Understand Flash Sync Speed so You Don’t Sink Your Photo Shoot

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A Guest post by Marlene Hielema from www.imagemaven.com.

Several years ago I borrowed my piano teacher’s grande piano and her lovely home for a portrait shoot of an up-and-coming pianist. As I set up my studio strobe lights for the shoot I was inspired by Arnold Newman’s iconic photo of Igor Stravinsky that I had recently seen at a gallery. I wanted to use the piano as a design element, just like Newman did.

The shoot began with my usual warm up roll of film. Just like Newman, I was shooting in black and white. By the end of the session I had shot five rolls of 36-exposure film. I couldn’t wait to get into the darkroom to process it. When I hung my film up to dry, much to my horror, four of the film rolls had thick black bars running across the them. My heart sank.

Somehow when I changed film after my warm-up roll, I must have accidentally caught my thumb on the shutter speed dial and set it on a different shutter speed than what I had started with. In all the excitement I hadn’t noticed.

This can happen with digital photos too

Black bands like this are caused by the shutter curtain blocking part of your image during the exposure. If you use studio flash or other off-camera flash systems, you might have had this happen to you, and didn’t know the cause. Let me explain.

Focal plane shutters

dSLR cameras use a focal plane shutter which sits right in front of the sensor. A focal plane shutter consists of two curtains that travel from top to bottom that open to reveal the sensor. Think of a wipe transition that you might see in a slide show. In the case of an SLR camera, there are two wipes. One curtain follows the other. The longer your shutter speed is, the more time it takes for the curtains to travel down the sensor.

Why black bands happen

It takes the average focal plane shutter in today’s cameras about 1/200 second to travel down the height of the sensor. Since a studio strobe (flash) is instantaneous by comparison, you have to make sure your shutter is all the way open when the flash fires. If not, you’ll catch a black bar across your photo. The faster the shutter speed, the more black you’ll get in your photo. See the samples here to compare. (Ed note: Put photo sequence in here in this order 1/200s, 1/250s, 1/320s. 1/500s)

If your shutter speed is too fast, then you’ll miss your chance

At some point curtain number one is finished travelling down the focal plane, and curtain number two has not yet started, revealing the whole sensor. That is the point in time at which the flash needs to fire, or you will end up with black bars when one of the curtains covers part of the sensor. See the animation below for a demonstration.

Sync speed to the rescue

In order to avoid this problem you need to shoot at, or below, your flash synchronization speed. For Canons the sync speed is 1/200s. For Nikons, 1/250s.

Changing to a slower shutter speed will not change the exposure because in the studio when you’re using flash, the ambient light is usually so low that it doesn’t register. Of course there are limits. A really long shutter speed such as 1 second or more, will most likely take in the ambient light coming from the modelling lights, and that will affect how your photo looks as well as the white balance.

On-camera flash (i.e. Speedlight)

Your on-camera flash won’t let you set a shutter speed higher than your sync speed. However, some on-camera flash systems have a setting for high speed sync. In other words you can set a faster shutter speed than the normal sync speed. This setting is useful if you’re using flash outdoors because sometimes 1/200s is too slow a shutter speed, and will result in overexposure on a very bright day even at f22.

High speed sync sends several pulses of lower intensity light as the curtains travel across the focal plane, instead of the usual big burst a studio flash makes. Using high speed sync is also useful in situations where you want shallow depth of field, or fill light, if using flash outdoors

Still shooting film?

If you’re using an older (pre electronic) SLR film camera, the shutter probably travels sideways instead of top to bottom. You can check that by opening the back of the camera, without any film in it, and crank the film advance lever. You’ll see the curtains travel across the focal plane as you reset them. In older sideways shutter cameras the distance the curtains have to travel is longer (the long side of the film instead of the short side) so your sync speed will have to be longer too. For Canons, 1/60s and for Nikons, 1/90s.

Why do these photos show the bands moving from bottom to top if the shutter is traveling from top to bottom?

Your image is actually upside down and backwards when it hits the sensor or film, but you view it right side up and the right way around because of the prism built into your SLR camera. I thought I’d put these photos in here the right way up for this demonstration to avoid confusion.

sync-200.jpg

sync-250.jpg

sync-320.jpg

sync-500.jpg

You never make this mistake twice!

I learned this lesson the hard way after blowing my portrait shoot many years ago. In the days of film I didn’t have the luxury of immediate image playback. The importance of flash synchronization is forever burned in my brain.

About the Author: Marlene Hielema

marlene-hielema-avatar.jpg
My creativity is maxed out when I’m helping people solve their technical problems, especially those involving digital photography. I’m not woo woo or a fine artist, but I get a great deal of joy teaching creative people about the technology of digital photography, and watching how that understanding opens the doors to their creativity.

