Electronic Shutters, Banding & Solving the problem
INTRODUCTION
If you own a mirrorless camera then chances are it offers you both mechanical and electronic shutter options. There are additional choices but for the purposes of this post, we'll stick to these two. If your reading this then you've probably encountered banding and the 'rolling shutter' effect.
I've read numerous posts where camera users have had these problems when using electronic shutters, banding, where lines of uneven exposure run through their photos or the 'rolling shutter' effect where moving images are distorted.
Most replies to these posts correctly point to the electronic shutter as the source of the problem, and more often than not switching to the mechanical shutter as the solution.
I've always liked to understand how something works, not just that it does. Knowing why parameters are placed on some functions assists me to achieve the desired results and avoid the unwanted ones.
I believe 'getting' the reason why will help make you a better photographer.
In this post, I will start with how a Mechanical Focal Plane shutter and an Electronic shutter work. I will also explain how incandescent (traditional tungsten globes) and non-incandescent lighting (Fluorescent, LED, Sodium Discharge) react differently to our AC (Alternating Current) power supply.
I will explain how this results in banding with some shutter speeds but not others, what the banding actually is, and how to avoid it.
I will also explain why you get the 'Rolling Shutter' effect, arming you with the choice to use it creatively or avoid it completely.
Note: In this discussion, I will be concentrating on the traditional 35mm frame and its dimensions of 36mm x 24mm. All dimensions are interchangeable to match the sensor size of any mirrorless camera that uses a focal-plane shutter.
MECHANICAL SHUTTERS
Traditionally the mechanical shutter in 35mm film cameras was constructed of two cloth blinds that travelled horizontally between the rear element of the lens and the film plane. With speeds of 1/60sec or slower, the first blind would set off when the shutter release was fired then stop at a point that left the film frame exposed to the light exiting the lens. The second blind would then cross the frame, cutting off the light and completing the exposure, illustrated in the image below.
With speeds of 1/125sec or faster the second blind would begin its travel prior to the first blind reaching its endpoint. The film was exposed by a slit created by the two blinds as they travelled across the frame. The higher the shutter speed the thinner the slit, illustrated in the image below.
As technology developed the shutter was altered both in its materials, from cloth to titanium and its direction of travel, from horizontal to vertical. As the shutter now had a shorter travel distance. (24mm vertically compared to 36mm horizontally) maximum shutter speeds could be increased.
These changes in maximum shutter speeds included the fastest usable shutter speed for flash photography rising from 1/60sec to 1/125sec.
A quick explanation in regards to flash photography. When using flash the frame needs to be clear of the shutter blinds to accept the flash illumination at the one instant. The fastest shutter speed usable with a horizontal focal plane shutter that allowed a moment between the first blind coming to its finish point, the flash firing and then the second blind commencing its travel was 1/60sec.
With a horizontal focal plane shutter, the first blind had to travel 36mm to reveal the whole frame before the flash could fire. With a vertical focal plane shutter, it only had to travel 24mm. The reduction in the distance travelled meant the sequence was completed in less time allowing the usable shutter speed for flash photography to change from 1/60sec to 1/125sec. (All of the above shutter speed figures may vary slightly depending on the camera brand and its manufacture date but the overall explanation remains consistent.)
Jumping forward to the current crop of mirrorless cameras the mechanical focal plane shutter works basically the same as it did in film cameras. Travelling from top to bottom exposing the camera's sensor as it goes.
ELECTRONIC SHUTTERS
Electronic, rolling or silent shutters are different, they are controlled by the sensor itself simulating the action of the mechanical shutter. Dependent on the shutter speed a row, or rows of pixels are initiated and terminated (turned on and off) as the electronic shutter 'rolls' down the sensor from top to bottom.
The length of time each row is initiated and exposed is determined by the shutter speed. Simulating the size of the slit created by the two blinds of the mechanical shutter. Slower shutter speeds will see more rows of pixels initiated, conversely, with faster shutter speeds the slit, or number of pixel rows initiated is reduced. The images below are created to demonstrate the process, each segment of the grid represents a single pixel.
