my first HD shooting

nicolas Khoury · May 24, 2004

last week i had my first shooting with an HD camera using the sony f900 camera.

i was shooting a scene over a town from a high mountain. in the frame there was a piece of sky showing. in the sky there was a gradual blue color (differant in brightness). on a level of blue there was something like a picture noise (the one you see on a TV when is not receiving a channel) . as i changed the "iris" the noise moved in the sky. to stay on the same blue color. it was acting a little bit like the 70% zebra on a digibeta. we could easily see it through the viewfinder and throught the 9" monitor and worst it was on the image after we did the 3:2 pulldown to a digibeta.

i have NO IDEA what this was. i am sure there was no UFO in the sky. :P

but it is a problem. luckyly the guys from the grafic department managed to hide this noise on the post production by bluring the zone of the noise but iprefer not to have such problems when shooting.

if anyone had this problem and knows how to deal with it please tell me.

+++ if anyone knows a site where i can get the operation manual of the f900 (because there is some options i couldn't access or understand in the camera)

i would realy realy apreciate your help

thank you very much

sincerely yours

Nicolas Khoury

Tenolian Bell · May 24, 2004

Sounds like chromatic aberrations everyone's been complaining about. Something to do with the prism block. I'm sure Phil could explain it better.

Mitch Gross · May 25, 2004

It also sounds like the DCC circuit was having problems clamping down the highlights in the sky. Did you have DCC switched on?

David Mullen ASC · May 25, 2004

Or a combination of the DCC and the ITU709 Color Matrix preset.

Jarin Blaschke · May 25, 2004

Hey folks -

as a newcomer to HD myself, what is DCC by the way? Thanks.

John Pytlak RIP · May 25, 2004

DCC: Dynamic Contrast Control

It is a "knee point adjustment" that attempts to reduce the loss of highlight detail in high contrast situations that tend to "blow" out highlights on digital cameras.

In effect, it tries to emulate a color negative film's gentle "shoulder" that holds highlight detail over a wide range.

Kodak worked with ASC members to compare cameras in a "Cinematographers Test":

http://www.kodak.com/country/US/en/motion/...h/35hd24p.shtml

Michael Nash · May 25, 2004

DCC: Dynamic Contrast Control

It is a "knee point adjustment" that attempts to reduce the loss of highlight detail in high contrast situations that tend to "blow" out highlights on digital cameras.

It's worth pointing out the "Dynamic" word in there...

"DCC ON" means the knee function kicks in automatically when the camera detects a sufficient area of bright highlight in the frame (kind of like the way an auto iris does). When there are no bright highlights, the knee function turns off to restore a normal looking gamma.

"DCC OFF" (middle position on the toggle switch on the side of the camera) turns the AUTO knee off, but still allows you to program the knee curve (via menus) to remain constant. This really comes in handy when the highlights in the shot are changing due to zooming or camera movement, and you don't want to see a change in gamma mid-shot (again, kind of like turning the auto iris off during camera movement and letting highlights get overexposed temporarily).

So I don't know if this function is part of your problem, but take some time to experiment with the knee/autoknee. Try this test:

Set a styrofoam coffee cup on a table and expose so that the white peaks at about 100% or even slightly higher. With the DCC ON, start on a wide shot where the cup is small in frame, then zoom in slowly on the cup until it fills the frame. There should be a point during the zoom where the picture gamma suddenly changes and you see more detail in the cup than you did before. This is the knee function kicking in.

Now try turning the DCC off and go into the camera menus to program the point, slope, and on/off of the knee function. While zoomed in on the cup, set the knee so that you see as much highlight detail as possible. Now zoom out back to your wide shot and notice how the flattened highlight response affects the rest of your image.

The moral of the story here is: DCC ON means the camera automatically tracks highlights for you, but can cause unwanted fluctuations in gamma at times. DCC OFF allows you to fix the knee ON in one spot, but it needs to be set on a shot-by-shot basis.

More can be found here:

http://jkor.com/peter/F900paint.html

Michael Nash · May 25, 2004

This also from Peter Gray's website ( http://jkor.com/peter/contentshd.html ):

Knee Aperture adds additional enhancement in the high-end frequencies. Normally you don?t need to boost the high-end detail, especially if you want more of a "film look". It can cause some "rain" on the top end, if you crank it up to high. It is not normally required, so this menu can be ignored for most applications.

-- This "rain" sounds supsiciously like the problem reported in the original post.

Mike Brennan · May 27, 2004

The f900 when in normal operating mode what (I think) you have desrcibed does not happen.

If you have saved your camera setup at the time you were shooting, to memory stick then you could check with a local expert.

The D whte balance function, shadow saturation can create noise.

Finally their could be a fault with the camera. The rental company should be made aware of this fault, follow it through so that both of you can figure out what happened.

This should have been rectified when you saw it, one of the advantages of HD is that you can see what you are doing before you do it!

Lets us know what what you conlude

Mike Brennan

nicolas Khoury · June 5, 2004

thanks for the informations.

i am going to do the tests as soon as possible

unfortunatly i did not save my setup on sa memory stick. and i am not sure if the DCC was on or off. but anyway, i am going to do the tests as soon as possible. and i will tell you what happens to me.

by the way when that problem occured, not all the highlight zone had the problem. only one part of it. there were brighter zones of the sky that did not have the noise problems.

+++ if you know an internet site where i can get the user's manual for the camera (a .pdf file or something like that) it would be great because there are some menus that i still don't know.

thanks again for your help.

i will give you the results of the test as soon as i do the next HD shoot.

Michael Nash · June 5, 2004

+++ if you know an internet site where i can get the user's manual for the camera (a .pdf file or something like that) it would be great because there are some menus that i still don't know.

http://www.cinematography.net/CINEFILE.HTM

nicolas Khoury · August 4, 2004

i have some bad news. it is not the DCC. by the way the distortion was not hapening in the highlight zones but in the midtone zone. i talked to the rental house and he said it is normal to the camera to do so. he said it is a bug in the camera and he said he contacted Sony and they said so. (i am not sure that he called them) i tried the camera with DCC off and i turned off all Knee options after having reset all the menus. i tried it again on the sky and it did the same thing.

Elhanan Matos · August 5, 2004

From what you described it sounds more like something happend to the DPR board in the camera, not a glitch. Which rental house did you rent your camera from?