rolling shutter
 

is there any mode (1080 60i, 1080 30p, 720 60p, etc.) in the ex1 that decreases or eliminates the camera flash problem

No.



..........

24p with shutter off (either 1080 or 720) reduces the probability of the partial exposure, but the probability is still pretty good that it will happen.

i saw someone post a test, shooting flash into the camera and it was horrible. i mean ive done lots of weddings where the photographer shot 30 pictures (with flas) in less then 1 minutes during major moments like the first dance. how do you deal with something like that. im sure the client would say "theres something wrong with my video."

I think as far as the client is concerned the problem is a general one. In fact there is no problem really as you cannot be responsible for other people's flash guns. When you see a press conference on the TV often the screen is solid flashes and picture disturbance. I don't think there an be a negative because other more expensive cameras such as Red (as reported elsewhere) will react in a similar way because of the CMOS chips.

first off that video was slowed down so it looked worse. Is was shot 60fps. Yes it looks horrible. The only way round it is cover the whole frame with a flash using a plug in from red giant, a bit of a pain but works a treat

phillip have you used the red giant plug in first hand, if so do happen to have a sample of before /after or do you know of anyone that posted a sample with that experiment.

PS-phillip i love your work, very talented.
im just concerned that the ex1 is not a suitable camera for weddings being that most weddings are under low light ambience forcing the photographers to cponstanly use flash

It may not be suitable. If you're concerned, you might look the other way.

As Philip mentioned, it's not that hard to replace the frame in post.
Also, not all flashes will cause partial exposure. It depends on the strength of the flash and conditions. I've shot stage footage with the EX1 where there was almost non-stop camera flashes. There were no partial exposures. Now, if one of them turned and aimed their camera at mine, it would of been an issue.

But replacing a few frames is no big deal, IMO.
Especially, with the amount of other stuff I'm working on in post.

Yes but RED is not being marketed to the wedding crowd and I doubt anybody will use one for that. I really think the EX1 is the wrong camera for weddings. For that I would get a camera like the HD110 or even the XL-H1. It also helps they are shoulder cameras.
The client would complain if his video would look choppy and he has the right to do so. This is not a normal or acceptable thing. It would only happen because of the camera's fault and he doesn't care what camera you use, he only wants a nice video, which is what he hired you to do. If you use a camera that can't handled what is being shot it becomes your fault.

There's trade-offs on those cameras too..
As a JVC owner, the HD110 is not that sensitive under low light conditions.

I believe your correct that the EX1 is not ideal for weddings.

If there are a lot of flashes that caused an issue, it would take extra time replacing those frames.

OTOH, it may be worth it for the low noise 1080P image.

Has anyone tried the new Sony Clip software that is supposed to get rid of the banding from the flashes?

Thanks

Ronnie Martin
dirtracingvideo.com

Just a quick note but I'm just looking at some footage I shot back in November which was taken at night. I was shooting 720p at 1/25 (I needed all the light I could get) and just spotted that the nearby press photographer was using his flash and was not causing any banding whatsoever.

Clip browser will in remove the vast majority of flash bands from interlaced footage. It does not work with progressive material. Shooting 24P or 25P with no shutter will greatly reduce the instances of Flash bands, but not eliminate them all together.

What exactally is a Rolling shutter? there is no mechanical shutter in front of the cmos chip is there? And the Problems is a "Progressive" (of all words to use) Slow scan and reset of the photon imager chip things right? (that is what the technical analisis said)

so there is nothing rolling, and there is no actual shutter, its a electronic progressive slow scan of the chip? How did this Web word end up getting applied one time to this and it end up with some dark ages film words, when at the same locations people geekspeak with 75 technical Abbreviations , and everyone knows what they are talking about.

Because it is also slow scanned when making an interlace signal, we could create a new abbreviation, that is better suited to the reality of what is occurring.

Progressive Interlace Slow Scanning Cmos Reset And Proceed
ok mabey that wouldnt be a good abbreviation :-) try just PSS for the short abbreviation

Then when a Customer asks why the camera has a problem , you just tell them it has a bad case of PSS.


