Jump to content


Photo

First job with F900


  • Please log in to reply
11 replies to this topic

#1 Michael Maier

Michael Maier
  • Basic Members
  • PipPipPip
  • 215 posts
  • Camera Operator

Posted 10 March 2008 - 01:51 PM

I got a gig to shoot a feature with the F900 but I have never used any of the F900 cameras before.
We shot some tests yesterday and it came out quite noisy in the shadows, specially given the walls in one of the sets is very dark wood. All together a pretty dark room and there are many scenes taking place in this set where the only light source should be a desk lamp and moon light, or a desk lamp and day light breaking through the blinds. As I'm not familiar with the camera I shot the tests with it pretty much on default with the exception that I used Hypergamma 4. I'm starting to think we will have to shoot it bright, get the contrast ratio close enough and get the dark room effect in post.
Could anybody give any advice in how to get the best out of the camera and how to avoid noise and image degradation when shooting low light scenes? There will also be night exteriors.
  • 0

#2 Elhanan Matos

Elhanan Matos
  • Sustaining Members
  • 432 posts
  • Digital Image Technician
  • Santa Monica, CA

Posted 10 March 2008 - 02:52 PM

Hey Michael,

What you need to do for your low light scenes is shoot with hypergamma 3 and set your gain to -3 db. Then when you go back to a more high contrast scene go back to 0db gain and hypergamma 4. If that does not help then you should put the camera back into a standard gamma table 5 and coarse gamma 0.45 and check your shadows again, if it is still too noisy send it back to the rental house and ask them to take a look at the camera for you, because the gain might be set too high on the optical head block.
  • 0

#3 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11937 posts
  • Other

Posted 10 March 2008 - 03:02 PM

The only thing that's burned into my brain about F900 is the inane "hold down the button while switching on" engineering menu access.
  • 0

#4 Michael Nash

Michael Nash
  • Sustaining Members
  • 3330 posts
  • Cinematographer
  • Pasadena, CA

Posted 10 March 2008 - 03:41 PM

The only thing that's burned into my brain about F900 is the inane "hold down the button while switching on" engineering menu access.


That's pretty common for many professional Sony cameras, not just the F900.
  • 0

#5 Michael Maier

Michael Maier
  • Basic Members
  • PipPipPip
  • 215 posts
  • Camera Operator

Posted 10 March 2008 - 07:51 PM

Hey Michael,

What you need to do for your low light scenes is shoot with hypergamma 3 and set your gain to -3 db. Then when you go back to a more high contrast scene go back to 0db gain and hypergamma 4. If that does not help then you should put the camera back into a standard gamma table 5 and coarse gamma 0.45 and check your shadows again, if it is still too noisy send it back to the rental house and ask them to take a look at the camera for you, because the gain might be set too high on the optical head block.



Thanks Elhanan.
I will give it a try . We still have more tests to do.
I used the hyppergamma 4 with -3db too.
I like using -3db as much as I can.

Edited by Michael Maier, 10 March 2008 - 07:54 PM.

  • 0

#6 Michael Maier

Michael Maier
  • Basic Members
  • PipPipPip
  • 215 posts
  • Camera Operator

Posted 11 March 2008 - 05:41 AM

Another question. Do you guys find yourselves under exposing or slightly "over exposing" to get the best and most flexible image for post manipulation? I have always under exposed SD video a bit, but there seems to be two different schools when it comes to the F900. Some swear by under exposing while others say if you under expose you are wasting data and you should slightly over expose without letting the image clip. Just get it slightly towards the right on the histogram. I personally hate video clip so I'm always more comfortable under exposing a bit, which I did in the tests. Maybe that was what caused noise and I would have been better off if I had over exposed a bit instead and brought the levels down in post?
  • 0

#7 John Brawley

John Brawley
  • Sustaining Members
  • 834 posts
  • Cinematographer
  • Atlanta Georgia

Posted 11 March 2008 - 04:27 PM

. I personally hate video clip so I'm always more comfortable under exposing a bit, which I did in the tests. Maybe that was what caused noise and I would have been better off if I had over exposed a bit instead and brought the levels down in post?



I agree. Nothing says electronic imaging more than overexposure. It's such a fine line though and you still have to protect you shadows. Maybe that is why you're getting more noise than you expect once you lift them up again. You have to underexpose, but not TOO much...

If you're still not happy with a half to 1 stop under, then I'd normally go back to set and start modifying the lighting, either filling or flagging etc.

This is when I shake my head because the predominant thinking is that electronic imaging is much faster to shoot. I find to do it well and in a controlled and *filmic* way, it actually takes the same or longer to light compared to film.

jb
  • 0

#8 Michael Nash

Michael Nash
  • Sustaining Members
  • 3330 posts
  • Cinematographer
  • Pasadena, CA

Posted 11 March 2008 - 04:44 PM

This is when I shake my head because the predominant thinking is that electronic imaging is much faster to shoot. I find to do it well and in a controlled and *filmic* way, it actually takes the same or longer to light compared to film.