The difference between the physical slit created by the two blinds used in the mechanical shutter and the simulated slit created by the electronic shutter is the time it takes to complete the exposure cycle. With the mechanical shutter, the exposure cycle equates to the shutter speed.
Using the electronic shutter is different. Each pixel row is exposed correctly, based on the shutter speed set but the exposure sequence, from initiating the top row to the terminating of the last row can take up to 1/10sec and it's this time that gives us the 'Rolling Shutter' effect.
(The actual length of time varies between camera brands and models within each brand. It depends on variables including the physical size of a sensor, it's pixel count and the camera's processing speed)
ROLLING SHUTTER EFFECT
In the images below the cars are travelling left to right at around 60kph. In both images, the cars are sharp, stopped in motion by the 1/2000sec shutter speed but the distortion is clearly visible in the photo on the left.
As the car is travelling at 60kph it's physical position within the frame at the end of it being recorded to the sensor is forward of that when it started.
ELECTRONIC SHUTTERS AND BANDING
Depending on where you live AC (Alternating Current) power grids work on either 50 or 60 hertz, or cycles here in Australia we use 50 hertz, the terms are interchangeable. There are 50 cycles per second and each cycle contains two alternations, one positive, one negative, both deliver voltage and voltage equates to light intensity.
In the diagram above you can see the current sine wave begins at zero voltage, increasing to the highest positive voltage before dropping through zero voltage and alternating to the highest negative voltage. Imagine it as turning on and off 100 times every second. Each alternation is half a cycle, 50 cycles per second = 100 alternations.
INCANDESCENT, NON-INCANDESCENT LIGHTING AND BANDING
The definition of an incandescent light source is one that works by incandescence, which is the emission of light caused by heating the filament. non-incandescent lighting (Fluorescent, LED, Sodium Discharge) is everything else. It's important to remember that no matter the style of light illuminating your subject the current is still alternating at 50 cycles, 100 alternations per second.
The difference is in the way each lighting style behaves. Under incandescent lighting, the bulb's filament doesn't cool down enough at the zero points of the voltage cycle for there to be a visible loss of light intensity so there is no banding when using either mechanical or electronic shutters.
When your subject is illuminated by any of the non-incandescent types of lighting the use of a mechanical shutter also results in an image without banding. This is because the whole of the sensor is initiated/on at the time of exposure.
At the same time, it is possible to achieve an image without banding when using an electronic shutter lit by non-incandescent lights, but there are rules we need to follow.
PUTTING IT ALL TOGETHER
When we shoot with an electronic shutter the pixel rows are turning on and off at a consistent rate, based on the shutter speed set. As the shutter rolls down the sensor, each pixel row initiation needs to receive a consistent voltage/illumination, if it doesn't we will get banding.
Consistent voltage/illumination is the key. So the maximum usable shutter speed is one that initiates the pixel rows for a length of time that delivers a consistent level of voltage/illumination to every row. To achieve this it must fit within an area on the voltage sine wave where it will repeatedly receive that consistent voltage/illumination.
That shutter speed is clearly indicated in the diagram below. 1/100sec consistently receives a full positive or negative alternation from zero to maximum voltage and back to zero again.
So here's the rule: Any shutter speed that is divisible evenly into 100 will work as it receives a consistently repeatable voltage. eg 1/50sec as it receives one complete cycle/2 alternations. 1/25sec also works and will receive two complete cycles/4 alternations.
What if we use a shutter speed of less than 1/100sec but not evenly divisible into 100, say 1/80th.
As you can see in the diagram below each time rows of pixels are exposed at 1/80sec they receive the amount of light generated over slightly less than 1.5 alternations.
In the following simplified diagram, you can clearly see how each block of pixel rows is exposed for the same length of time, 1/80sec but receives a level of voltage over each exposure inconsistent/unequal to the previous or following exposure. Inconsistent voltage/Intensity over varying pixel rows or pixel row blocks equals banding.
Shot on the Fujifilm GFX-50s the results below are a practical example of the explanations above.
BEST PRACTICES
There are pros and cons to each shutter type.
Mechanical Shutter Pros: Use with Flash, less shutter lag, freezes fast-moving subjects Cons: slower maximum shutter speeds, slower maximum continuous frame rate, wear and tear on the shutter mechanism, not silent, possible camera vibration.
