Flash Shutter Sync With Levi Sim

In Master Photography Roundtable by Jeff Harmon15 Comments

What is “Max Sync Speed?”

Max sync speed in flash photography is the fastest your shutter speed can be while still having the entire sensor of the camera open to receive light at the same time.  For most modern cameras this is somewhere between 1/160 and 1/250 but it is very specific to the make and model of your camera and you should find the “sync” speed in your users manual.

Let’s start out with trying to defining the term.  Max sync speed only matters when you are shooting flash, but let’s define “max sync speed” for photographers who have a good grasp on shutter speed but have NEVER used flash.

Shutter Like a Shower Curtain

A shutter is like two shower curtains on a single rod.  When there is no shower curtain cover the shower then light is reaching the sensor.  You start out with one of these shower curtains cover the entire shower and the other is all crumpled up to one side.  With a slow shutter speed the one curtain covering the entire shower opens up so that is is now pulled all the way to the other side so that it is now crumpled up just like the other curtain and now you can shine light into the shower and the entire shower receives all of that light.  When the time the shutter is supposed to be open has passed then the second curtain that started out all bunched up now closes so that it covers the entire shower.

There is a limit to how fast those curtains can be moved, so camera manufacturers got smart and figured out that they get a faster shutter speed look by not having the entire sensor open for light at once.  If as they started opening that first curtain to expose the sensor they also very quickly started closing that second curtain at the same time so that only a really small portion of the sensor is being exposed at a time the image looks like the shutter was moving faster than it could.

Dreaded Black Bars

When a flash pops, that single pop of light will only illuminate where it is pointed for a much smaller amount of time than the shutter speed of your camera, even when that shutter speed is at 1/8000th of a second.  As the one curtain is opening being followed closely by the other curtain closing, leaving only a very small part of the sensor exposed to receive light as the flash pops, it will only be that portion that receives that light.  

The result is something that looks like a dark bar across your photo.  If the ambient light wasn’t very bright it may look like a completely black bar across your photo.  If a photographer has never seen that before they often think that their camera is broken. See my “Help! My Photo Has a Black Bar Across It” article for an example.

What Is The Max Sync Speed For My Camera?

There isn’t a single answer to this question.  You have to find out what it is for the specific make and model of your camera.  Not all Canon cameras have the same sync speed. Not all Nikon cameras have the same sync speed.  On and on. Look for “sync” in your camera manual (search the PDF) or you can usually find it on google by searching for your camera make and model followed by the words “max sync speed”.

Example: “nikon d7200 max sync speed” (1/250 by the way).

What is “High Speed Sync”?

Now that you understand max sync speed, let’s talk about the inevitable question that comes next.  Can you overcome this limitation of a max sync speed and use flash with higher shutter speeds? Yes, it is something called “high speed sync”.  

High speed sync (HSS) is a feature available in some flashes and flash controllers.  A “smart” flash if you will. Usually HSS means they are a bit more expensive, though not always like with the fantastic Godox XPro controller and TT600 or AD200 flashes.  HSS allows your camera and the flash to work very closely together so that as that slit between the two curtains is moving over the sensor the flash will pop in smaller but very quick succession.  Like magic this supports the same level light reaching every bit of the sensor even though it isn’t exposed all at once.

This happens so fast you can’t tell if you watch it happening.  This is going on in way under a second in time and we just can’t perceive those individual pops of light.  A downside is that because the light is firing over and over without much time to pull more charge out of the batteries for the next flash and the power of the flash is impacted and your batteries will run out.

Another downside is that the flash tends to heat up significantly with all of the pops of flash.  So hot you can melt modifiers you mount to the flash.

Is High Speed Sync Required To Freeze Action?

Absolutely not!  When you are working with flash you have to think of shutter speed affecting the ambient light and aperture/ISO affecting the light from the flash.  Choose your aperture first that will help you reach your creative vision. Blurring the background becomes far less important because your background is going to be quite a bit darker than your subject that will be lit by flash, so you likely need to use a stopped down aperture like f/5.6 to f/11.

If you are shooting indoors and you use an aperture of f/11 with an ISO of 100 to 400 and your max shutter speed is only 1/160 you are still probably going to get a black picture without adding any flash.  Now remember that the whole reason there is a max sync speed in the first place is that the pop of light from the flash lasts for a very short amount of time. You can use this to your advantage because your camera only records things that are lit and your flash is going to be on for a small enough amount of time as it pops to freeze the action as if the shutter speed was faster.  

You do have to be careful with the flash power because the higher the flash power the longer the flash is on (see Jim Harmer’s awesome Flash Duration of Speedlights article) which now gives your subject more time to move and become less sharp.  If you need your flash to be brighter than you are getting with it at about ⅛ power then increase your ISO rather than turning up the power of the flash.

Having a hard time understanding this?  Maybe a hard time believing this? Put it to the test!  Set your aperture to f/11, ISO to 100, and a shutter speed of 1 second.  Set the flash power to ⅛ power. Shoot indoors, the lights can even be on.  Have somebody jump in the air and take a picture.

Is There a Situation Where High Speed Sync Is Required?

Yes.  Want to freeze action at noon with a big sun with a wide open aperture to blur the background.  You need to get to a higher shutter speed (remember that shutter controls ambient and aperture controls the light from the flash) in that scenario and high speed sync can really help out.  Though this wouldn’t be the only option because a neutral density filter could help accomplish the same thing for the most part.

