Canon HF G30 Cinema Mode

[Dave Baker]

Having tried Cinema Mode, I find in very bright situations I sometimes get banding in clear blue sky, much like when I tried Cinestyle on my EOS 60D. In the case of the 60D I just accepted that I was pushing the codec a bit too far with the add-on profile and stopped using it, but this is a built-in effect and it is essentially the same camera as the professional XA 10!

I used Cinema Mode Standard with Contrast at -2, Colour Depth -1, Key M, Softening Filter off and manual exposure set to just remove 100% zebras in the brightest highlights. I use a Hoya ND8 over the lens, but it does not cause the problem in Manual Mode, so I have to assume it is not the problem (!). The banding is definitely baked into the camera output. As much as I'd like to, I cannot get back to the location to test adjustments for a year or two, so I ask if anyone else has had this and can either tell me whether this is a common problem, or suggest what CM settings I may need to change.

I've never had this happen in Manual Mode and this is how I am now shooting. If you can help, thanks.

[Rainer Listing]

I think the camera pushes the codec a bit too far. Probably something Canon was aware of when they restricted Cinema mode to 25P. It's a great field camera, but shouldn't be mistaken for a cine camera. I long ago came to the view that Cinema mode is a bit of a gimmick and despite the limits of the codec you're better off shooting manual and getting effects in post.

[Tim Lewis]

I have three Canon HF200 level Legria recorders and use Cinema Mode all the time. But the explanation of what this does for your footage is a mystery. To quote from the manual:

Give your recordings a more cinematic look by using the [Cinema Mode] recording program.Combine the recording program with the 25fps progressive frame rate [PF25] to get the enhanced effect of the 25p Cinema Mode.

It tells you exactly "squat" about what this setting is doing to your footage. As I set manual exposure, colour balance, focus, frame rate (25p) and audio levels as well as manual picture profile settings, limited though they be on these amateur cameras, what part of the controls of the camera is left to the Cinema Mode? Maybe shutter speed?. I do not tend to shoot in bright outside conditions and these cameras have no zebra levels, but I have never seen any banding effects on my footage. I tend shoot indoors event type footage where light is rather under present than over present.

The point of all this ramble is why can't Canon give us more information on what this mode is supposedly doing to and for our footage, instead of the circular logic of their manual wording.

[Dave Baker]

Rainer: I agree with you. I had always shot in Manual Mode using my own custom settings, but seeing how Cinema Mode raw footage measures on the WFM, I had to try it. After all, Canon wouldn't include something in one of their cameras that didn't work 100% would they? Would they? Really?:-) I have made the adjustment you suggest, back to Manual Mode!

Tim:

Give your recordings a more cinematic look by using the [Cinema Mode] recording program.Combine the recording program with the 25fps progressive frame rate [PF25] to get the enhanced effect of the 25p Cinema Mode.

I had an HF S100 and it had exactly the same useless "instruction" in the manual. I never used CM on that camera, only tested it and wasn't impressed.

I have searched for some information about CM but found nothing, so I thought I would ask here on the off-chance that someone might know a bit more. Oh well, thanks anyway.

[Don Palomaki]

There have been a number of past discussions going back more then 10 years on the CINE modes in various Canon camcorders. The following is but one of them.
http://www.dvinfo.net/forum/canon-vi...-mode-not.html
With search you will find more.

As I understand it video from the camcorders in question is 8-bit, about one bit more than would result in apparent banding in normal images viewed by people with normal eye sight under normal video recording. Thus banding can result from too few bits being allocated to the brightness range of concern resulting in visible brightness steps on playback. This is especially noticeable where there are large image areas involved. CINE mode softens the contrast in darker image areas and emphasizes gradation changes in lighter image areas, When digitized with a limited bit depth and then displayed - banding.

A solution is to migrate to 10-bit recording.

[Dave Baker]

Cheers Don

The older camcorder Cine Modes are different to that of the HF G30, so much of what is writtten does not apply. My old HF S100 had a Cine Mode, which I never used, much like the HV series where the camera controls everything, but the G30 allows manual control of shutter, gain etc.

Yes, the output is 8-bit

Thus banding can result from too few bits being allocated to the brightness range of concern resulting in visible brightness steps on playback. This is especially noticeable where there are large image areas involved.

