Exposure weirdness

[Ian Henderson]

I like to shoot a lot into the sun/light source for a blown-out, overexposed look for some pictures. Under these conditions it's pretty much impossible to avoid the zebras going mad, even at 80%, and indeed parts of the picture will be overexposed. But I'm from a still background...

Does it work to shoot like this, then pull the levels back in post, so that it's broadcast legal, even though it will still look blown-out, because that's the look I'm wanting?

[Alex Leith]

My understanding is that most consumer and prosumer video cameras record into the 109% superwhite range.

So theoretically, with zebras set to 100% you should still have a little lattitude and a little retrievable overexposure. (I seem to recall on my DVX there was a 105% zebra option, so you could just flag what was gone for good!)

In reality I think it probably depends on how the processor works. I've only been working in controlled lighting situations with my A1, so I haven't had a chance to experiment with this one. Perhaps 100% zebra with the Canon is actually 109% IRE [sic]. Or perhaps it records up to 109% but blows out after 100...

[Tony Tremble]

Stephen

What gamma setting are you using? I can definitely see an advantage to setting the zebras lower if you are using Cine2 gamma curve as it starts to blow out highlights well before they actually get to 100 IRE.

My setup for those that are interested.

I have found the NORMAL gamma curve give me the best highlight handling and the look that CINE1&2 give can easily be replicated in post without destroying the dynamic range while shooting.

I have the BLACK STRETCH and KNEE LOW. SETUP also affects the gamma curve and thus the highlights.

I also use a modified NOMAGENT preset downloaded from the presets section.

I find this gives me a wide dynamic range and neutral look ready for achieving the desired grade in post.

I am not suggesting this is the way to work just the way I like to work with the camera.

TT

[Piotr Wozniacki]

Tony,

A very good point about the gamma setting influencing actual latitude! I can confirm this on both the A1 and Sony V1. The zebra display doesn't account for that, and thus can be misleading (especially when set at 100%).

[Alex Leith]

So far I haven't worked with any prosumer camera that really does a particularly good job of handling highlights.

And so far the improvement with CMOS based cameras is only marginal at best.

Normally I feel like I really want to be able to set the knee a bit lower. On the A1 I can't really see any difference between the different knee settings.

[Tony Tremble]

Originally Posted by Alex Leith

And so far the improvement with CMOS based cameras is only marginal at best.

Normally I feel like I really want to be able to set the knee a bit lower. On the A1 I can't really see any difference between the different knee settings.

Indeed, the V1E does not offer any more latitude than the XH-A1 and handles highlights no better. The real benefit of CMOS is to be able to adress each pixel and make changes on a per pixel basis. The EIP in the V1 adds a bit of faux latitude with the contrast enhancer option as it lifts the blacks but at a cost of more noise.

Back to the XH-A1, I can clearly see a difference between knee settings. Good places to spot the differences are on bright curved surfaces.

TT

[Alex Leith]

Originally Posted by Tony Tremble

Back to the XH-A1, I can clearly see a difference between knee settings. Good places to spot the differences are on bright curved surfaces.TT

Oh yes. Now I see it. Not quite as big a difference as I'd like... but every little helps.

So, NORMAL gamma seems to give a wider dynamic range than either of the CINE gammas...?

What about SETUP to -9 and PEDESTAL to +9. It seems to my eyes to give a slightly flatter wider range, without washing out or crushing the blacks.

[Bogdan Tyburczy]

It is possible different manufacturers define maximum level differently. Maybe zebra 100% is what Canon defines as the peak level, maybe Pana defines it somewhat different. The key is we need some time to experiment with our cameras to learn their characteristics.

CMOS does not offer any significant advantage over CCD's dynamic range. It's the same photodiodes that receive the light, only addressing, signal transfer and integration is different.

Phenomenon Steven noticed is quite common and often unavoidable. I'm sure we all have seen it working with film or digital cameras. Even RED will suffer the same way when light is tough enough.

There's a new high dynamic range technology slowly emerging that uses sensors with special matrixes delivering 2 levels of response to light. As a result, their dynamic range is similar to human eye. It does not look like this technology will be commercially available in this decade. Maybe in 5, maybe more years from now.

[Alex Leith]

Undoubtedly a (slightly) better job can be done now, as there are high end cameras with more sophisticated DSPs that handle highlights more elegantly.

But I guess it's partly cost of technology; and partly market segmentation.

And I look forward to any technology that can improve the dynamic range.

[Bogdan Tyburczy]

Originally Posted by Alex Leith

Undoubtedly a (slightly) better job can be done now, as there are high end cameras with more sophisticated DSPs that handle highlights more elegantly.

But I guess it's partly cost of technology; and partly market segmentation.

And I look forward to any technology that can improve the dynamic range.

Of course, even SD cameras handle highlights slightly better because their photocells are larger.

HDR? Oh man, simulating it with still images I just can't wait to see that dynamic range in moving pictures! Until then, I dial Knee Low and use bounce board and screens whenever possible to balance the light better :)

[Tony Tremble]

I seem to remember Adam Wilt's write up on the shootout and the XL-H1 was the camera that handled highlights most elegantly. Canon ensures there is no hue shift towards the highlight.

TT