I teach photography and Photoshop online, in the classroom, for corporate workshops and one-to-one. I’m a camera raw evangelist. I’ve worked with kids, artists, engineers, doctors, and designers, and I’ve helped many photographers in their transition from film to digital. Find out more about what I can help you with at www.imagemaven.com and then let’s connect via Twitter and Facebook.

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  • Ashish

    I want to understand it in respect on my camera
    I am using canon 7d and youghnou 685 on camera flash, i was expecting same result as described above when i triggered on camera flash @1/8000 of a sec without HSS. but surprisingly result was just fair, flash illuminated my subject and background with no shutter blockage. result was same as it is shown in above pic with 1/200th of sec. can u please tell me why this happened thanks in advance

  • Sixto Garcia

    The reason that it matters is this. To achieve a faster shutter speed above 1/250 of a second on a Nikon camera, the second curtain does not wait for the first curtain to travel all the way down. The second curtain starts moving before the first curtain finishes its full movement down. The effect of this is that the entire sensor is exposed to light however its a slit of light moving across the full sensor. So your flash happens in less time…. and only the slit created by the front and back curtain gets exposed. The flash of light is much brighter than the ambient light and thus the parts of the sensor still covered are not exposed in that instant leaving black bars.

    At 1/250 of a second and less this does not happen because the mechanical mechanism that moves the shutter is fast enough to expose the entire sensor. The first curtain opens up all the way, the sensor is exposed fully to the lens image, then the second curtain closes ending further exposure of the sensor.

Some Older Comments

  • Patti September 16, 2013 09:23 pm

    I cannot thank you enough for this post. I DID IN FACT BLOW my portrait session due to this. It happened a few other times, but it was occasional. I was going nuts! Trying to figure out what I did wrong. I even called our local camera shop and he thought it was the positioning of my umbrellas, which I had thought for sure too, until one instance it happened, I didn't move or touch anything EXCEPT for the shutter speed! I went crazy. I even switched lenses and camera bodies (had the same setting for the other camera too) I almost went out and purchased new lights. I googled it and I knew it had something to do with shutter speed, but no other site explained it in "Patti terms" as I say. I just need a little easier breakdown of it and you nailed it. Thank you so very much for your explanation and your site is wonderful! Will be stopping here more often :) Thank you thank you I can't thank you enough!

  • GT August 25, 2013 04:31 am

    I have exactly the same problem, but it's happening even when I'm not using flash. When I shoot outdoor most of my pictures now has the black band at the bottom. Only recently the problem occurred. Is my camera's shutter having some problem since flash speed is not then culprit?

  • Steve February 28, 2013 06:50 pm

    Expanding on this a bit further: My Nikon D7000 has an "e1 Flash sync speed" menu option that appears to be independent of the shutter speed setting. I got my hand on an old Photogenic studio strobe setup and was getting dark photos even with a shutter speed of 1/30. This completely baffled me until I found the Flash sync speed setting which was set to 1/250... dropping this down to 1/125 solved the problem.

    What the heck is going on here? My theory, since I have found no technical explanation of what the "e1 Flash sync speed" option is actually changing, is there is the mechanical shutter controlled by the shutter speed setting and there is an electronic shutter controlled by the "e1 Flash sync speed" setting.

    My theory MUST be wrong though or the D7000 could never have a shutter speed longer than the "e1 Flash sync speed" setting...

    If anyone has an explanation of what's going on here I would love to hear it...

  • chasrl178 June 11, 2011 08:04 pm

    If you would like to research this it is called high speed sync and the shutter can go as high as 1/8000 but the strength of the flash is reduced. I know Nikon and Cannon have this available you have to educate your self on how to use it . Have a lot of fun trying this.

  • Chuck June 11, 2011 12:51 am

    I am not sure about Canon or Nikon, but with my Pentax K-x the only way to fire off camera strobes is via a radio transmitter to receiver slaves, with a sync cord plugged into the camera or optical slaves via the on-camera flash or one mounted on the hotshoe. I cannot plug a sync cord into the camera without using a connection (such as a safe sync on the hotshoe) as there is none built into the camera. Therefore the highest shutter sync speed is protecting my work. There is a built in safety on the hotshoe, whenever a flash or safe sync is slid into the hotshoe, a button is depressed which prevents the flash from firing at any speed above the shutter sync speed. Also, if the built in flash is used to optically trigger strobes, it will not fire above the highest shutter sync speed. It is a nice feature that apparently Canon and Nikon have circumvented by placing a pc outlet into their cameras (at least some of them).

  • Chris June 10, 2011 12:11 pm

    People forget that with ETTL in Canon you can still acheive 1/1000 sync speeds. Its called high speed sync (hss)

  • John Parli Photo June 10, 2011 04:17 am

    Don't throw it all out the window and let the sync speed necessarily limit you however... if drastic times call for drastic measures and you need just a touch more shutter speed over what your camera's sync will allow simply recompose, taking the shutter banding issue into account and crop your shot later in post. Provides you with that little bit of wiggle room if that's what you need.