Suggesting it is just possible that my turning Contrast down to minimum may exascurbate the problem? We just don't get those bright, deep blue Mediterranean skies here, so no amount of adjustment and testing will tell me if I have, or have not, cured it. Naturally I will have to have a fiddle!

I know you are correct about 10-bit being the answer, but retirement concentrates the mind wonderfully on what is to hand rather than what is available to buy. I get some jolly fine results from the G30 in Manual Mode but, you know, there's always that "can I wring a little more out of it?", which is why Cinema Mode came into the equation as an experiment.

[Don Palomaki]

The G30 is similar to the XA20, and the XA20 manual is similarly skimpy on what CINEMA mode means.

However, if one looks at the XF100 which has more image controls you will find there are a gamma setting, some of which are identified as "Cine." I suspect the net effect is about the same, with the higher end camcorder offering more adjustment options. Attached is an extract from the XF100 user manual that shows two Cine positions and their effect of gamma.

It is a trade off - for more bits allocated to shadow detail you give up bits for highlights. You have to fiddle around until you find the compromise that works for your projects.

[Bryan Worsley]

I ran a series of tests a while back comparing the luminance curves in Normal and Cinema Mode on my HF-G30. It was a pretty crude set up. Took shots of a printed greyscale ramp on a wall under daylight balanced illumination, brought the clips into DaVinci Resolve and examined the Waveform and Histogram plots. I deleted most of the data subsequently, but kept this one for prosterity - comparing Normal Mode (at default and with altered Image Effect settings) and Cinema Mode (Standard Filter 1, default 'Mid Key') all shot in Program AE (+12db AGC limit):

https://i.imgur.com/3GeFAPh.png

There's a fair bit of scatter on the plots (due to uneven illumination primarily) and I just could not produce a print of the gradient that reproduced 'true black', but it gives some insight at least into what Cinema Mode gamma does, which is consistent with Don's comment above:

Originally Posted by Don Palomaki

CINE mode softens the contrast in darker image areas and emphasizes gradation changes in lighter image areas

Actually I found that the default Cinema Mode (Mid-Key) profile could be manipulated in Resolve to something close to Normal Mode (with default 'Image Effect' settings) simply by adding Contrast (S-curve with lowered pivot point) and Gain. I still have the Resolve custom preset ('Power Grade') I created for that, but unfortunately not the waveform and histogram comparisons. That's not accounting for the 'softer' image in Cinema Mode though, which I concluded could not be satisfactorily compensated for by sharpening in post, with or without these global contrast adjustments.

Really, the only value I could see in shooting Cinema Mode (Standard Filter 1, that is) was that the flatter profile gives a bit more latitude for stylized grading. And obviously that's something one would anticipate and prepare for under controlled lighting conditions.

Incidentally, I see that Canon dropped Cinema Mode per se on the HF-GX10, and also Highlight Priority mode; but added 'Monochrome' as an alternative 'look' along with Wide DR. I wonder if they'll be following suit with successors to the HF-G40 and HF-G21, assuming there will be one or the other ?

As for Dave's query - as much as I'd like to be languishing on a beach somewhere in the Mediterranean (well maybe not this time of the year), weather conditions here in Quebec (emerging from a particularly harsh winter) don't permit me to verify the observations about the banding in Cinema Mode in very bright situations, but I think Don's explanation is most likely the case.

[Dave Baker]

Don: Thanks for the chart. Whether or not the G30 CM is the same as one of the curves, I would guess it is unlikely there would be much difference. All I know is CM Standard (default settings) looks and measures substantially flatter than can be achieved in Manual Mode using custom settings. At least in theory, it ought to be the best mode for wiggle room in post.

I had a play, conditions were nowhere near when I had the problem, just to get some idea of what CM adjustments will do. As you say, I will have to fiddle with it until I get it to suit, if I do, but my disadvantage is in having to wait until I get somewhere where the right conditions can be found. I shall try again here when we get a bright sunny day, but I believe I shall probably stick with modified MM.

Bryan: Thanks for taking the trouble to drag those Resolve 'scope traces out, they reinforce what I see on the Cinelerra Videoscopes.

Since the over exposure warning on my Cyprus trip a couple of years ago, the one you know about where I had to increase shutter speed and the water in the waterfall looked as though it was coming down some kind of ratchet device, I've been experimenting with different remedies including CM. I have shot a couple of projects in it, one of which, shot in this country, was perfectly OK, the other had the banding in a small number of clips. Yes the codec was being stretched, clear blue Greek sky and being shot from a boat at sea, even though I had an ND8 filter fitted.

