Please allow greater than 180 deg shutter angle!

[sander kamp]

So my camera is being used by a Japanese client shooting 30fps but we are in a 50 Hz country. If we leave the shutter at 180 there will be flicker, if I set the shutter to 216 (1/50) the number turns red and nothing happens. The only way i can make it work is to put the camera in varispeed mode, the number is still red but it works and no flicker. But the client wants to record audio on the camera and in varispeed mode you can't!

Am i missing something or is it really so that you can't shoot NTSC in a PAL country without flicker and with audio?

[conrad gaunt]

set the shutter speed to 1/30th of a second, thats 360degree. Or am I missing something..

[sander kamp]

In normal speed mode you can do that but exposure won't actually change beyond 180 deg. The number will turn red, indicating that this mode is not supported.

[Miltos Pilalitos]

I just dialed-in the settings that you said and nothing turned red. I am in a PAL country too.

In 30fps i can choose any shutter angle from 9 deg. to 360.

Are you sure you know what you are doing? :-)

[Cail Young]

Something's not set correctly - the camera should be able to record up to 1/30 in 30fps - what mode is the shutter in? NORMAL, SYNCRO or RELATIVE?

Also, are you using OPEN GATE? You might need to disable it.

[conrad gaunt]

Red is an electronic sensor, if you want a "video look" you can set 1/30 shutter. Dont do it!!!

[sander kamp]

Something's not set correctly - the camera should be able to record up to 1/30 in 30fps - what mode is the shutter in? NORMAL, SYNCRO or RELATIVE?

Also, are you using OPEN GATE? You might need to disable it.

Really? In the manual it only says i can't do 360 degree shutter with OPEN GATE. Shutter is in 'relative' mode. I have to try some things and get back as soon as i can access the camera.

[David Birdy]

"Flicker" is a subject that is difficult to understand....I've had many discussions with very talented people that do not understand the concept and have argued their point with me until they were blue in the face!

This is my understanding:

When you see "flicker" it is associated with the sensor capturing the AC frequency of the light source. All sources of light that use AC current will have a "sweet" spot setting to not see the "flicker" You can usually find that sweet spot by adjusting the frame rate and or shutter. On cameras with electronic shutters, remember the shutter " restricts " the amount of light hitting the sensor, so it's very different than the way a mechanical shutter operates.

A rule of thumb is to match the frame rate to the AC frequency that is being used by AC light sources. When in the USA use 60 frames per second, in 50 hertz countries use 50 frames per second.

Florescent lighting will minimize the flicker effect.

Of course if you use "Gods" natural light, the sun, you will not have any flicker issues !

EDIT
Remember: The higher the frame rate the more light the sensor needs. If you restrict the shutter setting to the point that the camera can not make the selected frame rate the camera will use the frame rate as a priority and adjust the shutter speed accordingly.....and that's a good thing!


Dave

[sander kamp]

Well, i have disabled OPEN GATE and it seemes to work, the number turns yellow and i don't see flicker in the transferred footage. We set the camera back to how it was before though since that worked and i better do some more testing to be sure. One thing though: the manual is very confusing in this matter.

[Shane Kelly]

I think that there is an issue with using relative mode in the latest builds. Try using normal mode and dialing in the shutter speed in fractions of a second.

[Stuart English]

So my camera is being used by a Japanese client shooting 30fps but we are in a 50 Hz country. If we leave the shutter at 180 there will be flicker, if I set the shutter to 216 (1/50) the number turns red and nothing happens. The only way i can make it work is to put the camera in varispeed mode, the number is still red but it works and no flicker. But the client wants to record audio on the camera and in varispeed mode you can't!

Am i missing something or is it really so that you can't shoot NTSC in a PAL country without flicker and with audio?


Try setting the shutter MODE to Syncro, then adjust SPEED and SYNCRO settings to get a shutter speed that you want.

This way you can still record audio as you are not in Varipeed.

