the double shutter speed rule ruins your video

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OP Svetlov Misha Forum Member • Posts: 78
Re: the double shutter speed rule ruins your video

why film, let's talk about digital cameras with global shutter i have it alot, you too, i think.

almost any digital photo camera has curtains - global shutter for photo mode, my camera records photographs for shutter speed 1/60 freely, no problem, all the lines of the picture is present in the frame, so, what is wrong about recording same picture with 1/60 movie mode? why the half of the picture lost?

how about 60p 1/120 - it still within flash's synchro speed?

why 120p 1/125 - perfect mode but 60p 1/125 - ugly?
why 60p 1/60 - ok mode but 30p 1/60 - ugly?

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John Brawley Contributing Member • Posts: 765
Re: the double shutter speed rule ruins your video
2

I don't think you understand how sensors work.

They have a scanning speed or integration time. Think of this as the clock speed.

This number is INDEPENDENT of the shutter speed you choose....

Here's a long thread on another forum where users have calculated the integration time for many popular cameras, using a technique you can replicate.

Most manufacturers don't publish their integration times, but it's not hard to work it out for yourself.

https://www.dvxuser.com/forum/hdslrs/hdslr-general-other/307186-measuring-rolling-shutter-put-a-number-on-this-issue#post307186

JB

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Andrew S10 Senior Member • Posts: 1,484
Re: the double shutter speed rule ruins your video
3

Thanks John, I actually posted the same link on the first page. The back and forth of this thread reminds me of the old proverb: you can lead a horse to water, but you can't make it drink.

John Brawley Contributing Member • Posts: 765
Re: the double shutter speed rule ruins your video
  • Andrew S10 wrote:

Thanks John, I actually posted the same link on the first page. The back and forth of this thread reminds me of the old proverb: you can lead a horse to water, but you can't make it drink.

Whoops  thanks for pointing that out.

I think he’s stuck on shutter speed BEING the integration time.

jb

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OP Svetlov Misha Forum Member • Posts: 78
Re: the double shutter speed rule ruins your video

John Brawley wrote:

This number is INDEPENDENT of the shutter speed you choose....

my experiment shows camera records more with equal shutter, almost every frame with all the picture versus the half of the picture if double shutter frames. it practice - disaprove it

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Entropy512 Veteran Member • Posts: 5,304
Re: the double shutter speed rule ruins your video
1

John Brawley wrote:

  • Andrew S10 wrote:

Thanks John, I actually posted the same link on the first page. The back and forth of this thread reminds me of the old proverb: you can lead a horse to water, but you can't make it drink.

Whoops thanks for pointing that out.

I think he’s stuck on shutter speed BEING the integration time.

jb

Nah, it's worse than that...  See the other thread which got locked...

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John Brawley Contributing Member • Posts: 765
Re: the double shutter speed rule ruins your video
1

Entropy512 wrote:

Nah, it's worse than that... See the other thread which got locked...

Wow.

I just saw that video he made.

He does't understand that the STROBE isn't SYNCRONISED to his sensor. Thus you get the rolling shutter interval / torn frames.

Also, Arri Alexa, the camera that's basically made every good looking feature film and television you're watching and is certainly NOT a consumer camera...also has a rolling shutter...it would have the same problem if he shot this ill conceived flash test.

(They did make the Alexa Studio which did have the same rolling shutter with an added mechanical shutter but it wasn't popular and they no longer make it)

Hint. The camera's integration speed can usually be worked out by doubling the cameras top video frame rate speed. It's basically the fastest the camera can clock the frames (shot at whatever shutter speed you choose) off the sensor.

Here's a suggestion for the OP.

Do the test again.

Use this light.

https://creamsource.com/product/vortex8/

Then use this adaptor.

https://accessories.creamsource.com/products/creamsource-flashbandit?_pos=1&_sid=8f0720c4e&_ss=r

This adaptor will take the SYNC of the camera that you plug into and make sure the FLASH or STROBE only happens when the frame interval is starting.

Presto. No more torn frames.

You can see what happens here. Unilux made strobes that SYNC to video cameras. You can see what happens in this clip.

https://www.labelsandlabeling.com/video/unilux-strobes-stop-blur

JB

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John Vickers Contributing Member • Posts: 583
Dorothy Parker
1

Andrew S10 wrote:

Thanks John, I actually posted the same link on the first page. The back and forth of this thread reminds me of the old proverb: you can lead a horse to water, but you can't make it drink.

Or, as Dorothy Parker put it:

Dorothy Parker said:

You can lead a horticulture but you can't make her think.

