When teaching new Speeliters how to dim the sun with High-Speed Sync (which I wrote about here in Part One), the question is often asked “why not just shoot at the normal sync speed with a really small aperture so that you can use regular flash?” My response is “you should go out and try.” [This article, by the way, also applies to all types of flash that won't work with your camera in High-Speed Sync: third-party speedlights, monolights and location/studio strobes.]
As a reminder, here’s the short version of sync speed: it is the fastest shutter speed at which you can nornally shoot flash. In a DSLR, the sync speed is limited to 1/200″ or so because the shutter is comprised of two curtains in front of the sensor—the first-curtain being fully closed and the second-curtain being fully open when the camera is ready to fire. In order for the flash to illuminate the entire sensor, it has to fire after the first-curtain has completely opened and before the second-curtain begins to close. That defines the sync speed. If you shoot faster than the sync speed, then the second-curtain will be covering some of the sensor and you’ll have a dark bar along one edge of the frame.
So, if you want to stay in normal flash mode, your shutter speed is limited to the sync speed. On my 5DM2, that’s 1/200″. Unless you are shooting a 1D-series camera, your sync speed is probably 1/200″ too.
If your shutter speed is capped by the sync speed, then you can only dim the ambient light via the aperture. O.K., so how dark will it be if I shoot at 1/200″ and f/22. Let’s head outside at high noon and see what it looks like.
On a warm spring day in California, with the sun straight overhead, my faithful Minolta Flashmeter IVF tells me that the ambient sunlight measures EV15. At ISO 100, EV15 equates to f/22 at 1/50″. That sounds good. If the metered shutter speed is 1/50″, then I have two additional stops (1/100″ and 1/200″) of shutter speed that I can use to dim the ambient. Along the way to shooting a series of demo shot, because I’m always curious, I started the series at one-stop brighter than the meter suggested. So the first frame below is ISO 100, f/22 at 1/25″. Then I increased the shutter speed in one-stop increments (-1EV) until I got to the sync speed for my camera.
Meter +1EV = f/22 at 1/25". Some of the details in Tony's shirt has blown out, but not too much.
As metered: f/22 at 1/50". This clearly shows how the camera is compressing the shadow detail.
Meter -1EV = f/22 at 1/100". Just a stop on the path, not really usable for anything.
Meter -2EV = f/22 at 1/200". This is as dark as midday will get when limited to my sync speed.
There you have it—the photo above is the darkest I can render the ambient light when limited by my sync speed of 1/200“. Is it dark enough? That depends upon your vision. As I see it, the answer is “no, it’s not dark enough.” If I’m going to dim the sun, I want to make it darker than this. So I continued my one-stop changes in shutter speed: 1/400″, 1/800″, 1/1600″, 1/3200″, and 1/6400″. On my screen, I can see a hint of the white van in the shot at 1/3200″. At 1/6400″, the frame is completely black.
Meter -3EV = f/22 at 1/400". I would have to use High-Speed Sync from here on.
Meter -4EV = f/22 at 1/800". This is typical of where I end up (read why below).
Meter -5EV = f/22 at 1/1600". Really dark, can barely see Tony's shirt.
Meter -6EV = f/22 at 1/3200". Just a faint hint of the car.
Meter -7EV = f/22 at 1/6400". Completely black.
Why I avoid f/22 when I can
For all practical purposes, I use the widest aperture that I can to get the depth of field that I need. Stopping down beyond that aperture for the sake of controlling ambient light should be avoided. Why? Depth of field is really an illusion. In an optical sense all that is happening is that ‘circles of confusion’ are getting smaller. When CoCs are small an image appears to be in focus because we cannot distinguish the blur. Thanks to physics, what this also means is that, much beyond f/11, the sharpness of the image degrades significantly. So, while f/22 might make an image appear to have more depth of field, when you enlarge that image you’ll see that it was just an optical illusion.
For aesthetic reasons, as well as optical reasons, I typically try to stay under f/11. Look at the images above and go three frames back up the line from the bottom. The frame ‘Meter -4EV’ is what I want my ambient exposure to look like—f/22 at 1/800″. But, I want to shoot at an aperture wider than f/11. So, let’s count backwards from f/22 to f/8: f/22 > f/16 > f/11 > f/8. That’s 3-stops. By opening up my lens from f/22 to f/8, I have to stop the shutter down 3-stops in order to maintain the same amount of ambient: 1/800″ > 1/1600″ > 1/3200″ > 1/6400″.
So essentially at midday, without using an excessively small aperture, I can get to 1/6400″ at f/8. This is enough to dim the sun with my shutter so that it looks like a moonlit night. Details about the location and the background will disappear. It’s no longer the outside of my house with a couple of cars and a pre-teen son. It’s whatever I want to make of it. As a Speedliter, I can come in with my lights, modifiers, and such to create an image that expresses my vision.
Now, to get back to the fast shutter/tiny aperture vs. High-Speed Sync question, as I mentioned in Part One, switching the Speedlite into high-speed sync costs me about 2.5 stops of power. That’s o.k. with me. I’d rather have the creative freedom to control the ambient with my shutter than to accept the limitations imposed by a sync speed of 1/200″.
32 Responses to Dimming The Sun With High-Speed Sync: Part Two
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Yet another great article about why HSS is so useful. Ever since I read the article when you used 12 canon 580s I feel I need more of them…
However, i'd make a slight correction: "Unless you are shooting a 1D-series camera, your sync speed is probably 1/200″ too."
The 50D (and 40D) sync speed is rated at 1/250", although I admit I did not put it to the test, and some people say it may actually sync only at slower shutter speeds. On the 7D it's also rated at 1/250", but I've successfully tested it to 1/320".