Later the same year, after Cyprus, I was in Kefalonia and used my Cokin filters, but I found them not practical for run and gun video, too often the sun got behind the filter as I moved the camera about and caused flare. I bought a screw-in ND8, which means I will not have the Cyprus exposure problem again and, as I have never seen banding in MM, I shall be using it in again in the future.

I am recently back from "languishing on a beach" in Tenerife, as Greece closes for the Winter. It gave me the chance to meet Barry too, if you remember him. I took the opportunity to shoot some comparison shots, MM with various adjustments, and CM with default settings. I couldn't reproduce the banding unfortunately, however it did show me instances where CM could be preferable to MM.

[Ian Thomas]

As this thread is quite active but is nothing to do with cinema mode but is to do with g30 newer camera the g40 I wonder if any body else has had this happen to them, while filming today at the tele end of the lens the camera zoomed out to wide on its own I was not touching the rocker? it did this quite a few times the only way to stop it was to hold the rocker at the tele end, did a reset but no different anybody have any suggestions please

[Chris Hurd]

Ian, that might be an issue for Canon service.

Refer to https://www.canon.co.uk/support/rcc/

[Bryan Worsley]

Originally Posted by Ian Thomas

As this thread is quite active but is nothing to do with cinema mode but is to do with g30 newer camera the g40 I wonder if any body else has had this happen to them, while filming today at the tele end of the lens the camera zoomed out to wide on its own I was not touching the rocker? it did this quite a few times the only way to stop it was to hold the rocker at the tele end, did a reset but no different anybody have any suggestions please

Can't speak for the HF-G40 but I've never observed that on my HF-G30. Something not right there.

[Bryan Worsley]

Originally Posted by Dave Baker

All I know is CM Standard (default settings) looks and measures substantially flatter than can be achieved in Manual Mode using custom settings. At least in theory, it ought to be the best mode for wiggle room in post.

I know we've had this discussion before, but I just couldn't live with that soft-flat Cinema Mode look (which is hardly 'cinematic' from a contemporary perspective) and would always be looking to add contrast and sharpening. So the 'wiggle room' would mostly be in what headroom is left for Gain.

Originally Posted by Dave Baker

I took the opportunity to shoot some comparison shots, MM with various adjustments, and CM with default settings. I couldn't reproduce the banding unfortunately, however it did show me instances where CM could be preferable to MM.

Still wonder what benefits 'Highlight Priority' (on the HF-G40) might bring in such instances. I only had limited opportunity to compare Normal, Wide DR and Highlight Priority on the HF-G40 with some hastily shot samples taken in a camera store. Based on what I could glean from the Histogram profiles (YUV in this example) it looked like 'Highlight Priority' could be useful in very bright conditions. Posted this example before, but here it is again:

https://i.imgur.com/X3Y7WQv.png

On balance though I didn't think the HF-G40 added enough value, in terms of performance and 'must have' new features, to make upgrade from the HF-G30 worthwhile. In addition I didn't particularly like the subtle change in colour tone which definitely added more magenta to the mix.

[Dave Baker]

I know we've had this discussion before

That we have, but then I had only done a few tests locally rather than use it on a project.

The first project with it was shot in this country, there were no obvious problems and it intercut quite well with GoPro footage which was shot flat. I therefore decided to try it in Crete later in the year and found the banding once I got home. In fairness it was only in three clips, but that's three too many.

As no-one has come up with CM settings that are better, it is up to me to find out for myself. I shot a few clips at different settings yesterday, because it was sunny, looked at them in the scopes and tried CC. Interesting, but I doubt I shall get any really meaningful results until I am in Rhodes later this year.

[Don Palomaki]

Back to banding. Is it regardless of display used, or only on one display?

I ask because some displays are constrained to displayed bit depth; e.g., they take an 8-bit input and squash it down to 6-bits with dithering as a working approximation that works for most purposes and allows faster displays. That might contribute to the of banding as well.

Some online material for leisure reading pleasure.

TFT Central Monitor Panel Part Database
Provides information of various displays.

https://en.wikipedia.org/wiki/Colour_banding.
Monitors and Color Bit Depth Explained with Andy AstburyAndy Astburys' Photography Blog
Remove the Ugly Color Banding from Your 8-bit Footage with This Simple Trick | 4K Shooters