unlike every other camera I have ever used when in 25p mode (not 30p) my shutter is 1/33 at it's normal slowest setting not 1/25. Why is this?

I noticed something similar in the "NTSC Area."

My guess is that Sony figured 1/25 is the same as "shutter off" and so did not bother to include the menu item.

Of course, for the classic 180° film look, 1/50 would be the shutter of choice, though I have long favored the 360° shutter (shutter off) that these progressive cameras offer as an improvement over the longstanding limitations of film.

I've been experimenting with the shutter recently too and noticed he same thing Phil. Turning the shutter off definitely does the trick though.

I'm not sure if it's just something I'm doing wrong but I'm finding that I have to play with the shutter speed a lot just to get rid off frequency induced rolling effects when shooting near any kind of electric light with this camera. Maybe this is only common in CMOS cameras as I've never noticed it before with the XH-A1.

Shooting indoors with an NTSC setting is for me impossible, I have to select a PAL frequency in order to have any chance of canceling out the effect.

Shooting indoors with an NTSC setting is for me impossible, I have to select a PAL frequency in order to have any chance of canceling out the effect.

I've noticed the same problem shooting 24p with the SI-2K. Iron ballasted fluro lights causes rolling bands. HF ballasted fluros and HMIs are fine. Shooting 25p is a perfectly valid solution. Depending on your NLE it can be pretty simple to slow 25p down to 24p losslessly when you strike lighting that you have no control over.

I am a little confused:
Is it now possible to switch to 1/50 shutter speed when shooting 25p or is it not? (Not having 1/50 for 25p would be a real drawback!)
Thanks for feedback in advance.

I am a little confused:
Is it now possible to switch to 1/50 shutter speed when shooting 25p or is it not?

Yes you can select 'Speed' mode and choose 50. I prefer to use the 'Angle' mode and dial in 180 degrees, which does the same thing but also changes with framerate, so if you overcrank or change framerate the shutter speed (exposure time) changes relatively.

Paul.

Thanks, Paul, good to hear that!

Thanks for the thread.

Paul, as I've never used "Angle" wouldja mind elaborating on "I prefer to use the 'Angle' mode and dial in 180 degrees, which does the same thing but also changes with framerate". Would really appreciate it.

Somewhere along the line I picked up that 1/48 was about the optimum and while it can't always be there and there are no absolutes, thats usually been my target.

- Ray

Hi Ray.

I don't think there are any hard and fast rules, but using a shutter speed twice that of the recording frame rate is a popular setting for trying to achieve film like footage. So using a shutter speed of 48 for 24p shooting means that your exposing each frame for half of it's available exposure period.

If however you increased your frame rate to 48p then to keep the shutter per frame at the same relationship you would also need to increase shutter to 96.

Using angle is something that has been passed down from film cameras where a rotating disk passes over each frame of the film. The 'angle' of the cutout area of the disk changes the amount of exposure each frame gets.

Obviously with an electronic shutter this isn't happening physically, but it allows you to apply a setting that will remain constant no matter how you vary the frame rate.

This is a good illustration of how shutter angles work in film cameras...

http://en.wikipedia.org/wiki/Shutter_angle

regards

Paul.

Paul,

Look at my short, "My Autumn's Done come", the first few shots suffer from the rolling band problem due to light frequency problems. I didn't really notice it until the edit which was annoying!

What about the special feature to "remove" this kind of blink problem in lights ?
You can select the frequency of the blink, and it adds a kind of filter for that frequency... I don't remember the name of this option.

Look at my short, "My Autumn's Done come", the first few shots suffer from the rolling band problem due to light frequency problems. I didn't really notice it until the edit which was annoying!

I did notice that Phil, it's a real shame that it's made it to your edit which is otherwise so nice. I've started reviewing all indoor footage now after the first take. I can just about see the effect in the LCD with the info turned off but so far the problem is not appearing with the shutter matching the frequency of the light so from now on I'm just going to use 50 when shooting with lights.

Do you know what settings you used for those shots?

