Mmmbeats

Some further C70 video vs C300iii RAW comparisons here.

4 hours ago, hyalinejim said:

I also do a lot of run and gun type stuff and don't have time to be faffing about with getting perfect exposure...

Those post routes look very worthwhile.  I still haven't taken a look at ACES, and don't even have a working understanding of it yet.

Is there a benefit to reading the ground for exposure?  I've not heard of that one before.

I'm increasing seeing (from sources I trust) that 75 IRE zebra is the best clipping warning level for V-Log L because of the risk of individual channel clipping (at 80 IRE).

I think this is the best sequence so far for showing the camera in a variety of situations:

20 minutes ago, hyalinejim said:

So if you expose that chip so it sits at 42 IRE on the in-camera waveform for VLog-L then that should be the technically correct exposure.

Then you can note where the relevant skin tone chips fall on the waveform, and switch over to HLG to cross reference the values...

Yes, that's more or less the technique I used, though middle grey has a slightly different reference point for HLG (38 IRE is what I used).

The way I usually do exposure is by looking at the talent and figuring out where I want their skintone relative to 'normal'.  This is influenced by whether or not they are in shadow, whether it's a moody scene, the shade of their skin, etc.  I rarely drop it more than a stop below 'normal'.

Once that is established, I take a look at the highlights and whether they need protecting.  If they do, I make some kind of compromise - either I allow some elements to blow out, or I allow the skin tone to drop further than I would like.  This just depends on the aesthetic of the shot (for example I might let quite a big window blow out, but I would hardly ever let a big section of sky blow out).

Finally, if I think there is important stuff going on in the shadows I might make an adjustment to try to help them a bit (while making sure to continue to protect the highlights).  I very often skip this stage and just let the shadow area fall where it may.

Sounds long winded written down, but all of that happens very quickly and automatically.  I prefer to use false colour, but am happy to use zebras if that's all I have access to.  As you say, spot metering is a really good alternative too (though you have to work out over/under values to make it work on most of the cameras I use).

No way am I faffing about with a grey card - I want a technique that works the same across events, doc, fiction, etc. (obviously there are somewhat different approaches required for each).

If the skintones are in the ballpark of where you want them in the final grade then I find the post route is a lot more straightforward.  You're also less likely to damage them by pushing or pulling.  That's another reason why I prefer them as a starting point for exposure than middle grey.

Having said that, I do sometimes push my exposure up a bit if I have the headroom - a kind of ETTR-lite! (the coward's version 😉).

I don't really think that 'exposing properly' means always providing end goal exposure levels in-camera.  It's virtually impossible to preserve both highlight detail and ideal skin tone exposure in a large percentage of shots, unless you were to shoot on an Alexa or something (out of my budget range!). 

51 minutes ago, hyalinejim said:

I don't know for sure, but if X Rite says that the second large chip is "40 IRE" then surely it must be 18% grey.

That's the one I used. Its labelled as 40 - 50 IRE on the documentation I have. 

Righto - so I've spent this evening doing some tests using my Colorchecker Video chart to try to hunt down some answers to this.

Just in case anyone else is seeking this info, here are my findings.

I monitored Natural, V-Log L, and HGL.  Each white balanced custom, at f/2.8, 400 ISO, using shutter speed to vary exposure.

I used reflective white as a reference point for each profile, and then used the middle grey chip as a second reference.  I had to make a best guess as to which of the very similar light grey chips was 18% grey as it is not noted in any of the XRite documentation weirdly enough.

So -

The reference profiles gave readings similar to what was expected for lightest skin:

Natural: 70 IRE

V-Log L: 50 IRE

The reading for HLG was:

HLG: 57 IRE

So, reassuringly close to Alister Chapman (60 IRE), and TL;DR Filmmaker (once you adjust for skin tone).

The readings for darkest skin were much lower than expected:

Natural: 19 IRE

V-log L: 29 IRE

HLG: 18 IRE

This leads me to think that either:

1) The darkest skin tone chip on this chart is particularly dark

2) People have not calculated exposure to include darkest skin tones properly

3) I've made some kind of mistake

Overall, I'm pretty satisfied with the test results though.  The lightest figures correspond well with how I understand each curve.  I'm willing to believe that darker skin can fall along that part of the exposure range.

I hope these are useful to someone else.  I can post more about my methods (which admittedly weren't perfect), if anyone needs the info. 

I want to know what the typical reference values are for skintone exposure in HLG for standard dynamic range delivery.

I'm finding this information quite easy to source for linear and log curves, but a bit more murky when it comes to HLG.

I am aware that -

• Skintone exposure is subjective, and can vary according to artistic intent, mood, lighting, contrast, etc.
• Skintone references are a bit out of date because camera sensors have a wider DR than when they were formulated
• The whole thing is a bit euro-centric and often doesn't consider the diversity of skin tones available

However, I like having a set of values (ideally skin tone and skin highlight tone for lightest skin types, and the same for darkest skin types - I then guestimate for tones inbetween).  It helps me to sanity check, and acts as a foundation for my subsequent choices.

In other words, I'm not intending to slavishly expose every thing to the same skintone value - I just like to know where I stand!