CanonUserG40
CanonUserG40 Regular Member • Posts: 196
Re: the double shutter speed rule ruins your video

This is a much more enlightening video about frame rates and shutter angles.

https://www.youtube.com/watch?v=UPPSdCrqcFQ

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OP Svetlov Misha Forum Member • Posts: 78
Re: the double shutter speed rule ruins your video

did you watch the vid you posted? it says my results. it confirms my experiment but can not explain it

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OP Svetlov Misha Forum Member • Posts: 78
Re: the double shutter speed rule ruins your video

you do not need to sync the flash with the frame beginning. its ok for me if the frame will be splitted in parts - unsynced, that is why i glue those parts together as a single frame. there are some frames totally synced and some of them not - does not matter. the thing is about those black hole inbetween frames, the less those hole - the better. those black hole i assume as lost picture, "not_recorded_info".

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John Brawley Contributing Member • Posts: 765
Re: the double shutter speed rule ruins your video
2

I'm guessing that English is not your first language so perhaps this is harder to translate.

24 FRAMES per second.

so, with a 180 degree shutter, HALF of the second, or 0.5 seconds is being exposed 24 times, the other half of the second is NOT being exposed.

Each single frame which takes IN TOTAL 1/48th of a second to be exposed, each line of a CMOS scan is built up. Yes. There is a temporal or time offset from the first line to the last line. So what happens in time at the top of the frame, might not be happening by the time the bottom line of the frame is being exposed. Which is why a strobe light like you used which is very brief is only existing for a part of the frame cycle.

In a global camera or a film camera, the ENTIRE frame is recorded concurrently, so there is no temporal or time offset between the first line and last line.

Then for 1/48th of a second nothing is being recorded.

Then it starts again.

Your video makes no sense and doesn't explain your claim that footage is somehow "ruined"

Exactly HOW is it ruined ? Be really really specific here because you aren't making a case.

If your evidence is so good, then why are you the ONLY person that thinks this. You're not making yourself understood.

Your experiment proves nothing and only confirms what I have said above. If the stobe is not synchronised to the shutter and you DO NOT know how many cycles / intervals it does over time then you can't really show anything. Your experiment is flawed.

JB

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John Vickers Contributing Member • Posts: 583
Re: the double shutter speed rule ruins your video
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You're wasting your time.

The OP is either a troll or a looney, or both.

OTOH, sometimes when an idiot asks a question, they can serve a purpose by making us think about the answer, even if they won't listen to that answer.

John Brawley Contributing Member • Posts: 765
Re: the double shutter speed rule ruins your video
1

John Vickers wrote:

You're wasting your time.

The OP is either a troll or a looney, or both.

OTOH, sometimes when an idiot asks a question, they can serve a purpose by making us think about the answer, even if they won't listen to that answer.

Thanks John.

It's always worth re-examining how you think things work.  But yes, there's a gap in understanding here for sure.

JB

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CanonUserG40
CanonUserG40 Regular Member • Posts: 196
Re: the double shutter speed rule ruins your video
2

It actually explains the relationship between frame rate, shutter speed, and motion blur. At no time does it state that it "ruins your video".

Your whole experiment is flawed, especially using a flash with such a short duration, and that you've actually stitched pictures together. Plus, of course, the nonsense about CMOS sensors.

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OP Svetlov Misha Forum Member • Posts: 78
Re: the double shutter speed rule ruins your video

John Brawley wrote:

24 FRAMES per second.

so, with a 180 degree shutter, HALF of the second, or 0.5 seconds is being exposed 24 times

to be clear... half of the sec contains 12 frames... are you sure you know what are you talking about?

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OP Svetlov Misha Forum Member • Posts: 78
Re: the double shutter speed rule ruins your video

impulse duration of the flash canon 430exII set to 1/64 is 1/10000 of a second.
it is short enough to illuminate the only one frame, isn't it? yes or no?
isn't it much shorter than shutter speed i choose? 1/30 or 1/60 or 1/120?

so, what is the phenomenon about NOT registering those flash on double_ruled_shutter speeds? i set equal fps/shutter speed = flash recorded, set double shutter speed - miserable part of the flash is registered, why?

is the reason of it in line-by-line sensor scan? is it not fast enough lining? but i may set shutter speed even shorter 1/120 with 120p and the flash will be perfectly recorded.
why shutter speed much shorter registers those single flash much better?

my assumption of the experiment is that the camera does not record information correctly, economizes, cheats. it's not about inter-frame compression, I used a camera with ALL-I compression and the frames got exactly the same. my assumption is that the camera does not write individual frames fully for some reason

ps. about the evidence strong or not...

first.. could anyone assume the evidence why i should to use those 180 film camera rule for digital camera, plz, no blablabla, just facts.

second... flesh is weak... nobody wants to admit their mistakes. digital cameras has nothing common with film ones but every single one bloggers must to claim: USE THOSE 180 FILM CAMERA RULE! ask them - why should i? what will they answer? - its historical, just shut up and obey

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John Brawley Contributing Member • Posts: 765
Re: the double shutter speed rule ruins your video
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Svetlov Misha wrote:

impulse duration of the flash canon 430exII set to 1/64 is 1/10000 of a second.
it is short enough to illuminate the only one frame, isn't it? yes or no?