One other thing I've noticed is that sometimes the rolling bars will appear in the LCD to begin with but then after some camera movement (at least that's how it feels) it will fade. I'm not really sure what could be causing that but it's certainly one of the things to be careful of when shooting under electric light.

Sebastien, the feature is called 'flicker reduction' and I didn't find it to be very effective, at least when trying to use 720/60 under lighting.

Were they fluorescent lights?
It's probably due to older low-frequency-ballast fixtures. Newer fixtures have a faster response time.

I see the effect with regular (non fluorescent) bulbs too. I think it's to do with the frequency of the power supply.

IMHO I don't find the rolling bands in the opening of Phil's DoneCome MASTERPIECE at all distracting (I barely noticed the effect in the first few viewings).

Simply put, 60Hz into 50Hz don't go (or vice-versa) hence the 'beat' effect.
This is a common problem to workaround with CCD cameras as well, just manifests as a slightly different effect (rolling bands i.s.o. pulsing)

This brings me to thinking about how well the EX1 could shoot a CRT screen (remember them?), providing the shutter matches the refresh is there any rolling (or other) artefact present that one would not expect from a CCD?

I have not see not seen this. I had a real concern since I shoot concert lighting. Most of my lights have MSD lamps. I have not checked out my LED panels with the EX1. These are the type of panels they use as backdrops on stages.
My other video cameras (HD100, global shutter) flicker when shooting these panels.
It mainly has to due the dimmer function with LEDs using PWM (Pulse Width Modulation). It's essentially a duty cycle for controlling light output.

The flicker can be reduced quite a bit by timing adjustments in the DMX control circuit for these LEDs, nonetheless, as we know, all video cameras can suffer from issues causing flicker.

It will be interesting to see how the EX1 works with these LED panels.

Hey Paul, thanks for the clarification, glad there was a reason to the assumptions I've been working under even though I don't remember the source!

Okay, in my thirst for knowledge, how does angle fit into this equation? As you said "which does the same thing but also changes with framerate", does that mean that in your example of "If however you increased your frame rate to 48p ... you would also need to increase shutter to 96." If I were using angle instead of 1/48 that it would do this automatically? If so, then in 24p, what would be my desired angle?

So much to learn!

- Ray

Raymond,

The angle setting sets up a relative rather than absolute shutter duration.

It's based on the film tradition of the shutter being a essentally a spinning pie chart, spun by a motor at a constant speed (the frame rate). Here's a good schematic on Wikipedia:

http://en.wikipedia.org/wiki/Image:Moviecam_schematic_animation.gif

(thanks to Anthony at IEBA Tech Thoughts for the link)

Film cameras can only open their shutters to expose film around half of the 1/24 seconds alloted to each frame (1/48 second) because the other 1/48 second is needed to move the film though the gate and register it for the next exposure.

Because a circle is 360° around, this half-pie opening is considered to be a 180° opening.

Since this is a mechanical constant in a film camera, speeding up a film camera to, say 48fps, (by spinning the motor twice as fast) will allow 1/2 of the time (1/96 second) for exposure and the other 1/96 second to "pull down" the film.

Likewise 60fps (achieved by spinning the motor faster still) creates a 1/120 second exposure and 1/120 second pulldown.

Most film cameras have variable shutters. To create a shutter opening that is 1/4 of the time alloted to each frame, one would need to close the pie opening down to 90°. At 24fps this would create an exposure of 1/96 second. At 48fps it would be 1/192 second and at 60 it would be 1/240 second.

The EX1 allows one the option to use this film paradigm to set the shutter duration. When set to 180°, the shutter will always be one half of the duration alloted to each frame. When set to 90° it will always be 1/4 of the duration. When you change the frame rate in the EX1 when in the shutter angle mode, the shutter duration will change proportionally.

Although not a perfect representation of motion, we have gotten used to the 180° shutter and its half-exposure, half-non-exposure ratio and associate it with a film look.

One thing that video cameras allow that film does not is the ability to open the shutter beyond 180°. Turning the shutter off on the EX1 creates the look of a 360° shutter, an impossibility in film. I think as we use this 360° shutter more and grow accustomed to the larger amount of motion blur, this will become a more desirable shutter setting.