Yes, it's much more like shooting reversal, where you've really got to nail your exposures. There's definitely a narrow "sweet spot" for exposure where you get the best "density" (in this case, it's signal-to-noise ratio).

I'm not a fan of underexposing video, although sometimes you get into a pinch where you just really don't want to blow out or clip certain subjects. In those situations I often like to tweak the camera settings (gamma & black stretch in conjunction with exposure) to protect the highlights, rather than just underexpose. That way, you at least get to see what the signal looks like rather than having to guess how it will look after recovery in post. But I realize that approach is not always possible or practical on every shoot.

But in general, I'm a proponent of trying to nail the exposure as much as possible with video, simply because the image tends to fall apart so quickly if you get wrong.
  • 0

#9 Michael Maier

Michael Maier
  • Basic Members
  • PipPipPip
  • 215 posts
  • Camera Operator

Posted 12 March 2008 - 02:48 AM

But I really don't think I underexposed the tests. All I did was try to get the effect in camera. It did have a lot of shadows but I didn't really underexpose them.
Is to light it brighter and get the effect in post the only way to get a clean noiseless low key shot with these cameras ?
  • 0

#10 Jonathan Bowerbank

Jonathan Bowerbank
  • Basic Members
  • PipPipPipPip
  • 2815 posts
  • 1st Assistant Camera
  • San Francisco, CA

Posted 12 March 2008 - 03:30 AM

I'm AC'ing a feature and working with the F900R for the first time. We're doing a night test tomorrow, so I'll see what happens there and let you know if I can give any advice.

Also, the DP I'm working for has the camera set to Log Mode in the Gamma settings under the "Paint" portion of the menu. Through the viewfinder, color & contrast wise, it's quite flat, but it's supposed to give you a lot more room for correction in post. It's something else to consider.
  • 0

#11 Michael Nash

Michael Nash
  • Sustaining Members
  • 3330 posts
  • Cinematographer
  • Pasadena, CA

Posted 12 March 2008 - 02:34 PM

But I really don't think I underexposed the tests. All I did was try to get the effect in camera. It did have a lot of shadows but I didn't really underexpose them.
Is to light it brighter and get the effect in post the only way to get a clean noiseless low key shot with these cameras ?


It's not a matter of exposure, but rather the signal-to-noise ratio. Noise in this case is caused by signal amplification -- specifically, the gamma and gain settings. The more the signal is boosted, the more noise there is at a given luminance. Noise in HD tends to show up the in the darkest luminances first (deep shadows just above black), and encroaches on higher luminances as you continue to boost the signal.

To minimize noise you do need to "maximize" signal -- but as we've discussed, there isn't much room to overexpose video before you get ugly image artifacts. So then you need to look at your gamma settings and find one that doesn't boost the shadow noise too much (which is what Elhanan was talking about in post #2), but still gives you the look you can use.

Paul Cameron and Michael Mann talk about their experiences with it here: http://www.theasc.co...eral/page1.html . Although they're talking about noise at positive gain settings, it's all the same principle.

So keep in mind, if there's noise in the signal at lower luminances, overexposing the image isn't going to make that noise go away. It'll just be pushed "darker" and perhaps less visible after color correction. The only way to get rid of the noise is to not boost the signal too much in the first place, and then of course don't underexpose your image to where much of it is in the noisy shadows.
  • 0

#12 Markus Rave

Markus Rave
  • Basic Members
  • PipPipPip
  • 103 posts
  • Cinematographer
  • Frankfurt, Germany

Posted 14 March 2008 - 05:35 AM

DonĀ“t know if it was mentioned before but check back focus after temperature changes or long camera running. The optical block as the whole camera get hot and if you do not have a Clairmont version (they use a custom made steel front with alsmost no change under temp changes) the back focus will change on the regular 900s.

Markus
  • 0


Rig Wheels Passport

Technodolly

CineLab

Metropolis Post

Gamma Ray Digital Inc

Aerial Filmworks

Abel Cine

The Slider

Tai Audio

CineTape

Ritter Battery

Visual Products

Opal

Broadcast Solutions Inc

Willys Widgets

Wooden Camera

rebotnix Technologies

Media Blackout - Custom Cables and AKS

Paralinx LLC

Glidecam

FJS International, LLC

Metropolis Post

Media Blackout - Custom Cables and AKS

FJS International, LLC

rebotnix Technologies

Opal

Glidecam

Wooden Camera

Broadcast Solutions Inc

Tai Audio

Gamma Ray Digital Inc

Paralinx LLC

Abel Cine

The Slider

CineTape

Rig Wheels Passport

Technodolly

CineLab

Ritter Battery

Willys Widgets

Visual Products

Aerial Filmworks