AG-DVX200 4K Large-Sensor Handheld Camcorder
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combatentropy
Veteran
The bus on SDXC is 2.5 Gbps. Cards today still can't go quite that fast, because the flash inside isn't that fast. But a year and a half ago, Sandisk came out with a card that did 2 Gbps.
These are write speeds. I know read speeds are usually faster than write speeds, but yes, these are write speeds. However, Sandisk said "up to." I'm not sure what the reliable, sustained write speed is. A reviewer did get up to a 1.6 Gbps sequential write speed on it.
If you look for a guaranteed minimum sustained write speed, you'll only see 30 MB/sec., because UHS-II is the highest certificate. You can't certify it higher until the standards organization comes out with a higher certificate. But I've seen several cards that test higher than 30 MB/sec., many different brands around 100 MB/sec. (800 Mbps) write.
Even if a card only wrote at 30 MB/sec., still that's 240 Mbps. (megabits per second. MB = megabytes, which is 8 Mb, megabits. Mind your B's and b's.)
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There are new Nikon D5 rumors (early 2016 announcement). Nikon has made a number of deals with Sony in the past, including the ability to accept the XQD cards in D4. For the stills market, it didn't seem like a great idea but it all changes with 4K ... especially if Nikon also adapts the XAVC-I codec from that very well known third party vendor.
The point is "reliable, sustained write speed" for what is being talked about - and that is normally way different to the speed at which it can write short bursts. And the review you link to also mentions 30Mb/s (240Mbs) as a more typical figure.
But card specs are likely to vary within a batch, and any sensible manufacturer is going to want to have a decent safety margin - so RELYING on the 240Mbs figure is not going to be a good idea. And for current AVC based codecs, in I-frame mode at 4K, the datarate works out at around 10xframe rate Mbs. So as rule of thumb, 24p will need 240Mbs, 60p will need 600Mbs. So an SDXC card may JUST work for I-frame only 4K at 24p - but I wouldn't like to rely on it! In a few years time it may - most likely WILL
- be a different story!All else equal, for typical material, a I-frame codec is likely to need about 2-3X the datarate of the equivalent long-GOP codec for equivalent quality - more as you up the framerate. Hence, I find it fully believable that 100Mbs long-GOP will give comparable quality to 240Mbs I-frame only for 24p. Same with 150Mbs versus 600Mbs for 60p.
But the 100-150Mbs will fit comfortably within the SDXC card spec for SUSTAINED write, and still have a decent headroom for safety.
maranfilms
Veteran
Despite some great features, I just don't care to much for the images I've seen from this camera. I will have to see more to be sure, but the v-log to 709 lut looks terrible to my eyes. Hopefully someone will develop a better looking lut for this without the strong magenta tone. Shouldn't be all that difficult to make. What I find strange, is this footage has a sony look, which at times comes off like plastic.
That video shows a huge difference to the engineering version of the camera I had. There's clearly been a lot of changes made.
Agreed, the color science and the way skintones look has a lot to be desired from the stuff I've seen so far.
Sony sensor = Sony look.
MikeWilmette
New member
Hi Barry: I just put "2 and 2 together" to realize that you're the Barry Green featured at Panasonic's website who will soon publish a AG-DVX200 white paper titled "Auto Focus Performance with 4K shooting." So, I'm especially appreciative of your previous response to my question about the AG-DVX200's (lack of) auto-focus face recognition.
Unlike most of the camcorder's target market, I'm not a professional videographer but rather an occasional (but serious) amateur who benefits from auto focus. Unlike professionals, I don't get sufficient practice to reliably manually focus in fast-moving situations. So, it's perplexing (and frustrating) to me that a $4,195 camera won't have the same facial recognition focusing assistance that I get from my much less sophisticated smart phone.
So, for a serious amateur end-user like me, does the AG-DVX200 have (perhaps by some other name) an alternative intelligent focusing function that I can count on to focus on faces (on the fly)?
combatentropy
Veteran
Then don't grade it like that.
I took screenshots of the Vimeo video and spent a few minutes regrading them in the GIMP. I'm sure with the original file, more time, and more advanced grading software, I could do even better. But "plastic skin tones," "Sony look," etc. --- those are all from the grade or lack thereof.
