ISO rating

Arni Heimir · February 7, 2006

Is the ISO/ASA rating of the Arri D-20 fixed at 400? Is it possible to push the gain levels like with the Genesis to 1600?

Also, regarding color temperture: Is it possible to switch between 3200K and 5600K?

Arni Heimir

Iceland

Chris Clarke · March 26, 2006

A late reply....

I'm working as an assistant at the moment on an Arri D20 job. We shot exposure tests last week to determine the camera's ASA rating. We are using it in the 'Video' mode and have access to LUT's that replicate different ASA ratings. We have stuck with LUT #7 which equates to 320 ASA. The Astro monitor with the built in waveform is incredibly useful. The layout of the screen really helps with intepretating what's happening in terms of exposure. I think it also allows the DP to trust their meter more and treat the D20 as another 'stock'.

Last year I did some dailies on Flyboys with the Genesis. I only saw it set up for daylight. I believe Panavision rated it at 600 ASA but the cameraman was exposing it at 400 ASA. I never saw it in use in tungsten mode, but I know they rated it differently when switched over.

Hope this helps.

Annie Wengenroth · March 30, 2006

I am about to embark on my second job as an AC with the D20 this weekend. A couple weeks ago we shot some stuff using mainly the 6 and 7 settings (I can't recall what user setting 6 is but 7 is about 320, like Chris was saying) as well as the flat gamma setting. This time around the DP wants to go for higher contrast, so I'll report back as to what we end up doing.

As far as color temperatures, yes it is possible to switch. From what I can call, I thiiiink (I'll find out tomorrow) you can customize your gamma curve settings and then using the "service" port, back them up onto external hard drive? I will check up on it.

I am learning more about the camera as time goes by because I work at Arri CSC, so I talk to Andreas Weebler a lot. If anyone has any specific questions, I'll see if I can forward them to him; he is extremely knowledgeable. It has definitely been amazing to see the birth of the D20 technology and to be a part of it!

Chris Clarke · March 30, 2006

More D20 info.

Our DP has found that he's not getting enough exposure in the blacks when using User 7. User 6 is 160 ASA and Gamma 2.2 is 64 ASA. On exteriors we are shooting 2.2, going to user 6 if the light drops. If we get to the stage where 160 ASA isn't enough we call it a day. He's decided that user 7 is not doing it for him at the moment. It would be nice if we could change the names of these settings as 'user 6' and 'gamma 2.2' are quite cumbersome for constant useage on boards, camera sheets and in conversation.

Another interesting point is shooting in 4:4:4 HQ. We couldn't find a post house in London who could handle our rushes right through the post chain at this quality level. We are now testing shooting at 4:4:4 SQ or even 4:2:2.

In terms of colour balancing, we set it to 3200K or 5600K to suit the lighting conditions. Then with each lens change we white balance through any filters that are in place. This takes out any possible variables in lens and filters (not fx filters obviously) but also serves as a good routine to keep on top of light changes throughout the day. The white balance bizarely doesn't require any white reference card in the frame? It takes an average from the scene it's looking at. You need the camera to be close to the shooting stop though. Only once have we had trouble with white balance - we were on an underwater head with the lens 10" off the water looking at a tree line on a lake. Everytime we white balanced we got a heavy green cast across the image. We eventually solved it by holding my clapper board acoss a part of the frame to give it a little bit of white. Seemed to do the trick.

A useful thing we did, as we don't have flash mags here yet, was to velcro the control panel to the side of the camera body and run a long cable in the loom back to the SRW1 recorder. This allows the focus puller to control the turnover and also makes identing takes and checking timecodes a whole lot easier for me!

The on/off switch is in a stupid place, on the front under the shutter. When we have an LCS motor rigged for the iris we can't get to the switch! It should be on the back of the body under the power cable socket, like an Arricam ST.

I think they should also switch to the Arricam handle so you have a 3/8" thread on the front for mounting motors.

The Astro onboard monitor needs a rethink. There are too many exposed controls for assigning the information you can view on the monitor. They should be in a deep menu or under an access panel as in the morning when we pull the monitor out of its case they all get moved. We plug the camera up and can't get any picture! Then we're on the phone to the engineer going through the menus to reset the bloody thing. Having said that, once it's up and running it really is very good. In 'Studio' mode we mount it on the camera, but when things are getting nasty (rain etc.) we send it back to the monitor where the DP can use it as a waveform.

The back of the body needs a protective cover to stop the operator knocking things, especially if he's cradling it for a handheld shot.

The optical look through is a really nice touch for an HD camera. A strange thing though... when you cut the camera the mirror parks in the open position so when you look through you can't see anything! You can phase it back but it's annoying. Of course this also mean that you can't see anything until you power up which kinds of defeats some of the benefits of having an optical look through. Also when you take the lens off, the chip is exposed because of this. It needs a software update to cure this and maybe a dust check button. To see an image on the monitors the shutter has to be turning. You completely forget it's running and when you remove a lens you get a real fright to see the shutter spinning. And, when you look through the eyepiece - keep thinking we've blown a 1000'!!

Overall a fantastic camera though. Lots of little quibbles but it's definitely heading in the right direction. Me and the focus puller have enjoyed our week with it and learnt an awful lot.

And, beautiful images!

Stuart Brereton · March 30, 2006

Great info, Chris.

One point about the white balancing. If the camera "averages out" the scene, then surely in order to maintain a WB setting from lens to lens you would have to line up exactly the same frame each time. Without a constant reference for each balance (a white card) surely it is impossible to get a consistent setting

Chris Clarke · March 30, 2006

In truth, I don't know how it does it. I did ask and was told 'not to ask'!

Although the tech at Arri's was quite surprised when I explained to him our little hiccup. Maybe now I can ask :)

Stuart Brereton · March 30, 2006

Auto Tracking White and various other versions of the "Auto White Balance" have been around for a while. It's just not something that I would have expected to see on the D20...

Annie Wengenroth · March 31, 2006

Funny you mention the on/off switch, I noticed the same thing during checkout today; it really is in a weird place. At any rate we're bound for Connecticut tomorrow am for a 3-day shoot with this camera...I shall report back!