important to videography than just low light noise, and the A7s falls short on most of them in 4k shooting compared to the competition. Video is a very, very different animal from stills. Very few who want 4k as a primary feature will pick this up over the GH4 for cost, convenience and advanced features/connectivity, or would rather spend just 33% more (over the minimum $4500 for 4k) for something like this: Blackmagic Design URSA 4K Digital Cinema Camera CINECAMURSA4K/EF which is a far, far more capable video camera in every respect. 4k video on the A7s sits in some no-man's land, where, besides low light noise, it is inferior to cameras both well below and a little above its price point. To me, "4k" is just tacked on as a marketing gimmick, and not really a serious selling point to discerning videographers.

Besides, with Sony's track record with pushing out cameras with incremental upgrades at a breakneck pace, they will be releasing a FF camera with "proper" 4k features in a less than a year anyway. Save your money and wait for that if FF 4k is your main point of interest.

And just for reference, a scene with f/2.8, 1/50s shutter speed and ISO 3200 is about EV 3-4. A typical night street scene is EV ~4-8 depending on traffic/lighting density, and a shot of people lit by a decent size campfire is about EV 5. Reference: Ultimate Exposure Computer

[osv]

If you want a portable 1080p camera that is great at low light, this is one of the better choices.

perhaps i need to sum up the crop comparisons between the two cameras once again?

a7s: 1.1x focal crop when shooting video
gh4: 2.3x focal crop when shooting video

that huge cropping loss totally limits the low-light capability of any sensor... i suspect that the light gathering ability of a 2.3x equivalent lens is going to be less than that of a full-frame lens, which is why people resort to things like speed boosters.

There are a lot more things important to videography than just low light noise... not really a serious selling point to discerning videographers.

fyi, people who do this for a living(clearly not you) don't want the gh4, they want the sony fdr-ax100 4k camera... to give you an idea of the interest level for that cam, there is an 85-page thread for it at dvinfo.net:

"CES 2014: Sony FDR-AX100 Consumer Cam $2,000
I had a feeling Sony would release a lower end 4K consumer cam. Didn't expect this one.
1" CMOS sensor and XAVC-S only upto 4K 30P.
12X zoom lens
Built in ND-filters
720p/120fps
$2,000 and etc.
Sony FDR-AX100 at DVinfo.net

And just for reference, a scene with f/1.4, 1/50s shutter speed and ISO 3200 is about EV 1-2. A typical night street scene is EV ~4-8 depending on traffic/lighting density, and a shot of people lit by a decent size campfire is about EV 5. Reference: Ultimate Exposure Computer

the gh4 has marginal iso performance, and there are audio issues... it's a nice toy, but still only a toy.

"...Audio appears to be fairly decent, with one exception: there’s very low-level electronic noise present, at least with most third-party microphones. Crank the headphones to maximum, and you can hear a buzz like a motorboat, varying with shutter speed and with assorted camera operations.

In most real-world recording (at least, everything I’ve tried so far), the buzz is swamped by ambient audio, but in a recording studio environment it could be an issue.

The buzz has its own webpage, the full conversation is on dvxuser, and a discussion with Panasonic is on Facebook.

...Noise builds up gradually to ISO 1600, then gets blotchier at 3200 and downright obstreperous at ISO 6400; ISO 6400 pix look more like impressionistic paintings than movie frames. Trailing artifacts aren’t noticeable at ISOs below 3200; at 3200 they’re present but mostly harmless; at 6400 it’s a special effect, like the output from a Vidicon tube camera. Color holds up fairly well, but the shadows go noticeably purple at ISO 6400.

QHD or 4K, seen as QHD or 4K, will show similar characteristics.

FHD, and QHD downsized to 1920 x 1080, look considerably cleaner – mushing pixels together boosts signal more than noise. Also bear in mind that Cine D shows more shadow noise than other looks; using STD or NAT instead of Cine D, I can at least double ISO before I’ll see the same level of noise as I do in Cine D. (In fairness, Cine D is intended as a “flat” look for later grading; one should boost the contrast and crush the shadows a bit, whereas I was looking at it as it was shot.)