  • John Parli Photo June 10, 2011 04:16 am

    Don't throw it all out the window and let the sync speed necessarily limit you however... if drastic times call for drastic measures and you need just a touch more shutter speed over what your camera's sync will allow simply recompose, taking the shutter banding issue into account and crop your shot later in post. Provides you with that little bit of wiggle room if that's what you need.

  • Andrew Conway June 10, 2011 03:21 am

    Thanks so much for putting some great basic light on this subject because its my current problem with shooting outside into the sun. I'm shooting at 640th of a second right now

  • Eric June 10, 2011 01:28 am

    I miss my D40. I wish I hadn't sold it. Aside from the great sync speed, it was just a fun, lightweight camera in general.

    I don't really do much with portrait work and I have never had a problem with flash sync with the few portrait shoots I've done, but this is great information and one of the most informative articles I have read on here!

  • Jakub June 9, 2011 11:49 am

    Did I miss it or is the article completely omitting the point that a solution to these issues is to have a camera supporting leaf shutter lenses? For example Phase One 645DF medium format camera with an IQ140 digital back can perfectly sync flash up to 1/1600s with Schneider Leaf shutter lenses.

    I am aware that this blog is mostly aimed at beginners and amateurs, but it would be nice to actually hint at some other systems to give its readers a full understanding of the issue and possible solutions....

  • Sally June 9, 2011 12:57 am

    Interesting...would love a faster synch speed to capture those action shots in the studio...come on Canon, keep up with Nikon!

  • Dima June 8, 2011 11:38 pm

    Canon Rebels sync up to 1/200s, all Canon lines above XXXD (XXD, XD) allow for 1/250s sync.

  • spence June 8, 2011 03:50 am

    as jeremy said, sync speed is not 1/200 for all canons. Sync speed is not brand dependent but more based on models, Usually the better the camera the higher the sync speed goes, however some cameras (like the Nikon D40) had really fast sync speeds (1/500 and some claim up to 1/1250). If needed sometimes I shoot with a faster speed than my native sync speed would be with the intention to crop out the black band. As one gets more comfortable with their camera/flash it becomes more and more intuitive.

  • Marlene Hielema June 8, 2011 03:26 am

    Good to know Jeremy! Thanks for adding this info.

  • Scott E. Detweiler June 8, 2011 02:47 am

    As a tip, you can always hold the camera upside-down so the "un-flashed" portion of the image is above the head of the subject. If the sky is the only think not being flashed, it would not show up anyway.

  • Neeraj June 8, 2011 02:45 am

    I was thinking about this and what I don't understand is why is there a mechanical shutter in a digital camera. Wouldn't a digital shutter be more effective. You would have ultra fast shutter and no shutter curtain, no mechanical moving parts lots of other benefits. If they can make it work on video cameras I am pretty sure they can do it in dSLR's. May be they already have it they just want to milk everthying out to the old technology before they put that one out. May be I should file a patent, I could be rich. ;)

  • Brian Dougher June 8, 2011 02:13 am

    The max sync speed is not 1/250 for ALL Nikon cameras (I don't know about Canon). For example the max sync speed on my Nikon D40 in TTL is 1/500. With wireless triggers I can get up to 1/1000. This is true with the D70, D70S, D50 and D40 because they all use an electronic shutter. Just one of the reasons I will never give up my D40.

  • Jeremy June 8, 2011 02:02 am

    FYI, not all Canon's are at 1/200. The Canon 7D is at 1/250 and the 1D M3/M4 are both at 1/300.

  • sillyxone June 8, 2011 01:53 am

    this is one of the strength of the Nikon D40. Although relatively inexpensive, it has a sync speed of 1/500. My daughter and I had a lot of fun with the "flying/freezing-in-the-air" photos in our bedroom.

  • javan June 8, 2011 12:54 am

    After being a film shooter for 20 years, I carefully researched the ins and outs of digital cameras and studio lights before my first shoot my digital camera. I made sure that I had a new digital slave that would not trigger my strobes when the preflash went off. When I shot my first shot I was horrified that part of the image seemed overexposed. I spent several panicky minutes trying to track down the problem and several shots later i realized that my shutter speed was too fast and my apeture too big. The whole image was actually overexposed and the banded part looked ok. So, thanks to the digital transition I actually did make this mistake twice (the first time was twenty years earlier the first time I used off camera lighting). Fortunately with digital, you can correct the mistake before it gets embarassing and costly.

  • Erik Kerstenbeck June 8, 2011 12:54 am

    Hi

    Once again a great reminder about synch speed. I have made this error myself, but now I use a tethered LCD Monitor for all of my Studio work. Not only does this help me catch oversights like this, but allows immediate feedback to the models. This is beats showing the small capture on the camera back, and helps the models to adjust quickly!

    http://kerstenbeckphotoart.wordpress.com/2011/03/06/red-or-black-ii/

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