LED Banding with mechanical FP shutters

[JimKasson]

Since the advent of fully-electronic (but not global) shutters, there have been many complaints about lighting banding. Usually, if you're not dealing with stage lighting, the modulation frequency is twice the mains frequency, and you can find a shutter speed to ameliorate the problem.

But not always.

I recently encountered this sneaky little light -- it's the one closest to the camera.

When you dim it a bit and take a Z7 silent-shutter picture with it as the illuminant:

19 or so stripes, right? 1/16 second or so scan time, so the modulation frequency is about 19*16, or around 300 Hz.

Now let's take picture with EFCS:

And with the fully-mechanical shutter:

So, in this brave new lighting world, using an old-fashioned shutter is no panacea.

By the way, did you notice that the EFCS first curtain has a sharper cutoff then one in the the all-mechanical shutter?

Jim

--
Posted as a regular forum member.
https://blog.kasson.com

 

[Lance B]

And so the plot thickens.

Thank you for the info, Jim. As always, much appreciated.

 

[jch2103B]

Interesting, as always. I assume this behavior isn't restricted to Z7/Z6, or even mirrorless.

 

[JimKasson]

1. jch2103B wrote:

Interesting, as always. I assume this behavior isn't restricted to Z7/Z6, or even mirrorless.

You are correct. But it’s especially relevant to MILCs, because silent shutter is not often used with DSLRs. That means they sometimes get tarred with a brush that occasionally applies equally as well to flapping mirror cameras.

 

[fad]

It is total chaos out there with lightbulbs. I am upgrading to a better brand of smart switches, and it's a total crap shoot as to which bulbs will work with what smart switches.

 

[michaeladawson]

So Jim, why title this thread Z7 banding? Sounds like a general warning about certain light sources. Misleading subject lines?

 

[JimKasson]

So Jim, why title this thread Z7 banding? Sounds like a general warning about certain light sources. Misleading subject lines?

This is a forum about Z cameras. The test was done with a Z7; so the pictures are of banding with the Z7. The warning is applicable to all Zx camera users.

But you are right in that if affects most, if not all, FP shutter cameras.

Jim

--
Posted as a regular forum member.
https://blog.kasson.com

 

[Sara Valentine]

Since the advent of fully-electronic (but not global) shutters, there have been many complaints about lighting banding. Usually, if you're not dealing with stage lighting, the modulation frequency is twice the mains frequency, and you can find a shutter speed to ameliorate the problem.

But not always.

I recently encountered this sneaky little light -- it's the one closest to the camera.

When you dim it a bit and take a Z7 silent-shutter picture with it as the illuminant:

19 or so stripes, right? 1/16 second or so scan time, so the modulation frequency is about 19*16, or around 300 Hz.

Now let's take picture with EFCS:

And with the fully-mechanical shutter:

So, in this brave new lighting world, using an old-fashioned shutter is no panacea.

By the way, did you notice that the EFCS first curtain has a sharper cutoff then one in the the all-mechanical shutter?

Jim

Am I in the ballpark if I estimate the shutter duration to be about 1/250 sec?

 

[JimKasson]

Since the advent of fully-electronic (but not global) shutters, there have been many complaints about lighting banding. Usually, if you're not dealing with stage lighting, the modulation frequency is twice the mains frequency, and you can find a shutter speed to ameliorate the problem.

But not always.

I recently encountered this sneaky little light -- it's the one closest to the camera.

When you dim it a bit and take a Z7 silent-shutter picture with it as the illuminant:

19 or so stripes, right? 1/16 second or so scan time, so the modulation frequency is about 19*16, or around 300 Hz.

Now let's take picture with EFCS:

And with the fully-mechanical shutter:

So, in this brave new lighting world, using an old-fashioned shutter is no panacea.

By the way, did you notice that the EFCS first curtain has a sharper cutoff then one in the the all-mechanical shutter?

Jim

Am I in the ballpark if I estimate the shutter duration to be about 1/250 sec?

No, it was about 1/2000, to get the full effect of the light modulation.

--
Posted as a regular forum member.

the last word the last word - Photography meets digital computer technology. Photography wins -- most of the time.

