If I set my GH2 shutter speed to "4", how many frames per second is it recording at?

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Filmkid2003

Well-known member
If I set my GH2 shutter speed to "4", how many frames per second is it recording at?

Howdy y'all. If I set my GH2 shutter speed to "4", how many frames per second is it recording? Two frames per second? I want to record some nice timelapse footage without using an intervalometer. My guess is I just halve the shutter speed number and that will tell me how many frames per second are being recorded since a shutter speed of "50" records approximately 24 frames per second? Thanks.
 
I don't think you can set the shutter to 4 and the lever to burst.
When the lever is set to burst the lowest you can go is to 1/40.
If you shoot in a single shot mode you might get 2 shot per second at 1/4 speed.
 
It will always be "recording" 24 frames per second (in 1080/24 mode). But the chip can only generate unique frames based on the shutter speed -- if you have a 1/2 second shutter speed, then the most unique frames it can generate is two frames per second (each one imaged for 1/2 second). But it will record each of those frames 12 times.
 
Aaaaah. Gotcha. So, that's why the shutter speed goes all the way down to "2" but, what that "2" means is 24 frames per second but, its only 2 different frames recorded 12 times a second, right?
 
Filmkid2003 said:
Aaaaah. Gotcha. So, that's why the shutter speed goes all the way down to "2" but, what that "2" means is 24 frames per second but, its only 2 different frames recorded 12 times a second, right?
Click to expand...
Barry_Green said:
Yep.
Click to expand...

What? Do you really mean to say that a shutter speed of 2 means you're recording at 24 fps? The one has nothing to do with the other as far as I know. . .
 
hsitz said:
What? Do you really mean to say that a shutter speed of 2 means you're recording at 24 fps? The one has nothing to do with the other as far as I know. . .
Click to expand...

In 24p mode you are always recording at 24 fps. If the shutter speed is less then 1/24 then your effective frame rate will be less (the effective frame being the number of unique images captured per second). At 1/2 second shutter speed in 24p mode you will get 12 frames of image A and 12 frames of image B every second.

Also note that if you use full manual mode in 24p with manual focus you can go less then 1/2 shutter speed, I think.
 
The recording format will record 24 frames, regardless of what the shutter speed is. There will be 24 frames in the recording.

The shutter speed limits how many DISTINCT and UNIQUE frames can be created. You cannot have more distinct frames than the shutter speed allows. With a 1/2-second shutter, you can create no more than two distinct frames per second. With a 1/4-second shutter you can create no more than four distinct frames per second. So, the system will duplicate those frames in the recording. At 1/4-second exposure, you will get four distinct frames, each one recorded six times (six duplicate frames).
 
Umm... that's not how my GH1 does things when it records the stream. When I made my 1/2 second shutter film 'A Kindling Light' (in my sig link) I assumed it would behave as Barry describes but discovered that the stream in the .mts file only contained 2 actual frames per second and it played back as undercranked when transcoded so I had to slow down the footage to 8% to get 'real-time'. Playback in camera is real-time though.
 
Martti Ekstrand said:
Umm... that's not how my GH1 does things when it records the stream. When I made my 1/2 second shutter film 'A Kindling Light' (in my sig link) I assumed it would behave as Barry describes but discovered that the stream in the .mts file only contained 2 actual frames per second and it played back as undercranked when transcoded so I had to slow down the footage to 8% to get 'real-time'. Playback in camera is real-time though.
Click to expand...

Martti, GH2 is different in this respect. It works as described above.
 
Barry_Green said:
The recording format will record 24 frames, regardless of what the shutter speed is. There will be 24 frames in the recording.

The shutter speed limits how many DISTINCT and UNIQUE frames can be created. You cannot have more distinct frames than the shutter speed allows. With a 1/2-second shutter, you can create no more than two distinct frames per second. With a 1/4-second shutter you can create no more than four distinct frames per second. So, the system will duplicate those frames in the recording. At 1/4-second exposure, you will get four distinct frames, each one recorded six times (six duplicate frames).
Click to expand...

So I undertand this correctly I've simplified things:
At 1 second shutter you could have 1 distinct frame per second.
At 24 FPS each frame could capture 24 distinct frames per second.

