Video tutorial – High Speed Flash Sync (HSS)
High Speed Flash Sync is a topic we have covered several times over time here. With this tutorial though, I wanted to visually run through the settings and discuss the implications of the settings, and what we see on the back of our flash. There is a certain consistency here that will help us evade guesswork, and that will help bring a systematic approach to our flash photography. So here it is — a video tutorial on High Speed Flash Sync. As always, I welcome questions and further discussion in the comments.
Two of the previous articles where I tried to dispel some of the notions about HSS:
Mostly, I want to dispel the idea that we use High-Speed Flash Sync to overcome bright sunlight. You hear such general (misguided) advice that the faster shutter speed helps “kill” the ambient light … as if it doesn’t affect the flash output.
The idea with this video is that you have your camera (with flash) in hand, and then run through the settings to see how your choice of shutter speed and aperture (and ISO) affect your flash output.
One of the assumptions with this video, is that you have a larger speedlight that shows you details such as the distance that your flash can reach. This is essential in understanding what is happening with your flash output as you change your settings.
On-Camera Flash Photography – revised edition
This book is explains a cohesive and thorough approach to getting the best from your on-camera speedlight.
Particular care was taken to present it all with a logical flow that will help any photographer attain a better understanding of flash photography.
You can either purchase a copy via Amazon USA and Amazon UK, or can be ordered through Barnes & Nobles and other bookstores. The book is also available on the Apple iBook Store, as well as Amazon Kindle. Also check out the Amazon Kindle store.
Learn more about how the cover image was shot.
Summary
One of the key ideas in this tutorial, is to show how shutter speed becomes (approximately) a linear control of your flash exposure once you go into HSS territory. You do lose a fair amount of flash output, but the relationship between your flash exposure and choice of shutter speed is then linear.
In other words, as you change from 1/1000 @ f/4 to 1/2000 @ f/2.8 … your flash exposure should remain constant. No need to adjust accordingly.
This is one of the fundamental differences between the flash’s output during normal flash sync and HSS. And you can confirm all of this for yourself, camera in hand. That’s the best way to learn.
Related articles
- tutorial: High-speed flash sync (HSS)
- When to use high speed flash sync (HSS)
- How to overpower bright sunlight with on-camera flash
- Tutorial: How to use the guide number of your flash
- Portraits with shallow DoF & high-speed sync flash
- Practical tutorial: Controls for manual flash exposure
- When aperture does NOT control flash exposure
- Manual flash vs. TTL flash
Watching this was like eating a deconstructed fine dish. Everything is delivered separate but when put together as you have served us, it makes delicious sense.
If I may offer one suggestion, as you are changing the shutter speeds to illustrate the linear outcome, it may be helpful and allow the viewer to follow along better if you also infuse the shutter speed setting on the screen while making those adjustments.
Thanks Neil, your content is always outstanding.
All the best,
Joe
Excellent tutorial. Very well explained, at a great and easy to follow pace, without any confusing additions.
Very helpful Neil, very good info and nicely delivered. So simple, sunny 16 for flash.
One question I have is, when bouncing would you ever use manual flash with these calculation for the sake of consistency if you were getting unpredictable results on a job using ETTL. And if so is it just estimating the total distance to ceiling/wall and on to subject or is some light lost during the bounce? Thanks Gary
With bounce flash I am usually in TTL mode, because I move around at events.
There is one exception — most flashes in my experience, don’t quite push full power when in TTL mode. They all seem to taper off the output, and tend to under-expose when you really need all the juice it can offer.
For that reason, when I need full power, or close to full power from my speedlight when I bounce my flash in large venues, I tend to be in manual exposure mode for my flash.
Neil – I’m glad to hear this about manual flash. With the type of events I shoot, I don’t think I am EVER in ETTL mode. Usually manual at 1/2 to full power. I thought I was doing something wrong, but I seem to always need the flash power.
Wonderful video explanation Neil, thank you. I’ve already had an idea how it works, but now it is completely clear for me. :-)
Neil,
I was confused by the “linear” relationship between shutter time (above sync speed) and exposure as you demonstrated it. Everything stayed the same on screen so how could it be a linear relation. Then I realized you changed the aperture to compensate for each change in shutter speed. I think the linear relation description is made clearer by looking at the distance chart on the flash as you then change shutter speed, again for values faster than sync speed.
I have both a Godox V1 and 860VII. The guide numbers are each different and quoted at different focal lengths (they give full power values only and don’t specify flash zoom). To make a similar comparison to your presentation set your camera shutter to 1/250, ISO 100, f/11, adjust the flash power to 1/1 and vary flash zoom until the exposure distance reads 10 ft. In the case of my V1 I had to go to max zoom, 69 mm to get the distance to read 10 ft. so the V1 flash has a GN of 110 at 69mm zoom. The manual specifies 92 at 50mm zoom.
As an amateur I don’t get sufficient practice to keep all this stuff in my head. Great presentation. Old fan from BFT days.
This lesson was so helpful! Thanks !
Thanks! Years ago I bought a flash to make pictures of dresses my wive made. And I did not know what I did. But then I found your website. Your tutorials are great!
Hi Niel
First great video , What happens when you have a off camera flash that is capable of HSS ?
Is it just a guessing game at that point .
Matrix Photo
Lou — no! It’s not a guessing game anymore. That’s the entire message in this tutorial video. Check the last section on the video — you need to remember one or two (or three) combinations of settings.
If your flash says you need to be 7 ft from your subject in bright sunlight, at f/5.6 when you are at 1/1000 … then that’s what it will be. It is fixed.
Now the beauty of the flash output being linear regarding shutter speed / aperture combination, is that it is the same for f/4 and 1/2000
Whether the flash is ON your camera, or OFF your camera, the flash power / distance / aperture / ISO combination remains consistent.
Hi Neil, it’s very refreshing to see what happens as soon as we go beyond max sync speed! No speculations, just facts! Kudo!
I followed each of your steps with may camera and flash (Canon 7D + 600RT) and experimented a little bit myself and some results looked even worse of what you showed.
The following are my findings.
At ISO 100 f10 1/250 with flash at full power zoomed at 35mm the distance showed by the flash is 15 feet
At ISO 100 f10 1/320 with flash at full power zoomed at 35mm the distance showed by the flash is 5 feet (one third!)
If my calculations are correct, 3 times the distance is 1/9 of brightness, that is more that 3 stops of light, at least is this case.
I was familiar with your work from the videos using the Profoto A1. Today I followed the post on the Profoto Facebook page from the photographer who asked for advice and then continued to argue with you about your analysis.
In many years of photography, this is probably the best analysis and explanation that I have encountered explaining the entire relationship of the flash exposure “rectangle”, manual flash, TTL, HSS, guide number, etc. and how they are inseparably linked. Great job!
Excellent video, Neil! Your explanation of the relationship between shutter speed and flash output, when in maximum sync speed versus high-speed sync, is fabulous. I know that the flash power drops significantly in HSS, but knowing why that happens, and how to adjust once you hit HSS, was a bit of a guess. I’ve got it now!
In a stressful situation with lots of people waiting for you to take photos, what you need is the ability to just get out of the starting blocks. Your tip about f11, 10′, and ISO 100 provides that nudge to get you moving. Thank you for making this often-confusing topic much easier to understand. :-)
very helpful sir Neil vN
Neil,
Thank you for such an informative and helpful tutorial. To provide such information with no other remit than education is the mark of a true educator.
Will be following you from now. Great job.
David
Thanks for the video, you have just cleared some muddy waters for, Abby Medieval Festival here I come.