Does the Clip Browsers "Fixing" require that the now encoded video get de-re-compressed to be able to work with the magic Long GOP compression and manipulate the internal frames?

How about ' Progressive Motion Technology' -- or 'PMT' for short?

OK, maybe not !! :-)

It does seem as if those who have stuck with CCDs for wedding videography seem happier! -- I think I would consider the Panasonic AG HMC150 for that kind of work.

Reasonable low light images, and absolutely no 'flash banding'.

It's called a rolling shutter because in effect the imager scan continuously rolls to the top of the sensor at the end of each scan and then rolls down the sensor to the bottom before repeating the process again. The sensor is constantly being scanned. It has nothing to do with progressive or interlace.

In a wedding video that's thoughtfully shot, with good audio and great moments from that most important day, I wonder how many bridal couples will even notice the partial-frame flashes?

I realise that it has nothing to do with a "progressive" picture itself. but look a that word itself as it is used, it does little to describe the differences of video progressive and interlace itself.

progressive
1. Moving forward; advancing.
2. Proceeding in steps; continuing steadily by increments

That doesnt speak english of a "Full Frame of video captured in one pass" at all.
But it has caused about 1 Million questions as to what the differences are between progressive and interlace. Many people still not understanding the differences, or the advantages interlace once had.
Interlace or Interleaved Feilds, is easily a correct wording for the other,and easily explained.
Do they have a word for that in Japan, that didnt translate?

the chip IS scanned progressivly (its in the book), the progressive picture isnt progressive , it is bad form of Videnglish that only serves to confuse. There is no shutter, and the rolling is a progressive scan by techincal definition.
I am just saying the "techwords" that we have adopted are not helpfull at all, they instead confuse. then reading 30 pages of techjunk we get the real meaning.
Still have to exsplain it to the customer if they have questions or what to know why things look the way they do.

Which brings up one more important thing.
Is an Interlaced full frame from a CMOS captured in 2passes, captured interlaced out of 1/2 the lines (because it can be scanned and reset that way), or interpreted out of something after capture.
WHY?
because interlace on the CMOS HAS 2 seperated feilds that both have different feilds of motion. (real true 60feilds from different times)
BUT
interlace or progressive , the sensitivity of the collection , or low light capability, doesnt seem to change? (diode exposure time)
IF
you shoot in 60i or 30P , it doesnt seem to change the exposure capability of the camera. knowing stuff like that, could be usefull for choosing IorP from a cmos when working in lower light, or when worrying about Skew problems.

yesterday, on the David letterman show, they made some techspeek video geeks look like clowns for a skit, sort of shows that we will be keeping our jobs, no regular human could understand a word/abbrev. they said :-)

My guess is that the sensitivity doesn't change because each single displayed field line is made up of the sum of two scan lines. The summing of overlapping line pairs is done to prevent line twitter and is normal practice in interlace for both CCD and CMOS cameras.

Field 1:===================Field 2:

Display Line1 = sensor scan line 1+2

========================Display Line 2 = sensor scan line 2+3

Display line3 = sensor scan line 3+4

========================Display Line 4 = sensor scan line 4+5

Display line 5 = sensor scan line 5+6

and so on.....

The sensor must be scanned twice (as you would expect) for each interlace frame as flash artifacts normally only appear in one field and not the other.

I agree that the use of jargon gets crazy sometimes, however I do see some logic and meaning in the use of the word progressive to differentiate the whole frame scan from the 2 x interlaced field scan. As in your quotes, progressive scan moves steadily in the same direction until the entire frame is scanned, whereas the interlaced scan has to jump back almost to the start when it gets halfway through the frame.

Richard

but the confusion comes in when , if it was being scanned 2 times for 2 different Interlace Feilds in 60i, then the rate/speed of the whole chip being scanned is minimum ~60fps.
then combined to make the single 30fps interlace FRAME.

When it is in progressive the chip only has-to be scanned at ~30Fps , to make the single 30fps progressive frame.