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Aiiiiiiiyyyyyeee. Here is a good example of more of the weird greyish skin tone issue that I've mentioned in other posts. Look at her face. It's getting exaggerated by the compression of the still I grabbed, but the issue is evident even in the Vimeo file, and really, in almost every single shot of her. I wouldn't call it "plastic-y" as some are, that's maybe another issue. . .to me it's more like weirdly desaturated in places for no reason. That's too bad. . .Every other aspect of what the cam does looks really nice to me (skin tones that DON'T have the weird greyness ) depth of field, sharpness, but that skin tone thing is something I wouldn't be able to get past.
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philiplipetz
Veteran
Some people have suggested that recent codecs, such as non intraframe XVAC, have shifted the macro blocking from motion to low contrast areas. This could make thin 4:2:0 8 bit codecs fall apart under log compression and grading. I don't know however if the facial chromatic distortions that so many people see in the DVX200 could be examples of the codec failing to make subtle distinctions when shot in low contrast V Log. Worth looking at.
Take a look at the 4:2:2 10 bit externally recorded V Log footage. It shows none of these problems.
Take a look at the 4:2:2 10 bit externally recorded V Log footage. It shows none of these problems.
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philiplipetz
Veteran
The "grey" patches Josh complains about are there in your excellent regrading of the original image. That is the real problem, not the plastic look so prevalent in prematurely released samples.
That's great if the external stuff doesn't have those issues, but kind of not what the camera is supposed to be about (i.e. good quality with INTERNAL) recording. Have we seen any NON-log footage from the production models? I can't be the only one that never shoots that kind of footage unless a client specifically requests it? I don't edit that much and generally hand off/ship to someone. Unless I knew they wanted to grade or asked for it I would give them something non-LOG.
Vaughan Wood
Well-known member
I was thinking exactly the same thing! As a stage show (mainly) shooter, I would love to see the same model shot with ordinary scene files to see the 'grey' skintones are still there......"Please"?????
Cheers,
Vaughan
Bassman2003
Veteran
With all of the trauma in the GH4 world with V-log it seems to be much ado about... I don't want to say nothing but not a lot of good seems to be coming about with it around 4:2:0 8bit recording. Acting like a placebo in some cases imho. To shoot this grey mess and have resurrect your image in post seems like it only belongs in very low compression recording environments, not "run & gun" prosumer gear.
This camera is having an identity crisis as it is billed as an event workhorse and V-log is getting all of the attention. If I want this workflow I would rather use a RAW camera and really do some damage!
What is a huge deal for me but seems to get lost in the shuffle is the great color controls in the menu Barry told us about. I know baking-in is lame these days but this is the real gem for a ~$4,000 camera. Spend some time here and one can avoid the grey matter.
This camera is having an identity crisis as it is billed as an event workhorse and V-log is getting all of the attention. If I want this workflow I would rather use a RAW camera and really do some damage!
What is a huge deal for me but seems to get lost in the shuffle is the great color controls in the menu Barry told us about. I know baking-in is lame these days but this is the real gem for a ~$4,000 camera. Spend some time here and one can avoid the grey matter.
philiplipetz
Veteran
The best baked in look example from the engineering prototypes was excellent, the saturated high contrast look of the gun fight could easily be modified to tasted with built in controls, except it had red blooming on faces in places similar to where grey spots appear with V Log, on the checks. I strongly suspect that it had a different origin but only time will tell.
Mike Harvey
Veteran
Someone help me with my math... most of the V-Log stuff we've seen has been 4k, correct? That's ~100Mb/s, which would roughly be the equivalent of a 4k version of AVCHD, am I right? People are saying the skin tone issue isn't present in the externally recorded footage. Have we seen any footage recorded internally at the higher HD bitrates? I'm curious if the issues with skin tone issues are present in footage recorded at the 50mb/s and 100mb/s long-GOP and 200mb/s I-frame codecs.
Exactly this. Strangely, this problem doesn't seem to appear on GH4 V-Log footage. It reminds me of a signature problem with the venerable GH1. Skin tone, when transitioning from highlight to shadow, would inexplicably go from flesh colored to blue.