What is Hyper Sync?

Mostly the same discussion, but hyper sync burns the flash longer to get light across the sensor. It’s a Pocket Wizard brand name feature, but others offer something similar. Not for speedlights, only monoblocks and packs.  The difference between high speed sync and “hyper sync” is with high speed sync the flash is popping many times as different parts of the sensor is being exposed to the light and with hyper sync the light doesn’t turn off the entire time that shutter is exposing the sensor.  

Hyper sync essentially becomes a constant light the entire time the shutter is exposing the sensor to the light.

Front and Rear Curtain Effects

We have talked in this episode about the two curtains and how it causes some challenges with flash.  You can also turn that challenge into something that can be used as a creative tool. This effect or technique we are going to talk about really only works with slower shutter speeds.  We have to name the curtains as we talk about it here because the camera settings are named this way.

The curtain that moves first to expose the sensor to light is called the first or front curtain.  The second curtain that moves to cover the sensor at the end of the exposure is called the rear or second curtain.  The terms are interchangeable.

By default, your camera comes setup to sync flash with the first or front curtain.  As you press the shutter button, if flash is being used the camera will tell it to fire as soon as the first/front curtain has moved out of the way to start the exposure.  If you have a 1 second shutter speed or a 30 second shutter speed that flash will feel like it pops as soon as you press the shutter button.

If you change your camera settings to do rear or second curtain sync it will do just the opposite.  The camera will tell the flash to fire just before it closes that second/rear curtain to end the exposure.  With rear/second curtain sync and a 30 second exposure the flash wouldn’t fire as soon as you press the shutter button.  It will fire 30 seconds after you press that shutter button.

You may be thinking, but what does it matter?  So you have the flash fire at the end of the exposure instead of the end of the exposure, the flash is still popping at a rate that is fast enough to freeze action.  Why does it matter if you have the pop of the flash at the end instead of the beginning? Trust me, this changes everything.

Yes, we went earlier over how it is that you can freeze action without a high shutter speed by leveraging the fact that the light the flash produces is on for such a short amount of time.  If your flash power is down fairly low and there isn’t much ambient light then the difference between first/front and second/rear curtain sync won’t be much. However, if you have a vision of something you want to accomplish you can have ambient light be more involved in your photo and have a much better chance at having your subject still be perfectly sharp with rear/second curtain sync.

Check out these examples from Levi.

Photo made by Levi Sim
Photo made by Levi Sim
Photo made by Levi Sim
Photo made by Levi Sim
Photo by Levi Sim

Bonus Flash Question: How Far Can You Push a One Flash Setup?

This was a question that came from avid listener and Master Photography Facebook Group member Aref Alragehi.  He asked “How far can you push a one flash setup?” Aref said that he already kind of knew the answer to this question from the course about flash you have over at Lynda.com.  For those that haven’t seen them, Levi offers 5 courses over at lynda.com.

Levi thinks that you can do pretty much everything with one light.  If you think you need two lights, you need one. If you think you need three lights, you need one.  Now this is specifically the front or the light you are shining in the face of the person. You can use a reflector to fill in some of the shadows.  You may need a light in the background to provide some rim light. You don’t need more than one light on the model.

Too many photographers get caught up in adding lights and making their shoot more complicated.  The more lights you add the harder it is to control them and the more your model(s) have to wait around for you to get it dialed in.  Spend your money on flash modifiers, travel to cool places to make photos, or getting out to a workshop or conference.


Jeff: Godox AD200 Flash Strobe ($300).  I have recommended this before, and as I use them I become more and more impressed making it worth a second recommendation.  This flash strobe is pricey. It was REALLY hard for me as a hobbyist photographer to think about spending this kind of money on a flash, but I just recently did a shoot of a group of kids headed to a Sweetheart’s dance at the High School and it was incredible to have high power and incredibly fast recycle times.  Start out in Godox with their wireless trigger and the far less expensive Godox TT600 ($65) then when you have committed to using flash it is very worth the investment to upgrade to the AD200 flash strobes.

Levi: Everything from MagMod.

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  1. I usually never go back to a site to comment on a podcast however Jeff and Levi you guys knocked this one out of the park with the info provided. I am always listening in my car while traveling to and from from work (usually 12-15 hours a week). The effects with rear curtain flash have me going crazy right now scouring the internet for more information on this. Thank you, thank you, thank you!

    By the way all of your podcasts are great but this here can really step up the little wedding photography that I do.

    Steve aka NevetsPhotography on Insta.

  2. I’ve been using off camera flash for the past two years for portraits and fashion. You’ve opened my eyes to new opportunities… great podcast. Well done!!!

  3. Enjoyed this episode — super informative. I kept pulling my car over to take notes.

    What was the name of the $40 umbrella Levi recommended during the one flash segment?


    1. Author

      Jamison, I don’t think it was a specific umbrella brand Levi was referring to there, as far as umbrellas go they are all about the same and his point was you don’t have to spend a lot of money on them. Get an inexpensive one and get shooting!

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  8. I revisited this pod cast, to refresh my knowledge on flash
    Maybe they can do a pod cast on strobe photography using speed lights
    I have used mine and got some brill effects

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