Rolling Shutter on FX1

[Brooks Graham]

I'm about to take delivery on my first CMOS cam (EX3) and had some time this evening to devise a test to see where the rolling shutter problem hits. I grabbed my trusty FX1 to test my setup (a contrived scene with lots of strong vertical elements, etc.) and what to my wondering eyes did appear, but horrible rolling shutter artifacts - on a CCD-based camera!

The faster I panned, the worse it got. I had never seen this effect on this camera before in my three year relationship with it.

I did a quick log & capture in FCP and the rolling shutter phenomenon was not in the footage at all. Weird. But certainly a relief.

Could it be that the LCD on the camera refreshes so slowly that it exhibits rolling shutter?

In any event, after some thought, it occurred to me that given the kind of work I do and that I've never noticed any rolling shutter on the FX1's LCD before, I'll probably be just fine with the EX3. ;-) (although I'm still going to test it thoroughly once it gets here!)

[Greg Laves]

I am pretty sure that the FX1 has a global shutter, not a rolling shutter. But I am constantly amused at the people who will violently pan back and forth in order to exhibit the problem of a rolling shutter. But what they are producing is footage that no one would ever want to use anyway whether it was shot with global shutter or a rolling shutter. Enjoy your new toy. I am jealous.

[Simon Wyndham]

Greg, that is exactly what I think. Most of the rolling shutter issues only show themselves at the extremes of situations. Strobing flashes can be an issue, but in all the footage I have shot normally with an EX1 and EX3 I have never once even noticed any skewing etc.

[Ken Darling]

Originally Posted by Simon Wyndham

Greg, that is exactly what I think. Most of the rolling shutter issues only show themselves at the extremes of situations. Strobing flashes can be an issue, but in all the footage I have shot normally with an EX1 and EX3 I have never once even noticed any skewing etc.

Agreed, but when one is shooting those extremes for a purpose, rolling shutter can result in lost income.

I shoot extreme close up footage, but the rolling shutter has rendered hours of footage unsuitable, meaning I have to shoot again. But I have to wait months for nature to work her magic again...

After the Mumbai attacks before Christmas I saw for the first time broadcast footage that exhibited rolling shutter artifacts. It was blindingly obvious (partial exposure from camera flashes) and it looked awful. The wife didn't spot it, though.

Personally, I won't entertain the idea of purchasing another CMOS camera until the rolling shutter issue is resolved. I'm sure the issues will be ironed out very shortly.

Ken

[Simon Wyndham]

Ken, do you have any examples we could look at?

The rolling shutter can be resolved now, by using a global shutter. But by doing so the price of the cameras would go up a lot.

At this sort of price level there are compromises to be made. The CMOS technology is allowing lower end cameras to have full 1920x1080 chips along with very low smear levels and good dynamic range. The alternative is to have a CCD with a global shutter, much higher smear levels, but with lower resolution chips. Without CMOS the EX1 and EX3 with 1/2" chips would not be possible.

With the larger cameras such as the PDW-355 and PDW-700 price is not so much of an obstacle so those cameras can use global shutter CCD's with a much higher performance all round.

So in short the rolling shutter isn't going away any time soon unless they start using global shutter CMOS, which is unlikely given the complexity involved. It is worth taking into consideration that Red also suffers from this, and to a degree film cameras can also suffer from a similar issue.

The wife didn't spot it, though.

Exactly. Most non camera people either do not notice things, or see some camera flaws simply as "that is what video looks like", whereas many camera people over analyse things and notice artifacts in the picture that a general audience simply wouldn't notice or care about.

Cameras at the lower end have always had issues of some kind. Be it very high smear, very high noise, terrible highlight handling, extremely low resolution chips etc. CMOS has changed the game and eliminated many problems while bringing costs down at the same time. Now CMOS has introduced its own set of problems, but IMHO the advantages outweigh the disadvantages. If you know the issues then you can work around them, just like we worked around the issues of older inexpensive CCD based cameras.

[Greg Laves]

Ken, I am curious how rolling shutter ruined extreme close up footage. I am envisioning an extreme close up of snow melting or ants running through a forest floor. I don't I guess I don't understand what you are trying to do. Do you have an example? Or can you explain your situation? Thanks.

[Ken Darling]

@Simon, I don't have any sample I can post at the moment as I deleted the footage from my drives. I will try to fish some clips out when time permits.

@Greg, the extreme close ups I was shooting were plants (stamen, anthers, pollen, petals, buds, etc). The shooting was done with either a 10x achromatic lens or a reverse mounted 50mm prime lens; camera (HV20) tripod mounted.

