XD HDcam overexposing..?

[Ryan Hollings]

Just a quick question for anyone in the know..

heres a little background info > we were kinda thrown an XD HDcam this past weekend (350, on 1080I/60), with absolutely no knowledge on how to use it. It went well,, however, when playing back on a hd monitor, the whites seemed incredibly "bright", not really over exposed as the rest of the picture looked normal.
I was just wanting to know if this is normal,, or if there is something in the menu for adjusting that.. We didn't have time to much with any menus as it was a go-go-go sorta day.

We also rented the 730 HDcam, and compared to the XD, the whites being "hot/bright", whatever you want to call it, was the main difference we noticed.
We have pretty much factored out "user error" , as one cameraman has 15yrs experience of shooting, and the other with 20 (shooting film/video,etc)

Any help would be greatly appreciated.

Thanks!

Ryan

[Greg Boston]

Only thing I can suggest is this. And this is not meant to insult the intelligence of your camera operator.

The 350 zebra button defaults to showing zebra 2 which is fixed at 70%. If the operator thinks they are 90 to 100 and exposes as such, you can guess the results. In the menu, you can switch to 1, 2, or both. Zebra 1 is adjustable.

I was having some similar issues at first, but I wasn't using zebra. I've set zebra 1 to 90% and now I'll turn it on momentarily as a sanity check.

There are a myriad of adjustments to help with managing highlight roll-off including gamma 2 which has perhaps the shallowest curve but will need some color grading in post.

-gb-

[Ryan Hollings]

Thanks for the info.

Yeah, its a little tough getting thrown into something like this, without actually ever operating the camera. As I mentioned, it didn't seem over-exposed, it just seemed really bright.. just the whites.. I guess more time on the cam would help understanding it more.

[Nate Weaver]

This is not an XDCAM HD issue. It's a camera setup issue.

The F350 has 4 settings, off the top of my head, that control how white and transitions to white are rendered. There could be more that I'm not thinking about as well. Each setting effects parts of the others; they all interact.

To set this stuff up to match another camera, you would need, at the very least, a good HD monitor, a waveform monitor, a controlled indoor situation with lighting that will not change, and ideally, a greyscale sweep chart. Oh, and about an hour of time.

Very few experienced operators delve into this stuff in detail. Even if they do, they need the right setup and time to get any results worth anything.

Just chalk it up to not having the time or a DIT to help you with it. If you have to ever do it again, do everything you can to get the mismatched camera models to a DIT before the shoot.

[Ryan Hollings]

[QUOTE=Nate Weaver]This is not an XDCAM HD issue. It's a camera setup issue.

QUOTE]

Thats what I was hoping for. It was a rental, and not ever turning one on before, we never went thru any setups.. Thanks for the info.

[Alister Chapman]

I had a long discussion with the Sony engineers about this as I believe the default gamma curve is too flat and many first time users or those testing the XDCAM HD cameras report flat looking pictures or poor highlight handling. I think the new firmware might help address this (comming soon) as there are various tweaks being applied. It's my view that the factory default gamma curve should be gamma 2 or 3. To get the most out of the F350/F330 you have to play around with the paint menus a bit.

[Simon Wyndham]

Yes. The default gamma is very linear, and very limited in range.

But I don't see how this should result in ultra bright whites unless they haven't turned the white clip on at a relevant level.

For reference;

Cine curves 1,3, and 4 all go up to around 108%. Only Cine 2 rolls off before 100%.

The STD curve gives 120% output for just around 180% input. Thats VERY limited indeed. Conversely Cine2 has around 100% output for 450% input. In other words Cine 2 is giving you the absolute full contrast range capture of the CCD's. No need to use DCC at all with Cine 2. You won't gain anything.

Speaking of which, I hope they have sorted out the DCC on the XDCAM HD with the new firmware. Currently it does some really weird brightness changes.