[Cail Young]

Well, i have disabled OPEN GATE and it seemes to work, the number turns yellow and i don't see flicker in the transferred footage.

My understanding of the way OPEN GATE works is that it double-scans the sensor, and displays the image when the shutter is closed on the monitors. This would set the maximum shutter time to half the framerate, or 180°.

Any comment from RED?

[Robert P. Hogue]

Also, are you running your lighting from a three-phase electrical source with filament-based lighting, fluorescent, or Arc lighting? If so, ensure that all your lighting is wired to the same phase, otherwise you will get a 60 degree offset, for example at 24fps you would want your shutter set to 1/180th or 48 degree shutter angle on 60Hz systems, or 1/150th or 57.6 degrees for 50Hz systems. If you want to avoid this problem, ensure that flicker-free ballasts are employed - Electricians employed on big budget location shoots know this problem, and install flicker-free ballasts. Here is the rule for shooting where lighting is wired to three phase systems:
frame rate * 360/Power frequency * 3
Power frequency North America and some parts of Japan= 60 Hz
Power frequency Europe and most of Asia = 50 Hz

[Brian Langeman]

I think the only reason you were having problems before is because you had OPEN GATE enabled. You've found it and fixed it now though it sounds.

[Stuart English]

My understanding of the way OPEN GATE works is that it double-scans the sensor.. (this).. would set the maximum shutter time to half the framerate, or 180°.

Any comment from RED?

The above is correct

[Rob van Gelder]

So if it double-scans, the effective max shutter angle is 180 degrees, making it effectively interlaced video, but the data transferred to the disk is still 25P (PAL project) , can we conclude that what you see in the viewfinder or LCD or HD-SDI output is NOT the same as on the disk.....???

In other words, the lower strobing or motion blur with Open Gate is not recorded as such, the raw date is still 25 fps progressive.

Is my understanding correct?

[Cail Young]

can we conclude that what you see in the viewfinder or LCD or HD-SDI output is NOT the same as on the disk.....???

Correct here, but it isn't "effectively" interlaced, you're viewing 50P (or 48P or 60P).

[sander kamp]

I think I understand now. BUT... This is from the build 17 manual:

Open Gate: lets the camera preview images at 48Hz (50Hz) update rate when operating in
23.98 or 24.00 fps (25 fps) Project Frame Rates. In record, all monitor path images will be
viewed at 48Hz, but recorded at 23.98 or 24.00 fps (viewed at 50Hz, recorded at 25 fps)

Note: Use Open Gate with caution. Due to the doubling of sensor frame rate relative to
capture rate the following operational restrictions should be noted.

- Open Gate is not available in Varispeed or Ramp modes.
- Open Gate is not available for 50.00 or 59.94 Project Frame Rates.
- Video Genlock may not be available when operating in Open Gate.
- 360-degree shutter is not available when operating in Open Gate.

I think I may be forgiven for being confused here. The manual doesn't mention at all that in 30fps the camera doesn't allow you greater then 180 degrees shutter angle when OPEN GATE is on. In fact, reading this I would think OPEN GATE doesn't work in 30fps mode.

Dear RED, can this be updated/improved?

[Stuart English]

I think I understand now. BUT... This is from the build 17 manual:

Open Gate: lets the camera view images at 48Hz (50Hz) update rate when operating in
23.98 or 24.00 fps (25 fps) Project Frame Rates. In record, all monitor path images will be
viewed at 48Hz, but recorded at 23.98 or 24.00 fps (viewed at 50Hz, recorded at 25 fps)

Note: Use Open Gate with caution. Due to the doubling of sensor frame rate relative to
capture rate the following operational restrictions should be noted.

- Open Gate is not available in Varispeed or Ramp modes.
- Open Gate is not available for 50.00 or 59.94 Project Frame Rates.
- Video Genlock may not be available when operating in Open Gate.
- 360-degree shutter is not available when operating in Open Gate.