Photography meets digital computer technology. Photography wins -- most of the time.

blog.kasson.com

 

[Sara Valentine]

Since the advent of fully-electronic (but not global) shutters, there have been many complaints about lighting banding. Usually, if you're not dealing with stage lighting, the modulation frequency is twice the mains frequency, and you can find a shutter speed to ameliorate the problem.

But not always.

I recently encountered this sneaky little light -- it's the one closest to the camera.

When you dim it a bit and take a Z7 silent-shutter picture with it as the illuminant:

19 or so stripes, right? 1/16 second or so scan time, so the modulation frequency is about 19*16, or around 300 Hz.

Now let's take picture with EFCS:

And with the fully-mechanical shutter:

So, in this brave new lighting world, using an old-fashioned shutter is no panacea.

By the way, did you notice that the EFCS first curtain has a sharper cutoff then one in the the all-mechanical shutter?

Jim

Am I in the ballpark if I estimate the shutter duration to be about 1/250 sec?

No, it was about 1/2000, to get the full effect of the light modulation.

A frame with 1.5 cy / 360 cy/sec gives 0.0042 sec or near 1/250. Why am I off by a factor of 10?

 

[JimKasson]

Since the advent of fully-electronic (but not global) shutters, there have been many complaints about lighting banding. Usually, if you're not dealing with stage lighting, the modulation frequency is twice the mains frequency, and you can find a shutter speed to ameliorate the problem.

But not always.

I recently encountered this sneaky little light -- it's the one closest to the camera.

When you dim it a bit and take a Z7 silent-shutter picture with it as the illuminant:

19 or so stripes, right? 1/16 second or so scan time, so the modulation frequency is about 19*16, or around 300 Hz.

Now let's take picture with EFCS:

And with the fully-mechanical shutter:

So, in this brave new lighting world, using an old-fashioned shutter is no panacea.

By the way, did you notice that the EFCS first curtain has a sharper cutoff then one in the the all-mechanical shutter?

Jim

Am I in the ballpark if I estimate the shutter duration to be about 1/250 sec?

No, it was about 1/2000, to get the full effect of the light modulation.

A frame with 1.5 cy / 360 cy/sec gives 0.0042 sec or near 1/250. Why am I off by a factor of 10?

You're looking at the mechanical shutter scan time, not the shutter speed. At 1/2000, a slit travels across the sensor.

Jim

--
Posted as a regular forum member.

the last word the last word - Photography meets digital computer technology. Photography wins -- most of the time.

Photography meets digital computer technology. Photography wins -- most of the time.

blog.kasson.com

 

[just Tony]

So Jim, why title this thread Z7 banding? Sounds like a general warning about certain light sources. Misleading subject lines?

This is a forum about Z cameras. The test was done with a Z7; so the pictures are of banding with the Z7. The warning is applicable to all Zx camera users.

But you are right in that if affects most, if not all, FP shutter cameras.

Jim

I'm going with "all".

[Not directed to you Jim, but to those for whom your message is new] Arc lighting had a strong power line modulation, which Nicola Tesla addressed by inventing a 10 KHz system to suppress the audible buzz prevalent in 60Hz versions. Many of us were introduced to this issue by fluorescent lamps due to their low persistence. Pulse-width modulated LEDs upped the ante.

The slow slit-scan effect can result in other artifacts even in continuous lighting:

http://www.artfuldancer.com/Lessons/topics/DanceProduction/Shutters.htm

Leaf shutters are the original global shutters. High speed electronic flash is (in effect)another type.

--
Render unto Digital, that which is Digital's,
and unto Analog, that which is Analog's

 

[olyflyer]

It has nothing to do with the Z7 or LED lighting. The problems is the same with ANY camera, even old film still and movie cameras and not just LED light but EVERY type of flickering light, for example florescent tube, and low energy lights, which are very common in industry and homes since like forever.

So the title of this thread is wrong and confusing those who don't understand the reasons for this phenomenon.