That would provide for 2times the photo diode exposure time, aka 2 times the low-light capability. Scanning at 60 vrses scanning at 30, reguardless of the final frame assembly.

we can sort of SEE that there is something different IN the scan rates , they cant both be ~60fps because we can alter the "shutter" in 30 , which sets the cmos exposure time right? We can set all kinds of "shutter" speeds in the camera for 30P 30 40 50 60.
plus we can observe that it does have 2 feilds in the interlace at 60i.

So why IF the chip is being scanned at ~60 (for interlace) Vrses ~30 is there no chip sensitivity differences?

This comes from many thing i have read, not fitting together in total "logic" when you assemble them, then test the camera itself.
Plus my CCD cameras did increase huge in light sensitivity when the 60i signal was shuttered to a (still interlace output) 30fps , for those it may have been frame doubling post processing not chip exposure time. We cant have frame doubling here being a factor, if we have motion between the 2 feilds still, and the Sqew ammount changes with the scan rate, and the chip is scanned "rolling".

Side notes: A analisis of these cameras that also did not make sence, indicated that at 24fps , the "sqew" ammount reflected a scan rate of the chip from top to bottom at 60fps.
How can the camera have 24fps motion blur, 24fps frame judder, ability to set a shutter speed below 60fps that changes the picture, AND still have a squew that reflects only 1/60th of a second.
it is a virtual impossibility, in my mind, but i have an idea how they may have assumed that, based on output they view, or else the device is working different than they are saying.

* all of this discludes the idea that my brain doesnt function normally, :-) or there is a missing piece of information.

Did you not read my previous post?

Because in interlace for each single line displayed, 2 lines are summed, ie added together, thus the signal from one pixel is added to the signal from the pixel below which gives TWICE the signal, thus twice as much sensitivity. So if you have twice as much sensitivity but only half the exposure you get the same sensitivity as an exposure with half the sensitivity but twice the exposure.

The scan speed is simply the rate at which the readout cycles from top to bottom of the sensor. You slow the frame rate by adding a delay or pause between the start of the each scan sequence. So if the scan rate is 1/60th and you shoot at 24P (1/24th) the delay period is 1/40th of a second. So that means you have a period of 1/40th of a second where the sensor is not being scanned but is gathering light and this is why you get less flash band issues at slower shutter speeds and frame rates.

Fast shutter speeds are achieved by reseting the sensor rows to zero in time with the sensor scan such that the time (integration period) between each row being reset and then scanned is equal to the shutter speed. Hence the shutter roll as you get a narrow band of active pixels rolling down the sensor when using a fast shutter. This is why flash banding is worse at higher shutter speeds.

line summing also doesnt make sence to me.

they claim the resolution drop from 30-60 is from 900-700 , and i have interlace full frame pictures here that dont seem to be slapping together lines, at least not as badly as thier picture showed, with all the "twitering" and jaggies and such.

http://home.comcast.net/~TVV0/MiniStage.jpg <--- that is interlace, it has not been de-interlaced.
zoom up to 200% and it doesnt look neer as bad as the pictures they were showing of the EX1, where they showed obvious issues with the interlace lines, thier picture however it was done, did show that some nasty stuff was going on in the interlace , this picture is Post compression besides.
On the Blue toys RED nose, i can see a completly wacked out line there.

i should probably get a solid picture of Both 60i and 30p of the exact same thing, and see what i am missing.

now i see
Scene30Pvs60ion toplayer.psd
(8megs Psd layered compatability file)
this is an adobe photoshop with the Top layer being 60 interlace (not de-interlaced)
it is closly matched to the other picture, being 30p below it.
In "layers" window in photoshop, a person can unView the top layer and see the differences.
Switching the layer to diference will also show differences, although it is not aligned that well, and there is many compression artifacts.

What i noticed so far. in interlace
Red seems to have the biggest issues
is all a bit muddy
the kool aid thing basically goes to heck all over it
loose lines of color hoping off the color
resolution on the furry stuff goes muddy
the color box edges hold mostly with the red going wackey
the artifact noise is different, slightly less
full black to white edges look similar