The problem was that the slightest breeze turns into a hurricane! The rolling shutter caused the plants' movements to be greatly distorted. I tried changing shutter speeds, but to no avail.

I needed some slow motion shots, too, but the distortion is still highly visible.

I have an FX1 to work with, but being winter, there is nothing suitable to film... Roll on spring!

In general everyday use, the rolling shutter is NOT an issue (at the right shutter speed).

Ken

[Greg Laves]

Ken, I just assumed you were assumed you were using a V1 or Z7 or something similar. I have never even seen a Canon HV series camcorder or any footage shot on one. At least in real life. So I don't have any idea of how their rolling shutter differs from the Sony camcorders. But I have shoot a lot of extremly fast moving footage (Blue Angels for example) with my V1 and I have never had to discard anything because of any rolling shutter artifacts. That is why I just couldn't imagine how any close up footage could exhibit rolling shutter problems. You learn something new every day, I guess.

[Ken Ross]

I've shot aerial stuff with both the HV20 and my new HG21, both with CMOS, both with rolling shutter. I just haven't seen any rolling shutter issues. I really think this thing is overplayed IMO.

I don't think, from the footage I've seen posted, it's any different with the Z5/FX1000. As long as you don't use slo mo during scenes with tons of flashes going off, I don't see this a deal break. Both sensor types have their pluses and minuses and from what I've seen of the low light capabilities of the Z5/FX1000, those pluses are pretty big.

[Ken Darling]

Originally Posted by Ken Ross

I've shot aerial stuff with both the HV20 and my new HG21, both with CMOS, both with rolling shutter. I just haven't seen any rolling shutter issues. I really think this thing is overplayed IMO.

I agree that it is, in many cases, overplayed. But there are cases when it is unacceptable, as I found to my cost.

When I first used the HV20 I tried hard to find what would 'break' it, what scenarios would I commonly be using the camera in that would cause rolling shutter artifacts to be an issue.

I found none. Fast horizontal/vertical movement, OIS on/off, high frequency juddering (travelling over a very bumpy tarmac), various shutter speeds... nothing produced video like those nasties I'd seen posted on various boards.

But then I found the weak spot. Yikes!

Anyway, I have my FX1 for the extreme close ups and broadcast work; for everything else I use the HV20 because it's just so good. When the FX1 needs replacing the rolling shutter issues (insignificant as they may be) will probably be resolved. I hope.

As had been said before, the camera is just a tool and 99% of the time one can work around the limitations.

Ken

[Ken Ross]

Originally Posted by Simon Wyndham

Exactly. Most non camera people either do not notice things, or see some camera flaws simply as "that is what video looks like", whereas many camera people over analyse things and notice artifacts in the picture that a general audience simply wouldn't notice or care about.

When I have yet to see these issues, I sure as heck won't talk myself into seeing them! :)

Further, I can't imagine how the newer Sony cams (Z5/FX1000) can be so much worse than the cheap Canons I've had. What can be different about Sony's implementation of rolling shutter. Someone had posted on another thread that an FX1000 clip exhibited some bad evidence of rolling shutter. This clip was supposed to show a 'bending' of pillars in the back of a church during quick pans. I looked at that clip several times and did so critically....there was NO bending of those pillars. I wasn't the only one that thought that.

Sometimes I think people see things that simply aren't there because they are convinced the magnitude of this issue is so serious. Now I have seen rolling shutter issues during slo mo clips while numerous flashes were going off, but that's legit.

[Simon Wyndham]

Sometimes I think people see things that simply aren't there because they are convinced the magnitude of this issue is so serious.

I agree. In fact when I was messing around trying to induce the issue the other day I found that what was actually perspective distortion, lens distortion, and camera angle during movement could be confused for a CMOS rolling shutter issue. I panned very quickly and made sure that the vertical object stopped halfway through so that theoretically if there was an issue it would bend and then I would see it straighten when the camera stopped. No such thing happened.

The Sony EXMOR equipped cameras I know have some compensation for rolling shutter issues in the way that they use a new parallel readout system so the information can be taken off the chips much faster than normal CMOS's.

I have only seen one example of rolling shutter on the EX1 on YouTube. All of the others I have seen didn't show anything of note at all, and I am sure that people were looking for issues that weren't there. Wobbly handheld shots for one thing just looked like, well, wobbly handheld shots. No jello picture, just typical camera wobble from being supported by hand.