topic 5d Mark IV Metering / over exposure with same settings and lighting in EOS DSLR & Mirrorless Cameras

5d Mark IV Metering / over exposure with same settings and lighting

sdkstudio — Tue, 30 Oct 2018 17:35:54 GMT

I'm shooting product and taking several shots with same settings with the following: Canon EOS 5D Mark IV Lens EF100mm f/2.8 Macro USM Setting f32 / 1.6 ISO 100 without making any changes or any adjustments to lighting or settings, every 3rd or 4th shot i get an overexposed image. below is 2 examples that i just shot for this post

Re: 5d Mark IV Metering / over exposure with same settings and lighting

kvbarkley — Tue, 30 Oct 2018 20:33:27 GMT

I don't remember whether it was this camera, but others have complained about the same thing.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

TCampbell — Tue, 30 Oct 2018 20:45:17 GMT

Since these aren't individual images with EXIF data, I can't inspect camera settings or what the camera did.

Tell me more about mode & settings used.

(I have no issues with my 5D IV)

Were you using flash and if so, can you share details on that equipment and settings as well?

Re: 5d Mark IV Metering / over exposure with same settings and lighting

Waddizzle — Tue, 30 Oct 2018 21:27:50 GMT

It could be light flicker.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

sdkstudio — Wed, 31 Oct 2018 14:25:50 GMT

i wasn't using a flash. Here's a list of the equipment and settings:

Canon EOS 5D Mark IV Lens EF100mm f/2.8 Macro USM Setting f32 / 1.6 ISO 100

Lighting setting exact for

GVM Dimmable Bi-color LED Video Panel Light set at 6000

These photos have all the properties

Re: 5d Mark IV Metering / over exposure with same settings and lighting

Waddizzle — Wed, 31 Oct 2018 14:45:40 GMT

Light flicker compensation has nothing to do with a flash. Many types of artificial save energy by turning on and multiple times per second, faster than the eye can see.

But, the camera can see it and be fooled by it. Most of the time you get a random under exposure. It really depends on luck. Your solid state lighting is known for creating light flicker.

Another cause of bad exposures is from light entering the viewfinder, especially when the camera is on a tripod. Normally, you head would block light from entering. For this reason 1D series cameras have a cover that can flipped into place that closes off the viewfinder.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

sdkstudio — Wed, 31 Oct 2018 15:25:27 GMT

Thanks for the comments. I'll test with some incandescent lighting since it's continuos.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

ebiggs1 — Wed, 31 Oct 2018 15:36:05 GMT

It has nothing to do with light flicker. Lights don't "flicker" brighter. If they flicker, they flicker off! Call Canon 1 (800) 652-2666

Re: 5d Mark IV Metering / over exposure with same settings and lighting

TCampbell — Wed, 31 Oct 2018 15:55:20 GMT

Many types of lighting (including LED lighting) pump out just one true luminosity ... but they do blink (flirker) rapidly. This includes florescent lights, LED lights, and many others. This is usually not noticeable to people ... but the metering system can detect it.

AC power cycles 60 times per second. So it's possible with a fast-ish exposure to have the camera take the shot at dim point that the eye doesn't notice. If you burst several frames in a row, you get some bright, some dim, many people think the camera is broken ... but it really did capture what was happen at that moment (nothing wrong with camera).

"Flicker Compensation" is meant to detect the cycle rhythm and have the camera take the shot at the moment the lights are bright so that you don't get under-exposed frames.

LED lights also flicker ... most diodes only put out one true brightness and the perception of dimming an LED comes from changing the frequency of how fast it blinks ... the light "seems" dimmer to us.

Dimmable LEDs are generally blinking fairly fast ... and according to the EXIF data, these are both 2 second exposures.

On the other hand... It shows you used "Manual" exposure.

When you use "manual" exposure... the camera and metering system does not control the exposure. You control the exposure. If you set ISO 100, f/32, and a 2 second expsorure time... then you GET ISO 100, f/32, and a 2 second exposure time. The metering system will offer "advice" ... but it's up to you to set the exposure.