Given what you described above I don't understand what happens. I see two choices:
1. The GH2 will take 1 'picture' per second at a 1 sec exposure (at 1 second shutter) then 'backfill' that single frame into all 24 available 'slots'; OR

2. The GH2 will take 1 'picture' per second at a 1/24 sec exposure (at 1 second shutter) then duplicate that single frame into all 24 available 'slots'

Is one of these correct?
 
If you set the exposure to 1 second, then the GH2 has to hold its shutter open for a full second until the exposure is complete. Once the exposure is complete, the camera sends that frame out to the recorder and starts exposing the next frame.

The recording media is cranking along at 24fps though. So it will just keep recording the same old frame over and over and over until the camera gives it a new frame.

At 1/24 exposure, the camera can generate frames fast enough that the recording system gets fed a new and unique frame every time it asks for one. At 1/12 exposure, the sensor is creating new frames only half as frequently as the recording media wants them, so the last frame stays in the buffer and the recording media ends up recording each frame twice.
 
Barry_Green said:
If you set the exposure to 1 second, then the GH2 has to hold its shutter open for a full second until the exposure is complete. Once the exposure is complete, the camera sends that frame out to the recorder and starts exposing the next frame.

The recording media is cranking along at 24fps though. So it will just keep recording the same old frame over and over and over until the camera gives it a new frame.

At 1/24 exposure, the camera can generate frames fast enough that the recording system gets fed a new and unique frame every time it asks for one. At 1/12 exposure, the sensor is creating new frames only half as frequently as the recording media wants them, so the last frame stays in the buffer and the recording media ends up recording each frame twice.
Click to expand...

Thanks for that, Barry, but this still isn’t clear to me.

Let me pose an example to clarify my confusion…
Let’s say I have a stopwatch that, instead of showing time in 100ths of a second it shows time in 24ths of a second. It displays them as 1/24, 2/34, 3/24 thru 24/24.
Also I’ve connected my GH1 to the trigger of the stopwatch so that it starts the instant the stopwatch starts, then stops after exactly 1 second.
I have set my camera to 1second exposure, 24 fps.
I hit GO

What is the output? Do I see:
1. 24 frames that all say 1/24, or
2. 24 Frames that show 1/24 thru 24/24 overlayed on each other, or
3. Frame one has 1/24, frame two has 1/24 overlayed with 2/34, frame three has 1/24 thru 3/24 overlayed.. etc, or
4. Something else?
 
iHartVideo said:
Let me pose an example to clarify my confusion…
Let’s say I have a stopwatch that... shows time in 24ths of a second. It displays them as 1/24, 2/34, 3/24 thru 24/24.
I have set my camera to 1 second exposure, 24 fps.
What is the output?
Click to expand...
* The first 24 frames will show the same image: the numbers 1/24 through 24/24 superimposed in order on top of each other.

* The next 24 frames will show the same image: the numbers 25/24 through 48/24 superimposed in order on top of each other.

* And so on...

Conceptually, what's recorded in the AVCHD file is a single frame with a one-second exposure time, followed by 23 empty frames that indicate that no visible changes have occurred in the image since the previous frame. In practice, the AVCHD encoder will also record key frames at a fixed rate set by the GOP-size. Each of these key frames will typically be a duplicate of the last recorded frame.
 
lpowell said:
Conceptually, what's recorded in the AVCHD file is a single frame with a one-second exposure time, followed by 23 empty frames that indicate that no visible changes have occurred in the image since the previous frame. In practice, the AVCHD encoder will also record key frames at a fixed rate set by the GOP-size. Each of these key frames will typically be a duplicate of the last recorded frame.
Click to expand...

Ahhhhh.... that makes perfect sense. Thanks for clearing that up.
 
Whats the slowest possible shutter speed for video ? Is it really 1/2 like in video mode or can it be lower when you choose the manual mode for images where you can dial down to bulb, but still capturing video ? I did play around a bit with very slow settings i.e. 1/30 but wasnt sure what the camera is doing actually, saw not much difference to 1/2 but maybe Iam wrong.
 
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