Electronic Shutter Pros: Faster shutter speeds, silent operation, no wear or tear, no camera vibration, Cons: Rolling shutter effect, can't use flash, banding.
In regards to using the electronic shutter under non-incandescent lights. It is always best practice to check for banding by shooting a few test frames to confirm all is ok.
CONCLUSION
I hope this post of how both styles of shutter work, how they behave with various forms of lighting and how to solve those issues have informed you as much as the research process has informed me. I have learnt much throughout the research for this post which is as enjoyable as the writing itself.
If you have any questions or comments please leave me a note below.
Cheers, John
If you're interested then check out these other posts
Fujifilm's 90mm f2 lens review
Blackrapid Double Breathe harness review
The Upside to having your images stolen
Hi John,
Great article – really makes clear what’s going on with banding.
I am a Fuji unit photographer in the UK. I’ve heard from Sony shooters that the banding is little to non-existent using electric shutter for them. However, I’ve encountered problems with both my xt3 and xpro3 with certain types of light, especially fluorescence tube lights.
Are you shooting 100% Fuji on film sets? If so, how often do you realistically find banding a problem.
Thanks again for the great content,
Jack
Hey Jack,
Yes I shoot Fuji only, 2 x X-H1’s and GFX-50s for portraits both on-set and key art.
Very rarely do I have an issue with banding. There are times when it is there but you
can only really see it when you compare a number of frames shot in the same burst.
If I think there may be an issue I do a quick test and then just shoot at 1/100sec if need be.
It’s no where near enough of an issue to consider changing brands. To many things going for the Fuji
system in my opinion.
All the best
John
Hey John – great explanation. Exactly what I was looking for.
I have my first job coming up as an on set stills photographer and am concerned about banding. Are you able to shoot at or under 1/100 to avoid banding, as well as avoiding motion blur? What’s the protocol when on set – do I ask what kind of lights they’re using? I’m assuming since I’m in Canada the power will be 60hz – that means I can shoot at anything divisible evenly into 120 (120, 60, 30 eg)? Shooting with the Fuji xt2 btw. I’ll be sure to shoot some test shots first to be sure!
Btw, do you ever switch over to the mechanical shutter when noise isn’t as much of a problem on set?
Thanks,
David
Hi David,
Glad you found the article useful. To answer your questions in order. Your concerns with motion blur are valid, all you can do is be aware and work within the limits of the circumstances. Unfortunately you don’t have IBIS with the X-t2 as I do with the X-h1. With regards to protocols and asking the gaffer/electrics what lights are being used I would defer to a quick test to confirm one way or another as a more accurate answer. I always set the drive to continuous low an squirt off 5-10 frames on a wide angle lens at both 1/125 and an off speed, 1/160, 1/250. Reviewing back through the viewfinder will give you your answer immediately. Finally, yes I use the mechanical shutter whenever I can, exterior or interior. Good luck with it all. Cheers John
Hi John!
Thank you so much for this explanation!
Do you have any tutorials on how to remove the horizontal/vertical banding if it is already on your photos? I have had an associate photographer photograph a ceremony for my under cheap LED lights with a wide aperture and there is now the worst kind of rolling banding across all the images.
I’m pretty desperate so any help would be greatly appreciated!
Hi Jasmine,
I feel your pain as I was in exactly the same situation some years back and the reason I started looking into it all.
The short answer with regards to a tutorial to remove/hide the banding is, unfortunately not.
Sorry, I wish I could have been more help
All the best
John
Hi John,
Thanks this is a great explaination of what is happening when you encounter banding and how to avoid it!
Many thanks,
GC.
Appreciate the comment Gary and glad it was useful, Cheers John
Hi John, thanks for the helpful explanation! This was great to get a better understanding of my camera. Thank you!
Cheers Kevin, Thanks for the comment, all the best from DownUnder, Cheers
Thank you John, Your article is a great help. I’m using electronic shutter to preserve my shutter. Using shutter speed divisible by 100 really works. I’m using 1/10, and 1/25 whenever there are artificial lights
Thank you so much.. very clear.