The EXIF data I see in both shots is Manual exposure mode, ISO 100, f/32, and 2 seconds.

Were you using a polarizer and you did you rotate it between shots?

Are you sharing all of the equipment involved in the shoot?

Reflectors?

Flags?

Gels?

Filters?

etc.?

Adjustment to these sorts of things can make a big difference in the result.

Based on the EXIF data... there's no issue with the camera metering system because the metering system didn't control the exposure. It *must* be something else.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

kvbarkley — Wed, 31 Oct 2018 16:10:18 GMT

It could be this - see TCampbells answer, here:

https://community.usa.canon.com/t5/EOS/EOS-5D-MARK-IV-Metering-Issue/m-p/224811

Re: 5d Mark IV Metering / over exposure with same settings and lighting

wq9nsc — Wed, 31 Oct 2018 16:31:29 GMT

LED lighting can create a different flicker effect than florescent or high intensity discharge lights (i.e. mercury vapor or high pressure sodium) because the driver module cuts the actual LEDs on and off very quickly with a near square wave light output pattern from the emitters which go from no to full output and back in nanoseconds. Most of our other artificial light sources provide some significant non-binary transition between on and off states where there is still significant light output over the entire time between peak and minimum; for example even when all excitation is removed you will see a brief glow from the phosphor of a florescent tube and the "off" period is far more brief during the operating cycle compared to what you see after turning the lamp off.

More complex LED arrays use a sophisticated driver module that pulses the LED junctions at a rate far faster than the human eye can perceive and the resultant duty cycle (percent of time it is on) provides the observed light level. But depending upon when the camera shutter is open the camera may see a different number of pulsed light events for each exposure because the shutter isn't synchronized to the driver module. The effective LED array light output is based upon duty cycle which depends upon the width (period of time) of the on pulse and the width of the off period. There are a nearly infinite number of combinations of on and off width and frequency leading to the same perceived light output but with very different captured image effects.

Think of taking a pair of equally timed long exposure images and firing a flash manually where one exposure has three flash events of equal intensity and the other has five so if one is correctly exposed the other will be either over or under exposed. With LED lighting you stand a good chance of having this happen especially with a more sophisticated lighting source that is controlled by an advanced PWM (pulse width modulation) controller instead of a simple line frequency fired module which tends to have a slower modulation rate with extended on time. You could simulate the time lag effect of other types of bulbs with the LED driver but then you would run into a problem of color shift because instead of being modulated between full brightness and off the LED would be driven in a more linear fashion producing some output most of the time but at a lesser intensity and resulting different color temperature given the way LEDs produce visible light.

Some arrays attempting to achieve very high specific light output will pulse the LEDs at a higher current than recommended by the manufacturer providing extreme brightness during the brief on event but protecting the LED from excessive heat by running it at a duty cycle that still provides reasonable, albeit shortened, LED life. These types are likely to be the most problematic for photographic purposes but none of them are going to advertise their method of achieving very high light output at a competitive price. A completely flicker free LED array would be DC driven with a 100% duty cycle but this is going to result in a bigger, heavier, and far more expensive array for the same light output so such a device would tend to be sold at a very high price to specialized users.

For a simple test of the camera simulate the scene using incandescent lighting and see if the over-exposure issue disappears. Incandescent lights powered by AC also have a slight flicker but because of the tremendous thermal lag of the superheated filament it is not visible to humans or a practical camera.

LED lighting has some huge advantages over other light sources but like most new technologies it brings additional problems and unwanted side-effects. One area receiving significant study now is the impact of this differnet flicker environent on human health and behavior including increased potential for epileptic events in children. As we learn more, LED driver protocol will change and some of those changes are going to have various impacts on photography that we will have to learn about and adapt.

Rodger

Re: 5d Mark IV Metering / over exposure with same settings and lighting

ebiggs1 — Thu, 01 Nov 2018 13:42:29 GMT

"I'll test with some incandescent lighting since it's continuos."

