Rolling Shutter Issues? Any one else notice?

T

Troy Ruff

Well-known member
The first couple of days I received the AF100 I did some tests and one of them was with a non gun. It is a on set gun that shoots a flash with a flame to get a really good looking muzzle flash. You can see the rolling shutter roll up. It is really noticeable. Let me know if anyone else has seem this. Thanks

Troy

 
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I've seen similar things with any short-term event, like a strobe for still photography. Even if you have global shutter camera, there's a chance you'll miss the event when the camera's shutter is closed. For a rolling shutter, the physics suggests you'll always get this unless the even is perfectly sync'd with the shutter, and/or last longer than the shutter opening. That's my experience anyway (and I was bit by this over the weekend shooting with a 5D). - Tim
 
TimTheFoolMan said:
I've seen similar things with any short-term event, like a strobe for still photography. Even if you have global shutter camera, there's a chance you'll miss the event when the camera's shutter is closed. For a rolling shutter, the physics suggests you'll always get this unless the even is perfectly sync'd with the shutter, and/or last longer than the shutter opening. That's my experience anyway (and I was bit by this over the weekend shooting with a 5D). - Tim
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Wow so no fixing this? I have never seen this before. I have done tons of slow mo, with GH1 and gun fire. Never an issue. But when we shot this with the Af 100, every single time the gun went off, it showed the shutter. thanks for helping me understand whats going on. Boo for the issue, any suggestions on how to get around it, but still shoot in 60fps? thanks again
 
Could increase the shutter speed? won't look as filmic but the time when the shutter is closed will be shorter. I am not sure if this would solve the problem tho.
 
jburke14 said:
Could increase the shutter speed? won't look as filmic but the time when the shutter is closed will be shorter. I am not sure if this would solve the problem tho.
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Good suggestion, Ill try it, but your right I don't know if it would fix it completely. Thank you
 
Yeah that's a flash band; happens with every 'rolling' shutter mos / cmos chip. You see footage like this all the time on the gossip news shows (access hollywood, insider, or tmz) some star entering a restaurant and the footage is full of flash bands as the photographers take pictures. I've also heard dslr wedding shooters gripe about how they had the perfect shot - but grandma took a flash picture and ruined it (because it left this band artifact).

@ :23 seconds in the video I see a RED; do the same test with that cam and show us the results.

The way around it is to use a 'global' shutter ccd camera - or perhaps there is a plug in for your NLE that will compensate?
 
jburke14 said:
Could increase the shutter speed? won't look as filmic but the time when the shutter is closed will be shorter. I am not sure if this would solve the problem tho.
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That might help, but only to the extent that the shutter opening time is less than the duration of the "flash event." Even then, you've got the risk of the event starting mid-way through a shutter opening/sensor scan.

I'm baffled how you never saw this with a GH1. I've seen it on every DSLR.

Sadly, I've not been able to convince the director of my current project to let me use my HVX instead of his 5D, so instead we're faking the camera flash with a series of stills that were back lit. - Tim
 
I guess the trick is that if you want any quick burts of light, flashes, bangs, to do them in post? Assuming you have the knowledge base to do such a thing.
 
I worked on few films shot on Red where all the muzzle flashes were added in post. I would asume it was done for the same reasons. I must admit that clean plates of people shooting guns without muzzle flash looked quite silly. :D
 
Film cameras exhibit this same problem too. It is not unique to CMOS, though it is worse with slower read/reset times.
 
I agree with heavyG, I personally notice it but no one else in my family can tell. You'll see flash bands on any rolling shutter CMOS camera.. RED One, Alexa, etc. etc.
 
Sweet thanks everyone for your knowledge. I am surrprised as well that I have not seen this with my gh1. But now I know. I have almost always done my muzzle flashes in post so it hasn't been a problem. Actully now that I think of it, the shots fired with my gh1 was mostly smoke not much flame. Well any ways thanks everyone. :) I'm still loving my new af 100.
 
It's a fact of physics, not a problem unique to the AF100.

There are simply some things we have to recognize and find ways around, not unlike one of my favorites, wagon wheels spinning in the "wrong" direction.

If you can't use long duration flashes, you can "fix it in post," most commonly by averaging the two adjacent frames to replace the offending one.

Good shooting and best regards,

Leo
 
TimTheFoolMan said:
I'm baffled how you never saw this with a GH1. I've seen it on every DSLR.
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I'm baffled too. This is a known issue with all CMOS chips, including the RED. I own a GH1, RED MX, and the AF100. I have yet to test this with the AF100, but have seen it on both the GH1 and the RED MX I own. Some cameras have faster refresh rates to help, but it's still always an issue with CMOS. Before the DSLR craze, the Sony's were the worst ones. But now with the advent of the DSLR's it's becoming more and more common and more and more acceptable as well. I personally hate it and avoid it if I can. If you can, do muzzle flashes in post.
 
Brian@202020 said:
I'm baffled too. This is a known issue with all CMOS chips, including the RED. I own a GH1, RED MX, and the AF100. I have yet to test this with the AF100, but have seen it on both the GH1 and the RED MX I own. Some cameras have faster refresh rates to help, but it's still always an issue with CMOS. Before the DSLR craze, the Sony's were the worst ones. But now with the advent of the DSLR's it's becoming more and more common and more and more acceptable as well. I personally hate it and avoid it if I can. If you can, do muzzle flashes in post.
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oh yes Im glad I know now, like I said earlier, I am amazed I haven't seen it either. All well, I will always do my flashes in post, for sure. Thanks
 
Ticheli said:
It's a fact of physics, not a problem unique to the AF100.

There are simply some things we have to recognize and find ways around, not unlike one of my favorites, wagon wheels spinning in the "wrong" direction.

If you can't use long duration flashes, you can "fix it in post," most commonly by averaging the two adjacent frames to replace the offending one.

Good shooting and best regards,

Leo
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Do bicycles wheels do this too?
 
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