I'll be shooting HLG on GH5 and GH5S.

For linear, I usually work to these values (for lit skin itself) :

Lightest skin: 60 - 65 IRE

Darkest skin: 45 - 50 IRE

For V-Log-L I have found these values (which are for skin highlights) :

Lightest skin: 55 IRE

Darkest skin: 42 IRE

For HLG the only info I've found is the following:

Lightest skin at 1 stop over - 78 IRE 

This is as per Gerald Undone. I like the guy a lot, but I don't quite trust his workings on this one.  He seemed to be using 18% grey at 50 IRE as his middle reference, but I'm pretty sure it's supposed to reference at 38 IRE for HLG.

Asian skintone (slightly darker than lightest skin) - 50 – 55 IRE

As per TL;DR Filmmaker.  He's another youtuber I've got a lot of time for, but I'd classify him as an 'intelligent amateur' rather than a pro.  It's pretty clear that his understanding of HLG generally was all over the place at the time of doing the tests.  Having said that, the resulting skintones looked good.

Lightest skin: 60 IRE

This is per Alister Chapman, who I would definitely trust above the previous sources.  Only thing is, it was just a fleeting mention in a video interview, so I'd like to see it confirmed, and have a way to elaborate other skintones and values.

One thing I do notice is that the upper end of darkest skin values seem to coincide with the 18% grey reference point:

 Linear: 50 IRE

V-Log-L: 42 IRE

So for HLG this would be: 38 IRE (as per ITU-R report)

Perhaps that could help in determining part of the range?

Anyways, apologies in advance if I've mangled any of the concepts or values above.  I'd like to know typical reference values for HLG, basically,

I might go wild in the country with this myself when it comes out. 

7 hours ago, Geoff CB said:

Sony has an excellent 16-55 2.8 for E-mount.

 

It will look completely the same, but you WILL get a stop better lowlight performance. Sensor crop DOES NOT effect the light level hitting the sensor. 

 

Don't think these really show how highlights behave, it's clearly a overcast day. 

It was the interiors that got me excited, but you are correct, it's hard to tell how hard the highlights are being pushed.  Part of that was just my brain going -'Sunlight!  Nice tones!'.

From the same set (Andrzej Fryda) :
 

These are the best I've seen the camera handle highlights so far.  Shot on H.265, which as I've been saying, may turn out to be the best codec option.  Also at only 135Mbps apparently.

Very promising.

Question - how is the external video from the C70 likely to perform compared to the internal codecs?

How does it work?  Is the external signal uncompressed prior to encoding by the recorder?  Is there likely to be an image-quality improvement?

I realise that I don't really know how this all works.  For example - what is the theoretical maximum bitrate?  Is that even a well-worded question? 

Some footage that is new to me (apologies if it's been posted before) :

Looks nice enough, but doesn't really address any of my concerns / areas of interest.

Okay - I'm gonna say it...

Can we please move this thread back on topic? 😉

The places where cinema cameras tend to differentiate themselves well from lower end cameras is dynamic range and highlight roll-off.  Obviously these are somewhat related, but it occurs to me that while the C70 seems to have big advantages over say, the C200, in shadow detail, it seems (from the limited footage available so far) to be less capable in the highlights.

That's what I'm seeing in the side-by-side tests (CVP and Giannis Saroukos tests).  Also, the highlight rendition in the footage so far is not stellar.  But it's hard to judge because most footage is either not very highlight rich, or has deliberate stylistic overexposure (Saroukos), which looks pretty but makes it hard for me to work out how well the camera is handling that range.  

There is also a significant (though probably not problematic) reduction in sharpness compared to the C200 RAW (and obviously the C300III RAW).

I'll be watching this quite closely because if I'm going to be spending £5K on a camera, and at this point it still seems quite likely, then it needs to have an image that elevates above the mirrorless cameras below it.  We'll see.

On 9/29/2020 at 12:10 PM, herein2020 said:

I have the GH5 with the XLR adapter and a MixPre6 as well as a C200....

By the way, I wasn't being sarcastic, I really will take heed - particularly about unplugging the mini-XLR adapters.  That's a useful heads-up.

On 9/29/2020 at 2:03 PM, Video Hummus said:

There is some footage in this one.

 

I notice he uses the H.265 mostly.  Possibly briefed to do that by Canon.  I reckon it might turn out to be the best codec for acquisition.  Better than the All-I even,

28 minutes ago, docmoore said:

Just stack a 2 or 4 stop ND with your variable so you do not reach the X point of the crossed polarizers ... which

usually occurs near the top filtration point. You can fine tune the filtration but at a lower level.

Not sure about that.  That's 3 bits of colour-tainted polarised glass before the light even hits the front of the lens.  I'm not keen!

30 minutes ago, EphraimP said:

The value of internal ND for run and gun documentary film making cannot be overstated, imho...

Yep.  Was going to post similar.  I've had the step up ring from the outgoing lens stay stuck on the VND a few times during a change.  I've been in a VND vs lens cap conundrum a few times.  Also, there's no zero ND option with VND; you have to keep screwing the thing on and off.  Annoying.