You can try that but it will not help. Your problem is not light flicker. You have a correct exposure and then you have an over exposure, by several stops. If light flicker is happening the light flickers off, not brighter. Which is what you would need to get an over exposure. A two second SS will see the same amount of flickers anyway!

Since you are shooting at f32, I will bet the lens is not closing all the way down to f32 on the over exposure. This could be due to a faulty lens and is almost the only way your problem can happen.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

sdkstudio — Sun, 04 Nov 2018 11:20:21 GMT

Thank you ALL for all the input.

"ebiggs1", you are correct, it must be the lens. i tested same senario with my 50 mm and didnt have any issues even when shooting 36 continuous shots. So THANKS again

Re: 5d Mark IV Metering / over exposure with same settings and lighting

TurtleDownUnder — Sun, 04 Nov 2018 11:49:02 GMT

I'm have exactly the same problem. I posted about it earlier today 'problems with exposure'.

The exact same settings, same field of view/subject/background and one turns out fine then completely over-exposed.

I'll be following this thread to see if there's a fix, because I'm throwing away a ton of photos at the moment.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

TurtleDownUnder — Sun, 04 Nov 2018 11:50:04 GMT

I have been having the same problem outdoors so I don't think flicker is the problem

Re: 5d Mark IV Metering / over exposure with same settings and lighting

TurtleDownUnder — Sun, 04 Nov 2018 11:54:10 GMT

I've been having the same issue but outdoors (no chance of flicker). Two shots, same background, subject matter, composition, settings . . . everything seemingly the same and one looks okay, another completely over exposed and blown out. New Canon 5D mark IV and really upsetting

Re: 5d Mark IV Metering / over exposure with same settings and lighting

ebiggs1 — Sun, 04 Nov 2018 14:37:56 GMT

"... I don't think flicker is the problem"

The flicker answer was and is silly. You are getting an overexposure because you are getting more light. Not less light. That is where you need to concentrate your efforts.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

ebiggs1 — Sun, 04 Nov 2018 14:39:12 GMT

"New Canon 5D mark IV and really upsetting"

What lens? Make sure it is working correctly.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

Waddizzle — Sun, 04 Nov 2018 14:44:35 GMT

@TurtleDownUnder wrote:
I've been having the same issue but outdoors (no chance of flicker). Two shots, same background, subject matter, composition, settings . . . everything seemingly the same and one looks okay, another completely over exposed and blown out. New Canon 5D mark IV and really upsetting

With 2 second exposures, I do not think it could be flicker.

But, i would not completely rule it out, either. Unlike analog light sources that merely dim during their “OFF” portion of their flickering, a digital, solid state light source will go completely dark. The human eye just cannot see it go dark. If you fire the shutter at the moment when the solid state light source is dark, then you may wind up with an over exposure.

It is very easy to eliminate this as a source of the trouble by simply enabling “Light Flicker Compensation”, and see if the problem just simply goes away. If it does not, then you know the problem is not flicker. If you are shooting with artificial lighting, then it is probably a best practice to enable LFC, anyway.

Re: 5d Mark IV Metering / over exposure with same settings and lighting

wq9nsc — Sun, 04 Nov 2018 15:04:58 GMT

With more sophisticated LED arrays, the anti-flicker setting in the camera won't have any effect. It is set up to operate at an exact multiple of either of the commonly used 50 or 60 hz line frequencies (line frequency depends upon country/region) and if the flicker rate isn't an exact and recurring multiple of that then the camera anti-flicker algorithm cannot work.

Historically common light sources (florescent strips, high intensity discharge mercury or sodium stadium lights, etc.) will flicker in sync with the applied line frequency. However some LED arrays, in particular those that can operate from an internal or external battery pack or those using a more advanced array, have a driver that is not tied in sync to these commonly used line frequencies so the camera won't detect and correct for the problem. Canon adds this line frequency restriction as a footnote in the manual (at least for the 1DX family).

Rodger