Image Behavior Bug HPX170?

B

Brack

New member
Hello,

Has anyone seen this issue or know what the heck is going on?

I was filming an interview with the HPX170 as usual, however the background image kept oscillating from bright to dim. Very strange, as I had everything set to manual and the background light was fixed in studio. Here is a link to the video of it happening, focus on the subtle color change.

Link:
http://www.vimeo.com/8651405
 
Brack, you're new here, so I apologize that your first post will result in me ranting, but this subject is seriously driving me batty because it keeps happening to so many people. I've been talking about this for years, I wish they'd teach it in film schools and that everyone would learn this early on, without having to learn it during a pro shoot, like you did.

But: (to quote a post I made yesterday, with only the mildest changes)...

Everyone, please, learn this lesson now, and never forget it:
DO NOT EVER USE A SHUTTER SPEED OTHER THAN 1/60TH (NTSC territories) OR 1/50TH (PAL territories) WHEN SHOOTING UNDER FLUOS OR MAGNETIC HMIs.

Ever. Ever ever ever. EVER.

If it's a CMOS camera, you'll get big rolling bars and waves in your footage. I don't care if it's a 7D, a 5D, a GH1, an HV20, a Red One, a Scarlet, an HPX300, an NX5, an HMC40, it doesn't matter -- if it has a CMOS sensor, you cannot cannot cannot cannot go changing the shutter speed away from 1/60th. (or, if you're in PAL territory, 1/50th).

If it's a CCD camera, you'll get a cycling white balance shift in your colors. I don't care if it's a DVX, a Dalsa Origin, an F35, an F23, a VariCam, an F900, a VX1000, it doesn't matter. If it has a CCD sensor, you cannot cannot cannot cannot go changing the shutter speed away from 1/60th (or, if you're in PAL territory, 1/50th).

DO NOT USE 1/50TH OR 1/48th IN NTSC TERRITORY THINKING "It's more film-like". It doesn't matter. If you're shooting under fluos or magnetic HMIs or any ballasted light source, Just. Don't. Change. The. Shutter. Speed. Away. From. 1/60th. Ever. Spread the word, people need to know about this.

Please, for the love of all that's good in your footage, everyone: leave the shutter speed alone. Don't change it. If you're shooting under fluos or HMIs, leave the shutter speed at 1/60th in 60Hz territories, or 1/50th in 50Hz territories.

In a video camera, leave the shutter speed alone. Don't change it. Don't use it to control exposure. Unless you know exactly what you're doing, you run the risk of screwing up your footage in ways (like the CCD color shift, or the CMOS scrolling bars) that you might never anticipate. So take the vow with me, people: "when shooting video, I will leave the shutter speed alone."

Thank you.

I return you now to your regularly scheduled programming.

:D
 
Brilliant! That was it , dammit! Thank. you. very. much. :)
I just checked my camera and sure enough the shutter was turned on at 1/48. I didn't catch it, or it got bumped on. I'm happy it was an easy fix. ...Barry, the louder you rant, the better I hear. :)
 
It doesn't matter what the frame rate is -- if you want to avoid conflicting with fluorescents, you want 1/60th (in the US/60Hz territories) or 1/50th (in PAL territories).

30p and 24p default to 1/50th.
 
1/48 and marching ants etc...

1/48 and marching ants etc...

Hey Barry for 98% I agree with you but I have found that with a good amount of natural light coming into the interior scene and combined with those smaller bulb like fluorescent lighting that 1/48 at 24p on the CANONs 7D, 5D looks awesome. Whether or not you can visually see the difference between 1/48th (1/50th on DSLRs) and 1/100th for sitting interviews is personal preference.

But there is complete SAFE ZONE merit in what you are telling people here. I always like to shoot then look at it closely before continuing on with the actual shot for safety sake. I just met up with Vincent LaForet and he actually said on the CANONs you do not have to worry about NATIVE, so to speak shutter speed, and you can still shoot 23.98 at 50 or 100 etc... taking advantage of the best shutter setting for whats going on in your shot and yes especially with Fluorescents. Some of the CANON HDSLR gurus are running around preaching to stick to the multiple of the frame rate for speed for the BEST look period and that's just not correct for getting rid of banding, marching ants, moire etc.

Barry_Green said:
Brack, you're new here, so I apologize that your first post will result in me ranting, but this subject is seriously driving me batty because it keeps happening to so many people. I've been talking about this for years, I wish they'd teach it in film schools and that everyone would learn this early on, without having to learn it during a pro shoot, like you did.

But: (to quote a post I made yesterday, with only the mildest changes)...

Everyone, please, learn this lesson now, and never forget it:
DO NOT EVER USE A SHUTTER SPEED OTHER THAN 1/60TH (NTSC territories) OR 1/50TH (PAL territories) WHEN SHOOTING UNDER FLUOS OR MAGNETIC HMIs.

Ever. Ever ever ever. EVER.