Plus internal ND is closer to fixed ND than variable ND (complicated by the 'extended range' thing you get with Canon).  From what I see the colour rendition is fantastic. 

I wonder if they are able to further tweak the internal filters knowing that they are optimising for just one sensor?  For example they could add a bit of IR suppression I'm guessing?

In any case it's a blessing, and as you say - worth quite a bit in the heat of fast-moving acquisition.

57 minutes ago, Lux Shots said:

What issues did you see using IPB in that scenario? I have yet to see an example of a difference between the two when shooting in H264.  Now, H265 looks worse probably because of 4:2:0 vs 4:2:2.

For quick changing frames it's a disaster.  I was shooting tightly framed footage of a moving carriage (from the side).  There were massive blocky compression artifacts.

Here's a funny thing - I was quite stressed out about this, because it was clearly a mistake on my part, and something I had anticipated but forgot to compensate for.

The shot, which was acquired vertically funnily enough, was part of a large-scale museum installation.

As is, I'm assuming, general practice, I sent a low-quality file to the client for approval. 

To my horror, this low-quality file was programmed into the installation 'show' (the central controlling mechanism), and the client subsequently neglected to even download the fully mastered file from me.  I kept reminding him that he had the wrong file up, but he kept insisting that it looked fine (they were working to a tight deadline, with lots of other physical and media-based elements to install).

Anyways, the exhibition has had rave reviews (including the train segment specifically) and just ended up winning a very prestigious industry award! 😅

So perhaps sometimes our pursuit of perfection is somewhat idle!   

I'm wondering which of the codec options is going to be the highest quality option, all things being equal?

I suspect that the headroom afforded to the Long-GOP codecs is going to make them superior for most situations than the All-I.

Here are the bitrates and recording times (per 64Gb) for the top settings:

XF-AVC All-I - 410 Mbps (19 mins)

XF-AVC Long-GOP - 260 Mbps (30 mins)

MP4 / H.265 - 225 Mbps (35 mins)

It seems to me that the headroom afforded the Long-GOP codecs is more generous (proportional to their compression ability) than the All-I.

I'm only going by my experience of Panasonic's implementation of compression in which 400 Mbps All-I is virtually visually identical to 150 Mbps Long-GOP in most situations.

Also, H.265 is touted as being much more efficient than H.264, so I would expect the headroom afforded it may well yield the best results overall.

Obviously there are times when you would want to use All-I in any case (as I was recently reminded when shooting moving underground trains having forgot to switch back from Long_GOP!  😬).

Any thoughts?

1 hour ago, herein2020 said:

I have the GH5 with the XLR adapter and a MixPre6 as well as a C200. I think the XLR adapter or XLR straight into the C200 is great for a single mic or a mic and a backup mic, but I learned the hard way just a few days ago that if you have multiple speakers the Mix-Pre is way better. It was a pain to manually audio duck in Davinci Resolve the two speakers that I had; the stereo mix out of the MixPre for 4 speakers was less work than manually mixing two speakers from the onboard audio.

 

For the C70 I really don't consider the mini XLR a big deal, as you mentioned it is not as bad as mini HDMI. One thing I wouldn't do though is leave the adapters plugged in, I always feel like things sticking out of a camera port will weaken the circuit board over time as they get wiggled and moved in your bag. I'd just load up on about 6 adapters, two go in my emergency kit in my car (along with memory cards, random power cables, etc), two stay in the bag with the camera at all times (since they are so small) and two go in my dedicated audio case where I keep all of my cables, the MixPre, etc. 

 

Also, for my particular use case, this camera would primarily be a gimbal camera, audio would not be that important to me.

That's really good advice, thanks.

1 hour ago, SteveV4D said:

I would say the Panasonic adaptor is as versatile as plugging directly into the camera itself.  Mounted in the hotshoe, its really becomes a part of the camera from that point on.  

I agree the C70 has features more associated with the C300 than the GH5s.  The mini XLR maybe a weaker link compared to full XLR connectors.  Much like I prefer full HDMI over micro or mini.  I only use the Pocket mini XLR for a shotgun mic for better quality background sound.  I would be reluctant to use it for bringing in audio from  say a sound desk.  I'd rather capture audio separately with maybe a backup into the camera.

I've used the DMW (if I'm getting it's name right) and it's a really good unit.  I'll probably pick one up even if I get an external recorder, and even if I demote the GH5S.  The thing is though, I'm pretty sure you are still going to want to strip the camera from time to time, whether for transport, or for a top handle, or for a smaller package.  This makes it one more thing to manage and set up, one more thing to forget to pack! (I only very rarely have a packing incident!).

Mini XLR is not as much of a deficit as micro HDMI as the connection is still locking.  I'll probably just have a pair of short adaptors permanently attached if I can find a good way to secure them ( though I admit, that's just the kind of 'riggy' stuff I'm trying to get away from).

I do generally plug a rented Zoom recorder into the sound desk for redundant sound, but end up using the camera feed just for convenience.  Events are not my main line of work, so my gear is not yet optimised for it really.  Managing to service the jobs fine though, so it's not a big problem.