No.

If indeed the strobe really is that short of a duration, then the FRAME is being assembled line by line as the strobe happens to fall somewhere in the interval while this is happening.

What you don't know is the interval between each strobe AND you have no way of synchronising it to the frame cycle.  So you're just looking at two cyclical events over time with no real way to correlate the two.

my assumption of the experiment is that the camera does not record information correctly, economizes, cheats. it's not about inter-frame compression, I used a camera with ALL-I compression and the frames got exactly the same. my assumption is that the camera does not write individual frames fully for some reason

but you're ignoring the fact that most cameras used in cinema and TV production work the same way.  So how is it that they are all ruining video ?  You say ruining video but I don't understand WHAT it is that is ruined even if we accept your theory.

ps. about the evidence strong or not...

Your evidence is wrong.  I've pointed out many times the RIGHT way to test what you're trying to test.   If you were serious about this you would test in the way I describe.  You evidence also backs up what I am saying.

first.. could anyone assume the evidence why i should to use those 180 film camera rule for digital camera, plz, no blablabla, just facts.

I have actually used strobes in the way I just described above and previously.  You have not.

I speak from a position of having done this.

Those are the facts I rely on when I post in response to you.  Instead you throw insults.

second... flesh is weak... nobody wants to admit their mistakes. digital cameras has nothing common with film ones but every single one bloggers must to claim: USE THOSE 180 FILM CAMERA RULE! ask them - why should i? what will they answer? - its historical, just shut up and obey

Most cameras work in exactly the same way.  Alexa, RED most Sony cameras are all CMOS line scanning sensors.  I'm not telling you to shut up. But I ask you one thing.

How is the footage "ruined".  Describe to me what is ruined. Exactly.  Precisely.  Don't link to a video.  Use words.

I still don't understand what's "ruined" here.

JB

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John Brawley Contributing Member • Posts: 765
Re: the double shutter speed rule ruins your video
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Svetlov Misha wrote:

John Brawley wrote:

24 FRAMES per second.

so, with a 180 degree shutter, HALF of the second, or 0.5 seconds is being exposed 24 times

to be clear... half of the sec contains 12 frames... are you sure you know what are you talking about?

Yes. Over the TIME interval of a second, half of the time the shutter is OPEN and lines are being recorded.

The other half of the second is dormant.

This in total. This happens in 1/48th intervals OVER a second.

Here is a break down of that over a single second...

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

1/48th - Shutter is open

1/48th - Shutter is closed

And then within each OPEN shutter cycle....

Shutter is open for 1/48th of a second...

1st line is recorded

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2nd line is recorded

----3rd line is recorded

------4th line is recorded

--------5th line is recorded

----------6th line is recorded

------------7th line is recorded

--------------8th line is recorded

----------------9th line is recorded

------------------10th line is recorded and so on depending on the resolution of the sensor.

Each line is recorded AT A DIFFERENT TIME within the single 1/48th of a second allocated to record that single frame. Each of the slightly different time recorded lines are assembled to make a single frame but the TOTAL TIME TAKEN to record that frame is still 1/48th of a second.

You flash might occur across lines 1- 4 in this case the first time and then in the same frame at lines 8-10 OR it might cross a frame boundary. You don't know because your strobe isn't starting at the same time and isn't synced to the frame count.

When you record at higher frame rates, the timing of when those lines are recorded CHANGES so the overlap of each strobe on those random lines will also change.

.. are you sure you know what are you talking about?

Are you?

JB

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Entropy512 Veteran Member • Posts: 5,304
Re: the double shutter speed rule ruins your video

John Brawley wrote:

Svetlov Misha wrote:

impulse duration of the flash canon 430exII set to 1/64 is 1/10000 of a second.
it is short enough to illuminate the only one frame, isn't it? yes or no?

No.

If indeed the strobe really is that short of a duration, then the FRAME is being assembled line by line as the strobe happens to fall somewhere in the interval while this is happening.

In fact, rapid pulsing of light with a known pulse duration is one method by which people measure readout times.  CineD uses a 300 Hz strobe for their lab tests

(Yes, Jim Kasson uses a classic analog oscilloscope for his tests, but not many people still have one of those lying around!)

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