[Thierry Humeau]

Originally Posted by Simon Wyndham

...Speaking of which, I hope they have sorted out the DCC on the XDCAM HD with the new firmware. Currently it does some really weird brightness changes....

I ran into the DCC issue today while shooting oil lamps on a table for a recreation scene. the candle light were flickering, turning DCC off solved the problem. There is definetly something weird about how DCC handles highlights.

Thierry.

[Nate Weaver]

I've noticed if you're in a Cinegamma, DCC is now moot with the new firmware. Same goes for manual knee.

[Simon Wyndham]

Yes, the cine gammas make the DCC somewhat redundant since they already have a built in knee.

[Nate Weaver]

Well, you would think that, but on the old firmware, both knee and DCC would still work.

In addition, I found the Cinegammas would place blown-out whites at different levels, depending how much was covering frame. Sometimes everything would clip at say, 85, other times I'd have clipping at over 100. Then adding DCC would either reduce those clips a few IRE, or sometimes bring them up! There was some math going on there if you looked often enough that was totally unpredictable (by human observation).

Anyway, it's all fixed now.

[Simon Wyndham]

Hmmm. The Cinegammas have fixed knees, so they should vary (other than between the different gammas). For example 75ire on one cinegamma is not the same as another. I believe Cines 1 and 2 are based on the hypergamma from the 750 V2 software, and also the same as the F900R.

The other Cines are different.

The DCC itself makes a judgement as to the importance of the highlights. For example, if your highlights do not occupy enough of the frame (according to the DCC) it will free up more of the range for other tones, and you might find the highlights actually becoming more blown out in some cases. If however the DCC determines that the highlights are more important, it will clamp them down. Also quite interesting is that the DCC doesn't just affect things above the knee point. It actually takes into account most of the tonal range apparently.

Maybe Soy have made the DCC less aggressive in the new firmware.
The only way to stop the variation is to put the DCC into FIX mode.

[Greg Boston]

Originally Posted by Simon Wyndham

Maybe Sony have made the DCC less aggressive in the new firmware. The only way to stop the variation is to put the DCC into FIX mode.

AFAIK, there is no 'FIX' mode for DCC on the HD cameras. Unless by 'fix' you're referring to the now disabled knee functions when using Cinegamma curves. As Nate mentioned, with the new firmware revision, engaging Cinegamma disables access to KNEE. All KNEE functions show a '--' setting. I told my Sony contact that it would still be nice to access KNEE functions even in a Cinegamma mode so that you can start with a template of sorts, and adjust it slightly to your own liking.

By the way, per the product brochure, the Cinegamma 4 curve is taken from the high-end Cinealta camera.

-gb-

[Simon Wyndham]

By the way, per the product brochure, the Cinegamma 4 curve is taken from the high-end Cinealta camera.

Not in the brochure I'm reading. Direct quote below;

"The CINE 1 and 2 curves are inherited from HyperGamma, which is available on
the top-of-the-line CineAlta camcorder."

Gamma 4 is far too steep a curve to allow wide contrast range. I'm afraid I am not allowed to give out the specifics of the gamma curves, but if you ask your Sony guys they may give you the information. Cines 3 and 4 are definitely not wide range capture.

As Nate mentioned, with the new firmware revision, engaging Cinegamma disables access to KNEE. All KNEE functions show a '--' setting. I told my Sony contact that it would still be nice to access KNEE functions even in a Cinegamma

Now that is VERY interesting indeed. I seem to recall that the Varicam is similar in this regard. Being able to alter the knee in the cine modes would not gain you much. They are already cramming the full range of the sensors into the output range. You should be able to get close by adjusting the knee point and knee slope on the STD gamma and adjusting black gamma. But you'll need a waveform and a good chart (annoyingly the XDCAM HD cameras don't have a test SAW output.)

AFAIK, there is no 'FIX' mode for DCC on the HD cameras.

Not on the 330 and 350 no. On many of the other cameras including XDCAM SD the DCC factors can be precisely set.