DV Info Net - Low light setup on EX1 Help, please

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Quote:

Originally Posted by Alex Raskin (Post 970817)

Are you saying that EX1 derives 720p from 1080p by applying 6dB gain, then sizing down and blurring the image?

Exactly. The blurring must be done before downscaling to avoid aliasing (Nyquist–Shannon sampling theorem). So the high-frequency components of the (I guess white) noise are eliminated and so the noise-power gets lower. The sony-engineers decided to use that noise-drop to upgrade the light sensitivity by appling gain. So the ex1 has the same noise at all resolutions but different sensitivities.

Quote:

Originally Posted by Dominik Seibold (Post 970730)

I compared 1080p with 6db (not 0db) to 720p with 0db, but anyway...

720p with x db gain compared to 1080p with x db gain is one stop brighter.
720p with x db gain compared to 1080p with x+6 db gain has (about) one stop less noise.
Why? Because 720p with x db is 1080p with x+6 db low-pass-filtered (=blurred).
From this it follows that if you blur 1080p with x db accordingly, you'll get 720p with x-6 db.
If x<6, then it's not possibly to get that 720p-result in the camera, but only in post with 1080p-footage.

One conclusion is:
If there's enough light to film with 1080p with <6db gain and you want the lowest noise possible (and you don't need a framerate higher than 30fps), use 1080p instead of 720p.
That's also true for 1080i, because it's also derived from 1080p with 6db extra-gain.

This actually reflects my first tests with the Ex3. I compared all the different recording formats in the same light and using all the different gains. After it was all said and done, the winner in my eyes was always 1080p. Some of the others were brighter but you don't want a bright image, what you really want is to see details in low light. I could see more in the available light at 1080p than I could with noisey 720p or 1080i for that matter.

Quote:

Originally Posted by Dominik Seibold (Post 970920)

So the ex1 has the same noise at all resolutions but different sensitivities.

My point exactly. The camera is more sensitive for the same amount of noise by using 720P.

Quote:

Originally Posted by Alister Chapman (Post 970991)

The camera is more sensitive for the same amount of noise by using 720P.

Yes, but you're sacrificing resolution. I wouldn't recommend that.

Another example:
Imagine you have a noisy photo, and you want to print it. Would you really blur it before printing to reduce noise? Well, I wouldn't.

Depends on what you are doing. Excessive noise is a good way to get your programme to fail an HD broadcasters QA checks. Noise is the enemy of modern low bandwidth broadcasts.

Erik I loved the video

I really enjoyed the Halloween video. Would you be so kind as to share the settings with me for that light? I will enter them into my EX1 profiles.

Phil

Quote:

Originally Posted by Phil Hanna (Post 971379)

I really enjoyed the Halloween video. Would you be so kind as to share the settings with me for that light? I will enter them into my EX1 profiles.

Phil

Oh it was very simple. picture profile STD4, I pushed the gamma all the way to +99, black is +1, and black gamma was +5. Plus I always use 1080p and try to keep the gain no higher than +9 for night shots because it keeps the noise in check. If I need more than +9 gain I like to use the 2 frame slow shutter instead. Although you really have to pan and tilt slowly for that..

I am still playing with the black gamma, and black level but you can see in the video they don't look too bad.

Also have some night video in this with the same settings.

Dumont Dunes Halloween on Vimeo

I'm going to try and push black gamma even higher next time I go out, and then return it to +5 to do a side by side, see which one I like best.

You forgot to mention your knee-settings.

Quote:

Originally Posted by Dominik Seibold (Post 971789)

You forgot to mention your knee-settings.

I am still learning all this stuff, I haven't touched that yet. :) I guess I will go play with it.

just to put a finer point on it.. let's see one of the other cameras do this. :)

The Orion nebula. 16 frame slo shutter. A little post gain and offset adjustment. I'd love to try this with a lens that can do 50X or something. (open the photo and zoom in to see the nebula. Very hard to capture on video)