I think I may be forgiven for being confused here. The manual doesn't mention at all that in 30fps the camera doesn't allow you greater then 180 degrees shutter angle when OPEN GATE is on. In fact, reading this I would think OPEN GATE doesn't work in 30fps mode.

Dear RED, can this be updated/improved?

O.K how about this ....

Open Gate: lets the camera preview images at 48Hz or 50Hz or 60 Hz update rate when previewing or recording 23.98 / 24.00 fps or 25 fps or 29.97 fps Project Frame Rates.

In preview and record, all monitor path images will be viewed at 48Hz if recording is at 23.98 or 24.00 fps, all monitor path images will be viewed at 50Hz if recording is at 25.00 fps and all monitor path images will be viewed at 60Hz if recording is at 29.97 fps

Note: Use Open Gate with caution. Due to the doubling of sensor frame rate relative to capture rate the following operational restrictions should be noted.

- Open Gate is not available in Varispeed or Ramp modes.
- Open Gate is not available for 50.00 or 59.94 Project Frame Rates.
- Video Genlock may not be available when operating in Open Gate.
- Maximum shutter value when operating in Open Gate is one half the frame time (i.e 180 degrees)

[sander kamp]

That was fast response!

So yes, if this is correct than please change the manual in that way. Also, in the 'shutter' section there is no mention that OPEN GATE has influence on the available shutter speeds, maybe it should be mentioned there too. Otherwise you have to post on reduser (thanks guys!) or read the entire manual until you reach OPEN GATE.

Would it be possible to have the camera turn OPEN GATE off automatically once you go beyond 180 degrees? If I understand correctly this is already what is happening if you go in VARISPEED mode. I would think getting the correct shutter speed is more important than maintaining OPEN GATE.

[David Mullen ASC]

So what exactly is the point of Open Gate? What do you mean by "Preview" since you normally can see what the camera is shooting with the monitor-out?

[Stuart English]

Would it be possible to have the camera turn OPEN GATE off automatically once you go beyond 180 degrees? If I understand correctly this is already what is happening if you go in VARISPEED mode. I would think getting the correct shutter speed is more important than maintaining OPEN GATE.

That's always a dilemma, whether to do such things or not. At the moment we decided to leave it to the operator.

There should be feedback via the GUI however.

For example, lets assume you have selected 24 degrees (the value is reported in white text in the GUI) and then you enable Open Gate (now the value is reported in red text)

[Stuart English]

So what exactly is the point of Open Gate?

It lets you rehearse shots and set focus at a higher frame rate than you would normally get if you were to observe a native 24 fps / 25 fps / 30 fps signal.

The sensor runs at 2x that rate so we can see 48 fps / 50 fps / 60 fps. The recording system drops every other frame so we still record 24 fps / 25 fps / 30 fps/


What do you mean by "Preview" since you normally can see what the camera is shooting with the monitor-out?

I only use that term to differentiate between preview / record and playback as Open Gate is disabled on playback.

[sander kamp]

That's always a dilemma, whether to do such things or not. At the moment we decided to leave it to the operator.

There should be feedback via the GUI however.

For example, lets assume you have selected 24 degrees (the value is reported in white text in the GUI) and then you enable Open Gate (now the value is reported in red text)

Isn't that what is already happening when you dial in a greater than 180 degrees shutter speed? My point is that it was never clear to me what the reason was the number turned red. I just assumed the camera couldn't do it. The strange thing is, in VARISPEED mode the number is red as well but somehow it does work - probably because OPEN GATE is automatically turned off but the GUI isn't aware of it.

[J. Eric Camp]

Part of the number turning red is:

In "Normal" mode the shutter exposure time is determined by the shutter speed setting, independent of the frame rate. So in normal mode at a 24fps 180º shutter you are setting it to a 1/48th of a second exposure per frame. Well, when you enter varispeed, and crank it up to 72fps the camera is trying to maintain a 1/48th of a second exposure time but it can't because it is impossible.

That is why it turns red.