tests of dynamic range with DVRack + comments

[Mike Brown]

Originally Posted by Ali Husain

- killer combination when paired with a merlin

Someone (maybe in the support sub-forum) claimed that the combination is wind-sensitive, owing to its low overall weight and low moment of inertia. Did you notice any issues along this line?

[Fergus Anderson]

Thanks Peter

I really love the look of the cine mode in 24p apart from the softness/lack of sharpness. If the sharpness setting at 0 or +1 would rectify that I would be really pleased!

Is anyone in a position to demo that (24p sharpness 0 v +1) and upload a clip?

Many thanks in advance
Fergus

[Stu Maschwitz]

Has anyone figured out if there's a way to lock/set the shutter in cine mode? All my lowish-lighting shooting with cine mode has resulted in 1/24 shutter, which ain't cinema.

-Stu

[Ali Husain]

Originally Posted by Stu Maschwitz

Has anyone figured out if there's a way to lock/set the shutter in cine mode? All my lowish-lighting shooting with cine mode has resulted in 1/24 shutter, which ain't cinema.

-Stu

hi stu,

welcome to these boards! loved your vfx work in day after tomorrow and pirates.

some people more clever than me in another post figured out that if you insert a mini-SD card in the camera and push the photo button half-way, the camera will show you the current shutter speed and aperture settings. if you can get the autoexposure system to set the aperture JUST below fully-open, you know the point at which gain is being added (1.5dB per tick).

someone else, i think barry green, suggested that when aimed at the white screen of his cell phone, the camera's autoexposure always selects 1/48th second shutter speed. and you can apparently lock-in the shutter speed by switching exposure to manual (pushing in the joystick button, then clicking up on "EXP," but you already know that part).

i imagine that a combination of using a known brightness calibrator and the shutter half-way button test could give you effectively full manual control, albeit at some inconvenience.

just a few more external controls on this camera and slightly more custom picture and gamma curve controls (and maybe a black body), and this camera would probably kill everything under $5k in the indie market.

[Povl H. Pedersen]

You can actually go to wide open. But you need to come from f/2.0 and then the next stop in exposure up, so it is the first exposure level with f/1.8. Then you also know there is no gain.

The guides are designed for Tv mode, with the lower dynamic range compared to CINE mode.

For cine mode, you can do the same.

Point at some light bright enough to give you the wanted shutter speed (half-press photo button with a miniSD car in the camcorder the see shutter/aperture). Outdoor, somewhere in direction of the sun can give you a faster shutter, or use another light source.

Press the stick, when it says EXP, push it up, and you are now in manual exposure control mode with a locked shutter speed, and exposure giving you control of aperture. First stop at f/1.8 is = no gain. If you continue adding exposure, beyond the first f/1.8 then the camera is using gain (digitally amplifying image and thus adding noise). You might be able to add the gain later youself, maybe the camera will do better. I do not know as I have not tested it yet.

There is one exemption. If you lock at say 1/500s, f/8+ or more, then the exposure wil actually slow down exposure as well. In PAL land, it seems like it will slow down shutter to 1/50s before opening the aperture.

Same if you lock at f/1.8 1/25s (indoor), and then decrease exposure, then it will start slow down shutter until it hits 1/50s before it it starts closing the aperture.

So Cine mode has a target shutter speed of 1/50s (PAL land). If it goes slower, it will be because f/1.8 is not fast enough, and you will get in-camera gain.

So you need to add more light to get 1/50s (or 1/60s in NTSC land). Or you just lock the shutter speed, and suffers from the gain, or manually adjusts the gain away by the exposure control and do the gain in your post processing. But it will be different, as the MPEG2 compression probably makes big dark areas into same color areas, but I do not know for sure. I have not tested it.

Tv mode is the best bet if you want shutter control, then you control aperture (and later gain) directly using the exposure control

[Noah Yuan-Vogel]

I just picked one of these cameras up and after a little testing, all the mentioned observations appear to be true. I dont know if anyone mentioned it but here is the exposure priority for different modes:

24p cine (min f8@1/360 | max f1.8@1/12)
1/360-1/48 -> f8-f1.8 ->1/48-1/24 -> gain 1 - 7 units -> 1/24-1/12

60i cine (min f8@1/360 | max f1.8@1/60)
1/360-1/250 -> f8-f5.6 -> 1/250-1/120 -> ??? 1-10 units -> f5.6-f1.8 -> 1/120-1/60 -> gain 1-7 units

Anyone please correct these if there are errors. I have no idea what those empty 10 exposure notches are about, anyone else know? I can't imagine it is gain...

anyway, overall this seems like a pretty good priority to me. It is nice that f1.8@1/120 is possible in 60i mode for the sake of turning 60i into 60p for slowmotion. And in my mind, 1/24 isnt a bad cine-like shutter if necessary. I would like a little more control over the shutter wide open in cine mode though. It would be nice to be able to shoot wide open and bring up the shutter to something like 1/100 for high action stuff without having to sacrifice cine curves or 24p, but it looks like if you really want to do that, youd have to sacrifice one or the other.

[Noah Yuan-Vogel]

Nevermind, I dont think those minimum numbers are right, there are lower exposure settings, it just wasnt bright enough in my room to access them. The rest is still right though I think.