 

[JimKasson]

It has nothing to do with the Z7 or LED lighting. The problems is the same with ANY camera, even old film still and movie cameras and not just LED light but EVERY type of flickering light, for example florescent tube, and low energy lights, which are very common in industry and homes since like forever.

So the title of this thread is wrong and confusing those who don't understand the reasons for this phenomenon.

I have never seen fluorescent lighting produce anything like this. For one, most fluorescents these days use an electronic ballast. For another, the phosphors in most fluorescents have longer decay times than we're seeing here.

I never worry about fluorescent lighting with mechanical shutters, and I haven't had any issues in decades.

Jim

 

[Horshack]

Cool stuff Jim. Global CMOS shutters in mass-produced cameras can't get here fast enough

 

[JimKasson]

Cool stuff Jim. Global CMOS shutters in mass-produced cameras can't get here fast enough

Note that this is bad enough that even a leaf or global shutter would have a problem at high shutter speeds. Not with banding, but with uneven exposure from shot to shot.

Jim

 

[olyflyer]

It has nothing to do with the Z7 or LED lighting. The problems is the same with ANY camera, even old film still and movie cameras and not just LED light but EVERY type of flickering light, for example florescent tube, and low energy lights, which are very common in industry and homes since like forever.

So the title of this thread is wrong and confusing those who don't understand the reasons for this phenomenon.

I have never seen fluorescent lighting produce anything like this. For one, most fluorescents these days use an electronic ballast. For another, the phosphors in most fluorescents have longer decay times than we're seeing here.

I never worry about fluorescent lighting with mechanical shutters, and I haven't had any issues in decades.

Jim

Mechanical, EFCS and electronic shutter.

If you haven't seen in decades then you probably not shot under pure florescent tube light in decades. If it is mixed with other type of light then the phenomenon can be totally erased.

Anyway, the thread title is wrong and confusing. It has nothing to do with the Z cameras, or if it is mirrorless or not, and also not LED related. I have LED in all my rooms except the washing room, no problems at all in any rooms except the washing room. However, with the right shutter speed it is easily avoided.

 

[Anonymous Pi]

Cool stuff Jim. Global CMOS shutters in mass-produced cameras can't get here fast enough

Note that this is bad enough that even a leaf or global shutter would have a problem at high shutter speeds. Not with banding, but with uneven exposure from shot to shot.

Jim

So, is there a solution to or workaround for this problem, and, if so, what is it?

 

[JimKasson]

Cool stuff Jim. Global CMOS shutters in mass-produced cameras can't get here fast enough

Note that this is bad enough that even a leaf or global shutter would have a problem at high shutter speeds. Not with banding, but with uneven exposure from shot to shot.

Jim

So, is there a solution to or workaround for this problem, and, if so, what is it?

Slow shutter speeds. That's the traditional one.

Jim

 

[JimKasson]

It has nothing to do with the Z7 or LED lighting. The problems is the same with ANY camera, even old film still and movie cameras and not just LED light but EVERY type of flickering light, for example florescent tube, and low energy lights, which are very common in industry and homes since like forever.

So the title of this thread is wrong and confusing those who don't understand the reasons for this phenomenon.

I have never seen fluorescent lighting produce anything like this. For one, most fluorescents these days use an electronic ballast. For another, the phosphors in most fluorescents have longer decay times than we're seeing here.

I never worry about fluorescent lighting with mechanical shutters, and I haven't had any issues in decades.

Jim

Mechanical, EFCS and electronic shutter.

If you haven't seen in decades then you probably not shot under pure florescent tube light in decades. If it is mixed with other type of light then the phenomenon can be totally erased.

Anyway, the thread title is wrong and confusing. It has nothing to do with the Z cameras, or if it is mirrorless or not, and also not LED related. I have LED in all my rooms except the washing room, no problems at all in any rooms except the washing room. However, with the right shutter speed it is easily avoided.

Looks like you don't have an electronic ballast. That's a 100 Hz rep rate.

https://en.wikipedia.org/wiki/Electrical_ballast

I've been using them for decades. Well, I'm hardly using any any more, because I've pretty much converted over to LEDs.

Jim

--
Posted as a regular forum member.
https://blog.kasson.com