I’ll happily shoot up to ISO 800 or 1600 in FHD or QHD for HD delivery. 3200 is OK for emergencies, but I’d reserve 6400 for a Vidicon-emulation look (in monochrome, it’s quite convincing)."
Review: Panasonic DMC-GH4 Micro Four Thirds HD/4K Camera at DV Info Net

[Cannikin]

perhaps i need to sum up the crop comparisons between the two cameras once again?

a7s: 1.1x focal crop when shooting video
gh4: 2.3x focal crop when shooting video

that huge cropping loss totally limits the low-light capability of any sensor... i suspect that the light gathering ability of a 2.3x equivalent lens is going to be less than that of a full-frame lens, which is why people resort to things like speed boosters.


fyi, people who do this for a living(clearly not you) don't want the gh4, they want the sony fdr-ax100 4k camera... to give you an idea of the interest level for that cam, there is an 85-page thread for it at dvinfo.net:

"CES 2014: Sony FDR-AX100 Consumer Cam $2,000
I had a feeling Sony would release a lower end 4K consumer cam. Didn't expect this one.
1" CMOS sensor and XAVC-S only upto 4K 30P.
12X zoom lens
Built in ND-filters
720p/120fps
$2,000 and etc.
Sony FDR-AX100 at DVinfo.net

the gh4 has marginal iso performance, and there are audio issues... it's a nice toy, but still only a toy.

You claim the GH4 is a "toy" for its "huge crop" and yet tout the AX100 with its 1" sensor and 2.72x crop over FF (2.85x crop in video mode assuming full sensor width) and not 1:1 pixel readout (which you claim is such a great feature that both the GH4 and A7s have) as the "professional's choice"? You're full of it.

I think it's pretty clear now that you have no argument at all, except "m4/3 sucks". I'm done talking to you.

[osv]

You claim the GH4 is a "toy" for its "huge crop" and yet tout the AX100 with its 1" sensor and 2.72x crop over FF (2.85x crop in video mode assuming full sensor width) and not 1:1 pixel readout (which you claim is such a great feature that both the GH4 and A7s have) as the "professional's choice"? You're full of it.

typical m4/3 fanboi, lol

"1" Exmor R® CMOS sensor w/ Direct Pixel Read Out"
4K Camcorder with 1" sensor - FDRAX100/B Review - Sony US

i think that the sony is 14mp for video recording... 20mp for stills on the sony, vs. 16mp for stills on the gh4.

"With about 5X the real estate of Micro Four Thirds for 3840 X 2160 UltraHD recording (that’s the math), the A7s has a huge quality advantage over the Panasonic GH4 on sensor size alone. I suspect that it will set new standards relative to its price range.

So while I’m really liking the breakthrough detail of 4K video with the Panasonic GH4, what strikes me is just how limited the small sensor it is at dusk (even at ƒ/2)... Even downsampling the GH4 video at 4K down to 1080p shows visible quality limitations. High quality imagery at night is going demands a sensor with outstanding photon-collecting power. Hence the Sony A7s comes to mind.

My impression is also that the dynamic range of the smaller sensor has its limits under more brightly lit conditions. The Sony A7s with its 14-bit sensor should be able to process that dynamic range into outstanding 8/10/12 bit video output, though the flip side appears to be the requirement for external recording for 4K capture.

Reader James K aptly points out that depth of field on full frame will be about two stops less than on Micro Four Thirds, e.g., the format equivalent depth of field at ƒ/2.8 on a Micro Four Thirds camera like the Panasonic GH4 is ƒ/5.6 on full frame."
Thoughts on Panasonic GH4 and GH4 Video Quality vs Sony A7s (Sensor Size)

[johnmflores]

DOF is a two-edged sword. Sure you can get some beautiful OOF effects with a full frame sensor but keeping the subject in focus is sometimes a challenge. I recently shot a series of sit-down interviews with a 5DIII paired with a 70-200 F2.8 zoom. I never shot faster than F5.6 (pushing the ISO as needed) and even then I was worried that the subject would lean out of the plane of focus. On the other hand, I've also shot similar sit down interviews with the GH2 and was more confident at F4.0, F3.2, and even F2.8 at wider FLs. God bless those guys that shoot run and gun with FF cameras; I hope they've got a lot of B-roll.

[ElJamoquio]

The only thing that's different is the reported ISO. The noise for the smaller/larger sensor is the same at the same DOF, assuming the same sensor technology (including not skipping lines).