How Shutter Speed and Aperture Relate to Flash

This illuminating tutorial is guaranteed help you take better photos.

In this information-packed photography class, Karl breaks down the relationships between flash power, aperture settings and shutter speeds.

You’ll learn about:

  • Understanding flash sync speeds
  • The relationship between ambient light and flash
  • The relationship between aperture and flash
  • First- and second-curtain flash synchronization

You’ll learn how each of these can work together to influence the final image.

In this class:

  • How shutter speed works in photography
  • Sync speed vs flash duration
  • Leaf shutter vs focal plane shutter
  • Shutter speed and aperture
  • The impact of ambient light on an image
  • Controlling flash exposure
  • Combining studio and ambient light

If you enjoy this class, check out Understanding Flash Power and Fast-Flash Jelly Headshots.

Questions? Please post them in the comments section below.

Comments

  1. Hi Karl, my apologies in advance for the silly question; I am still a neophyte. I was wondering why a shorter shutter speed would not allow ambient light in. When you shot the photo of Stephanie at 1/60 of a second, the camera only recorded flashlight. However, if you had shot with no flash at that same speed, the camera would have recorded some ambient light. Probably it would have resulted in an underexposed shot, yet some ambient light would be captured. I must have misunderstood something from your explanation.
    Thanks for the answer and most of all for the outstanding course!!

    1. Hi Max, It would also depend on the aperture. Remember the aperture also dramatically affects the amount of ambient light coming in. So 1/60th at f8 might not let any ambient light in to the camera (in an indoors situation where the light isn’t as bright as outside) but 1/60th at f1.8 would let some ambient light in. The best way to find out is simply do a test shot without the flash trigger to see if any ambient light shows up. Generally speaking though it’s always better to go with the fastest shutter speed you can (that’s called the cameras sync speed) and use that to cut out as much ambient as possible. If you find that even with the fastest sync speed and the desired aperture that you still have ambient light pollution then you must reduce the ambient light pollution.

  2. Hi Karl! Love the way you teach. I just have one question from this class, just to check if I understood everything: If I want to shoot some portraits with movement (someone dancing for example), I can do that with a slow speed on camera if I don’t have ambient light? With natural light I always shoot with high speed, but in studio, is the flash doing that work? Thank you

  3. Hi Karl, the lesson was super clear, I just have one question, what is the difference between High speed sync and Hypersync flash photography? thank you for your time!

  4. Head rush Karl, so easy to understand. I have asked many people to explain this and you made it simple. Thank you

  5. hrachess

    Karl, after watching this whole course, I still have one question (sorry if it sounds little stupid). So I understand that making shutter speed slower in studio while using strobes, just allows more ambient light. But my questions is following. Let’s say you shoot outdoor with 1/10th of even slower shutter speed and hand held, you will most probably get not that sharp images right? so if you do the same but in studio, where is no ambient light, all dark, just a strobe light, but again hand held and slower shutter speed, won’t it have an influence on the sharpness of the image??
    I understand that it’s just burst a of a speed light which is very quick, but if camera is hand held and shutter is still open, won’t it make little blurrier picture? or it will be exactly as sharp as it’s when 1/5th, 1/100 or 1/800… ?
    The reason I’m asking is because I want to understand, in case of shooting water splash or falling object in studio, what real difference will be in terms of shutter speed changes, considering no any ambient light…
    Thanks in advance,
    Hrach

    1. Hi, if you shot in a very dark studio with a fast flash and a slow shutter speed then you could shoot hand held at 1/15th if you wanted to and it wouldn’t make any difference because there was no ambient light to be recorded. The flash would freeze everything but your composition might be poor because you couldn’t see what you were shooting. If it was totally black in your studio it wouldn’t even matter if your shutter speed was 5 seconds long because no light is no light, the only light is the burst of flash which fires with a short duration freezing your subject. However we don’t often work in totally black studios, so it’s always advisable to take a test shot without the flash trigger to see if your camera recorded anything.

      1. hrachess

        Thanks Karl. Just wanted to make sure that I understand the theoretical part correctly, as I don’t have that much experience and tests with studio lights.. Appreciate the answer and your time.

  6. derrick_connell

    My brain hurts but my heart is singing!

    The insights on both high speed sync and second curtain sync are phenomenal. I am off to test both out. I love the effect of the second curtain sync.

  7. Hi Karl!
    I was wondering… in what cases would I need a faster shutter speed (and as a consequence choose first or second curtain) if the freezing motion is based on the speed of the flash?
    Thanks

    1. Hi HC, you don’t need a fast shutter speed if using high speed flash, you can use any shutter speed (up to the sync speed) even very slow shutter speeds as long as you are shooting in a darkish room.

