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combatentropy

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Yet Another Rolling Shutter Post.

Jim Jannard and Co.,

Why no forecast of a global CMOS shutter?

These companies have shown that global-shutter CMOS is possible:

- Micron
- Awaiba
- Altasens (their 4T models)

and likely there are others.

Yet even two generations out ("Monstro"), you will still have a rolling shutter. You say, our readout will be so fast that there will be very little skew. Why not just make a global shutter and be done with it? Wouldn't that be easier for Marketing, anyway? (1) We have zero skew, or (2) We have a rolling shutter (instant groan from audience), but it's not that bad because . . . (insert technical discussion here). Not as catchy, is it?

Besides, more noticeable than skew (and maybe harder to stomp out even with superfast readouts) are flickering lights and what you might call eew:

[edit:] Note: pic NOT from a RED camera.
2100_1221792558.jpg

[edit:] Note: pic NOT from a RED camera. It's an example from AWAIBA

Having to watch your panning speed is one thing. But do we also need to be careful around ceiling fans, aircraft propellers, and certain lights?

It's not just a complaint from purists and technophiles. Discussion ripples across other web sites, (a) warning against such-and-such camera because it has rolling shutter, or (b) praise for such-and-such camera because it has a global shutter.

I'm almost sure you have a good reason, some great disadvantage that a global shutter CMOS would bring (at least with current technology). If so, please help settle down this rolling controversy.
 
But you also want more sensitivity/less noise, do you?
Global shutter for CMOS is reducing sensitivity! The balance is tricky, just like the Arri D20/21 the Red still has less sensitivity than a CCD like Sony F35 (which has it's own problems with blooming and streaking).

Plus, to get such images you'll need VERY short exposure times. I did my own tests with an electric fan and didn't get such images with the Red One at any reasonable shutter speed for cinematic use. It's already much better than many others. Thanks to Jim, the Red is a filmmaker's tool, not a scientific one for crash tests or the like.
 
Hey Combatentropy, are you trying to pass that pic off as being taken on RED? It sure seems that way to me but you've ripped it off the Awaiba site!

You wanna have a conversation why not actually post a pic from the RED or at least have the courage to state your picture's origins.

Yes rolling shutter is an issue but, as Jim's already stated on other threads, RED's censor is amongst the fastest to reset in the world.

Just sayin'...
 
Kaya,

I do not exactly see why it would be more expensive. Maybe there are differences in then R&D, yep, that could cause a different price. The mass production of a sensor doesn't really change the price. CMOS semiconductor fabs charge more or less per wafer/item size. As the sensors would be the same size, the price will not really differ, regardless if its a 12 MPixel global shutter or a 12 MPixel rolling shutter.

The question is how much other electronics will differ, depending on the design. The slowest rolling shutter allows for an electronics that starts reading while exposing, all at the same time. But making it "superfast" in readout requires almost the same approach as a global shutter, ie. you need to first expose, then transfer ultrafast all values into a buffer memory, and then let a "slow" electronic do the processing (having 1 frame time to do it).

Its merely the same thing, the only problem is the sensor design itself. There is always a trade in one or another direction. And the most expensive thing on the sensors are the exposure masks for the CMOS wafers. But compared to an Intel CPU they are damn cheap, because you do not need a 45nm process in first place. But maybe that would be a good idea, cause then you can shrink a lot of electronic parts within the sensor, leaving lots of area for the exposure. Or make a 3D stacked design, which has the A/D and buffer memory underneath the pixel (I guess that will take some years to go, but there are CPU designs considering such approaches...).

For a perfect global shutter you would need almost one A/D per photo site (to stress that phrase). But there are other solutions to overcome this :)

In the end it comes down to a simple question:

Will Jim change it or not for a global vs. a rolling shutter. I do remember very well the long discussions in the beginning of RED about exactly this. Jim was very deeply involved in it, I guess more than anything ever after. It was kind of a survey thing. I do not exactly remember the pro's and con's discussed back then, but there were reasons to go the way it went.