Cheers Greg, glad you found it useful
Hi John, great article! Just curious why the 1/125 produces banding when 1/25 doesn’t? What about 1/200? Trying to wrap my head around this as I’m going on a film set next week with a mirror less & will be indoors. Cheers
AC or Alternating Current alternates between a positive and negative pulse, each pulse/alternation lasts 1/100sec
Add a positive and negative Alternation together and you have an cycle,
1/100sec positive Alternation plus 1/100sec Negative Alternation equals 1/50sec cycle.
Each positive/negative Alternation starts at zero volts which is black, no light.
It increases in voltage intensity to its maximum, where the light is its its brightest.
It then returns to zero.
I’ll start with 1/25 shutter speed.
Within the length of the 1/25sec shutter speed 4 Pulses/Alternations will be completed, 2 positive and 2 negative.
THE IMPORTANT THING TO REMEMBER IS THAT EACH OF THE 4 PULSES/ALTERNATIONS ARE COMPLETED.
FROM ZERO TO MAX INTENSITY AND BACK TO ZERO.
1/25 = 2 x positive 2 x negative Alternations
1/50 = 1 x positive 1x negative Alternations
1/100 = 1 positive Alternation
Any shutter speed that is faster than 1/100 is open for less time than it takes to complete a single alternation so doesn’t recieve an equal illumination
Electronic Shutters are controlled by the sensor itself. Dependent on the shutter speed a row, or rows of pixels are initiated and terminated (turned on and off)
as the electronic shutter ‘rolls’ down the sensor from top to bottom.This can take up to 1/10sec to complete.
With 1/125sec the row or rows of pixels on the sensor are open for less time than it take to complete a full Pulse/Alternation.
So as each of the rows of Pixels are opened/closed they are exposed to a different section of the sine wave receiving a varying amount of light intensity.
Over the last few years the read speed of sensors have become much faster. Reducing the amount of banding to zero in some cameras.
Test, test, test. When you get on set take some test exposures of a plain surface, white wall is perfect, with the electronic shutter at varying shutter speeds shooting at 5fps or faster .
Some times banding is there but it is very slight, if you shoot using the drive you’ll pick it up as you click thru the exposures because the bandings position on each image will change.
Hope this all helps
Cheers
John
Ah I understand – thank you this is really helpful! Very much appreciated.
Hi John, many thanks for this article. I take photos during ballet performances and often have this issue.
I need to freeze motion in my photos, which requires a shutter speed of at least 1/400s. I’m using the Fuji X-H2s, and have noticed that banding is eliminated at the shutter speeds you mentioned. But I also observed that banding is mostly not noticeable at multiples of 100, such as 1/200s and 1/400s.
Why do you think this could be possible? The X-H2s has a super fast sensor readout speed, but I’m getting the same results with my X-T4, which is much slower.
Thanks again, Admill
Hi Admill,
Yes with the speed of the layered sensor in the XH2-S we are relieved of most banding. I use two XH2-S bodies with my Unit Still Photography work and no longer have the issue. Interesting that you don’t have the issue with the XT-4.The XT-4 is the one model I skipped, going direct from the XT-3 to XH-1 so have no experience with it. Cheers, John
Thank you for the insight.
Just tried the proposed shutter speed on my Canon Eos R. Only 1/100s helped. Other multipliers, like 1/200 or 1/400 had zero effect (same intense banding).
But 1/100 speed, is hardly usable.
Hi Dimitrios,
As explained towards the end of the article
the usable shutter speeds are ones divisible evenly into 100 not multiples by 100.
It’s frustrating as 1/100 or 1/125, depending on the power supply of your location, is not particularly fast.
These days though with the advancement in sensor design and write speeds the banding is becoming less and less of a problem.
Kind regards
John
Many thanks for the education, John. I had a frightful experience with banding last night with my Sony A7R3 with 20mm f1.8 lens. The advice above should help, going forward.
I assume the lens type (wide/tele) have no impact on banding.
Hi Sandeep,
I’m glad you found the article of use. The lens focal length or aperture has nothing to do with the banding; it’s all about the shutter speed.
Cheers John