        1. Where you are shooting in a bright room with lots of other light or where you’re modelling lights are on full brightness.

  8. Excellent as usual….I think this is the 5th one I’ve watched in a row! LOL. You stated that HSS is a “work around” for higher shutter speeds. I understand the downside as speed light battery consumption will be quicker. What are the other downsides to it? Color balance issues? Ambient light pollution? Thanks!

    Arjun

    1. Hi Arjun, the main disadvantage is that for HSS to work the flash is actually using longer burn time flash bursts, so usually near full power and there is not much control over the flash power from the flash itself. This has to be done from the camera which reduces the versatility a little.

  9. If a camera doesn’t have a 2nd sync option, is there a way around this? Perhaps and external flash with that setting?

  10. Hi Karl, very clear explanation! Can I confirm that I will also need a HSS enabled flash head aswell as a HSS trigger. So for example I won’t be able to use my old Profoto 600’s to synch above the camera synch even if I swap out my old wireless trigger for a new HSS trigger? Thanks Steve

    1. Hi Steve, yes my understanding is that is correct. I’ve only used HSS once to demo on a broncolor siros ‘how to’ video so I’m afraid I’m not an expert on it. But from what I understand the flash burst actually becomes longer so that light is exposing for the entire time the small slit of 1/8000th passes over the entire sensor. To do this requires the flash in a HSS setting and a capable trigger.

  11. Hi Karl,

    Quick question. I just bought some cheap Interfit studio flashlights with soft boxes. Apparently my camera supports 1/200 sync speed. However, when I choose that shutter speed I can still see the shutter towards the bottom of the image, takes up a bit less than a third of the image. Of course, if I slow the speed down then I don’t have that issue.

    So my question is, am I doing something wrong? The camera definitely supports 1/200 sync speed but it seems I need to make it slower.

    1. Hi Chris, you’re camera is either not supporting 1/200th or the triggering method has a delay problem. I would expect it’s the first, I once had a Canon 5D that was supposed to be 1/200th and I could only ever get it to sync at 1/160th.

      1. Thanks Karl. It seems I have to set mine to 1/125s. There’s a part of me that thinks it’s maybe the trigger as they are not overly expensive lights, this was also on max power so I might try reducing the flash power to see if that makes a difference. Maybe if I try some proper studio lights in the future I might get my answer. Thanks again for responding.

        1. Hi Chris, try an actual sync cable from the camera direct to the lights to figure out if it’s the trigger.

          1. Good point, thanks Karl, that would definitely be the fastest way to check!

  13. Hello Karl,

    I just want to say that I am absolutely flabbergasted by your online training course. It is amazing. I have learned so much in such a short time.
    That is by far the best money I ever spent. Just like you said in your advert, first invest in yourself and then in your equipment..

    Thanks Karl,

    Keep em coming..

      1. Hello Karl, yesterday during my self portrait shoot I ran into the problem you explained in detail regarding flash sync speed. I was shooting with a fast shutter speed to eliminate the ambient light and I just wanted to light up my face with the flash using the inverse square law. During the shoot I just wasn’t able the see the bottom of my face, it was always dark and then it hit me, I remember your course on sync speed. I was shooting at a shutter speed of 400, and then I found out that my max speed without a high speed flash sync is 320. So I adjusted my f-spot, shallow depth of field had no use here as my back ground was all black. And then I got it to work. Thanks again, I would of never figured that out without seeing your course.

  14. Hi Karl, really loving the courses so far thank you! Does changing the aperture to increase or decrease the flash power then have an effect on the depth of field / background blur?

  15. Hi Karl! I hope you & your team are staying safe due to this hard times. Well, I have a question for you. I have a high sync speed trigger (according to manufacturer 1/8000s), do I have to change trigger in order to let some ambient light in or just a slower shutter speed with same trigger will do? Thank you in advance.

    1. Hi, thank you I hope you are well too. This is one of those questions where I’m afraid you will just have to try it and see. Sometimes 1/8000th is going to be much too fast when you are trying to combine flash with daylight because you will loose all the daylight. Other times you may be in the studio only trying to shoot some fast motion and then it will be fine. But the simplest way of finding out is to take your camera outdoors and put it on a tripod, set up your flash and trigger and just play with it and make a note of each result on a note pad while you test a series of shots and then keep those shots on file for future reference. Have an object such in the 3m range and then look at the results of the light on the object and the further (daylight) background at different settings.

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