If it's a CMOS camera, you'll get big rolling bars and waves in your footage. I don't care if it's a 7D, a 5D, a GH1, an HV20, a Red One, a Scarlet, an HPX300, an NX5, an HMC40, it doesn't matter -- if it has a CMOS sensor, you cannot cannot cannot cannot go changing the shutter speed away from 1/60th. (or, if you're in PAL territory, 1/50th).

If it's a CCD camera, you'll get a cycling white balance shift in your colors. I don't care if it's a DVX, a Dalsa Origin, an F35, an F23, a VariCam, an F900, a VX1000, it doesn't matter. If it has a CCD sensor, you cannot cannot cannot cannot go changing the shutter speed away from 1/60th (or, if you're in PAL territory, 1/50th).

DO NOT USE 1/50TH OR 1/48th IN NTSC TERRITORY THINKING "It's more film-like". It doesn't matter. If you're shooting under fluos or magnetic HMIs or any ballasted light source, Just. Don't. Change. The. Shutter. Speed. Away. From. 1/60th. Ever. Spread the word, people need to know about this.

Please, for the love of all that's good in your footage, everyone: leave the shutter speed alone. Don't change it. If you're shooting under fluos or HMIs, leave the shutter speed at 1/60th in 60Hz territories, or 1/50th in 50Hz territories.

In a video camera, leave the shutter speed alone. Don't change it. Don't use it to control exposure. Unless you know exactly what you're doing, you run the risk of screwing up your footage in ways (like the CCD color shift, or the CMOS scrolling bars) that you might never anticipate. So take the vow with me, people: "when shooting video, I will leave the shutter speed alone."

Thank you.

I return you now to your regularly scheduled programming.

:D
Click to expand...
 
Barry,

Maybe I'm missing something really obvious here, but I'm in PAL land (50hz) and the shutter speed option is 1/60 on both my PAL hvx & hpx, I don't have the choice of 1/50th,
 
TubEfingers said:
Barry,

Maybe I'm missing something really obvious here, but I'm in PAL land (50hz) and the shutter speed option is 1/60 on both my PAL hvx & hpx, I don't have the choice of 1/50th,
Click to expand...
You do have it, it's just not obviously labeled. You can use the "shutter" button to turn the shutter off, and when you do, it goes to a default 1/50th shutter speed.
 
As per the flicker for the monitor solution I think I see confusion over the refresh rate of the computer screen (60 hz) and the shutter speed of the camera (1/60).
 
Barry, just so i'm clear on this. you're saying if i'm using kino divas in a studio interview setting, (and those are the only lights in use other than an LED hair light) i should never make my shutter speed slower than 60 fps. if the iris is wide open and it's not bright enough for some reason...add more light.

i have got away with lower than 60fps with daylight bulbs in my divas with exterior windows adding to the fill and background on location. also a couple times i had to be slower than 60fps on a black background with divas and an LED hair light only. would you say i got lucky on those setups, but shouldn't risk it?
 
masnart said:
Barry, just so i'm clear on this. you're saying if i'm using kino divas in a studio interview setting, (and those are the only lights in use other than an LED hair light) i should never make my shutter speed slower than 60 fps.
Click to expand...
No -- Divas are fine. They have high-frequency electronic ballasts and you should be able to use any shutter speed with them.

However, LED lights on dimmers are horrible when used with a CMOS camera. If you're using an LED light at 100% brightness it'll probably be okay, but if it's dimmed at all it will probably screw up your image. I've bought a few of the popular LED lights to test them with, and the results are shockingly bad when you dim them... I'll post a review/article on them soon.

i have got away with lower than 60fps with daylight bulbs in my divas with exterior windows adding to the fill and background on location. also a couple times i had to be slower than 60fps on a black background with divas and an LED hair light only. would you say i got lucky on those setups, but shouldn't risk it?
Click to expand...
No, you didn't get lucky, you were using lights that don't cause the problem. (and good on you for doing it!)

The lights that cause the problem are magnetic-ballast fluorescents, which would more likely be office overhead lights, or shoplights, or things like that. Also magnetic-ballast HMI lights, or sodium-vapor streetlights, or mercury-vapor stadium lights. All of those have the potential to cause the problem.
 
divas and LED lights

divas and LED lights

ok, thanks for the clarification barry. i appreciate it. the LED light in my setup is a high-end Zylight Z90. I usually use it for a hair light or a quick background light. it's a great light and offers a lot of flexibility because it has built in tungsten or daylight and you can dial in any color you want for other uses. i'd be interested to know if this light gives you any trouble. so far so good for me.

thanks,
glenn

-------------
Barry_Green said:
No -- Divas are fine. They have high-frequency electronic ballasts and you should be able to use any shutter speed with them.

However, LED lights on dimmers are horrible when used with a CMOS camera. If you're using an LED light at 100% brightness it'll probably be okay, but if it's dimmed at all it will probably screw up your image. I've bought a few of the popular LED lights to test them with, and the results are shockingly bad when you dim them... I'll post a review/article on them soon.


No, you didn't get lucky, you were using lights that don't cause the problem. (and good on you for doing it!)
Click to expand...
 
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