I aggree that a global shutter would be a good thing with regards to "how film is". If it can be achieved over no big trade compared to the rolling shutter, I would surely love to see it.

Or in other words: If a global shutter can be made with the same sensing bit depth and quality as the current rolling one, I would prefer to have a global shutter over an even more sensitive but rolling rolling one :)

Axel
 
Petros Nousias said:
wouldnt it be even simpler if the sensor exposed side to side instead of top to bottom and be closer to the way the shutter moves in a film camera?
Click to expand...

That depends on the film camera. Some have the shutter on the side which makes the movement top to bottom.
 
lewis said:
Wouldn't it be more simple to shoot a fan and post it? Someone got a Red and a fan and wants to do the trick? :)
Click to expand...

Here you go Lewis.
fan.jpg

fan%20sharpned.jpg


this was shot with a 1/48th shutter so too much motion blur to clearly make out the blade. However in motion there is no evident skew.
 
bettsy said:
Hey Combatentropy, are you trying to pass that pic off as being taken on RED? It sure seems that way to me but you've ripped it off the Awaiba site!

You wanna have a conversation why not actually post a pic from the RED or at least have the courage to state your picture's origins.
Click to expand...

Why would I try to pass it off as from RED while linking to the source?

I have edited my post to clarify that my fan pic is not from a Red.

And your comments about ripping and courage remind me not to assume someone else's motives:

As for ripped, I think it falls under fair use. It's for educational purposes. I even uploaded a copy so as not to misuse Awaiba's bandwidth.

As for courage, actually, I assumed that people would think it was not from RED because it's monochrome and grainy and just doesn't look like a RED image. I don't have a RED, that image was at hand, and although it's rolling shutter artifact is probably worse than RED's, I thought it would make it clear what kind of artifact to look for. The other picture already posted on this thread is just the kind of trials I was hoping to stoke.

I'm not seeking to put RED down. I'm asking as clearly as I can why RED (along with other companies like Sony) would continue to use rolling shutters when there are already CMOS sensors with global shutters.

After reading your post, though, I can see how someone might get confused, so I clarified.
 
Thanks for the clarification.

Whilst we need to play squeaky wheels sometimes, we need to keep the hysteria to a minimum. There are folks with RED cameras trying to earn a living and many naysayers and luddites would look no further than your original post to decide the camera is no good and shoot HDCam or whatever.
 
I just tried shooting my ceiling fan at 50th look's normal to me...
When i go through the footage frame by frame i can just notice a small bit of curvature, just.... or is there..... naaaaa... to much motion blur, cant tell.

Just shot if at 500th of a second, looks fine.... hey! I a can see a spider hanging on for dear life. cooooooool.

Just shot it at 200th...YES YESY I can send bend!!!! yaaaaaaaaaay.
Showed my kids just then, I said what's wrong with the fan in this shot guys. They said, what's wrong with you dad... They saw nothing.

This slew conversation is sooooooo 70's

moving on.
 
Did anybody try to look on the fan and blink your eyes as fast as you can?
Here you have rolling shutter.
Should I upgrade my eyes because of it or install global blink on my eyes?
I guess I can leave with my eyes as it is.
I know, I can buy these 3D glasses for watching the 3D computer monitors with LCD shutter build in and wear it all the time, this is the perfect solution.
 
im not a big fan of global shutter.
rolling shutter helps red look more filmic.

I would like to have them both. Global shutter is nice too.. i can shoot in normal flourescent. which means that I can shoot in malls, indoor soccer halls.. classrooms... buildings.. u name it.
 
I would agree. Everyone wants to get rid of rolling shutter, but when you look at global shutter cameras, they look very videoey and not filmic at all.

BTW, global shutter will have flicker issues too. It won't help much with shooting anywhere although the resultant flicker will appear a little bit different.
 
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