Mihai – Thanks for the thoughts on other sync speeds. Some many models, so many specs. You're right, all the APS-C sensor camera you listed have a spec'd sync speed of 1/250".
Always best to test. I've found that they vary even within the same model. One of my 5Ds would never truly sync over 1/160".
With your 7D at 1/320", how did you do that? I'm guessing via a radio trigger or PC-cord. In my experience, a Canon DSLR will not exceed the sync speed if it can sense that a Speedlite is attached. Curious to know the details.
Great posts Syl. One thing I've always wondered with ETTL is how much flash was outputted. Why isn't that information part of the exif data of the image? (Or maybe it is, and I can't find it). It would be sooo useful to know if a flash is firing at 1/16 vs 1/8.
Kevin – As far as I know, there is not metadata on the E-TTL power level. Absolutely agree that it would be helpful to know this, in hindisght. If you need to know up front so that you can learn what 1/1 looks like vs. 1/32, then shoot in Manual.
Yes, you are right, if the camera senses the ETTL flash (be it mounted directly on the camera or using an off-camera cord), my 7D will not allow shutter speeds faster than 1/250" for anything in the world.
For the situation I described, I used a pair of Paul C Buff CST/CSRB wireless trigger/receiver and a 580ex II.
Tried the combination at different shutter speeds, and at 1/320", the flash illuminated the whole frame, without the black band that would appear on the bottom of the image. At 1/400" the band appeared, but it was less than 20% of the image, so the image would still be usable depending on lighting situation.
Maybe I have a better 7D because it syncs at 1/320, I know people have mixed results with their 5D's sync speed.
Mihai – Here's my second guess, when you're using the Buff wireless gear and the 7D shoots at 1/320", then your Speedlite is at 1/1. Try dialing your Speedlite down to 1/32 and see if it still syncs at 1/320". I'm think that it won't.
Syl – that's a very interesting opinion, so I went and tested it (probably not the best test, but still).
I've put the 580EX on a lightstand, Manual mode, full power, and dialed the exposure until f/16 at ISO100 looked ok (although a bit overexposed, but that wasn't the goal of the test). Using these settings and no flash, frame was completely dark.
At 1/250, everything looked normal (as expected), with the frame being evenly lit by the flash. At 1/320" the frame was also evenly lit, but with what looked like a slight vignette on the bottom of the frame. I continued the test, dialing down the power of the flash to 1/2, 1/4 and increasing the aperture accordingly to f/11 and f/8.
Interesting thing is that by the time i got to f/8, the vignette shadow on the bottom of the frame was not there anymore.
I went down to 1/32 power and f/2.8, ISO100 and 1/320, but frame kept being evenly lit by the flash. Just for the heck of it, i went to 1/64, ISO 200 and f/2.8, but it still worked.
I will have to redo this test in the morning and post the pictures as proof (I was thinking of writing an article about the sync speed on my 7D for a while, but didn't get to do it yet).
Syl,
wanted to thank you for such great information – keep it up. I am a noob and on a tight budget and have been trying to determine whether I should get a Speedlite or a third-party flash. After reading your blog I see great benefits to keeping with the Speedlite. I primarily shoot landscapes but I am wanting to get into some basic portaitures (is that a word?) and know I will need a flash so think I will adjust my budget for the 430 EX II. I shoot with a Canon Rebel XSi so am assuming I can use the HSS functionality you talk about in your posts?
Thanks again!
Chris
Chris – Thanks for your kind words. As far as I know, the Rebel XSi (a.k.a 450D) is compatible with High-Speed Sync. I don't have a user manual for this model on hand, so you should check yours to confirm. A 430EX or 430EX II would be a perfect flash for you to start with. Absolutely worth saving for.
Syl,
Great info, I'm learning a ton, thanks! Just wondering if you always use the Canon Master/Slave system (not sure what it's called, I'm Nikon (CLS)). I currently have PW Plus ii's for triggers, and am looking to ugprade to a TTL version of PW or radiopopper just for HSS. Am I crazy for not using Nikon's CLS and spending a ton on these triggers? Thanks again!
-Josh
Josh – I always try to use the minimum gear possible. So, yes, I shoot Canon's wireless system whenever I can. If I need to move the Master off-camera so that the Slave can see it, then I use an extra-long E-TTL cord. If I'm shooting in a situation where a cord is cumbersome (like an event), then I will strap on the RadioPoppers. For this situation, as E-TTL radio triggers, they are second to none. I've tested the Mini/Flex system from PW and, with a respect due to PW for their leadership in the industry, I think the Mini/Flex is not as easy to use as the RadioPoppers.
My suggestion, use the built-in wireless on your Nikon gear until you have it dialed in. Then, I'd get a long I-TTL cord. Flash Zebra does not sell them. I've heard that another firm might be bringing them in this summer. If you shoot events and truly need I-TTL control of off-camera Speedlights, then I'd invest in a set of RadioPopper Px gear.
Hi Chris, the 430EX II will indeed do Hi-speed sync with the 450D/XSi. There's no limitations on either.
Hi Syl,
What about using ND filters to lower the shutterspeed to (or below) sync speed?
Then you can keep the shallow DOF (large aperture) and keep the flash's full power.
A dim enough ND filter or one of the vari-ND (Fader or Singh-Ray) would also to the trick right?
(if you don't have hi-speed sync for example when you only have the on cam flash for fill or 3rd party brands).
Regards Remko
Remko – I've carried a Singh-Ray Vari-ND for years. It's really great for situations where I don't have to look though the viewfinder… like when my camera is on a tripod and pointed at a moving body of water. As for the usefullness of an ND filter when shooting action, after about 3 stops of ND, I can't see through the lens. For me, HSS is a much easier way to shoot.
I've always wondered why more SLRs don't have an electronic shutter feature like many of the low-end Nikons do (such as the D50 and D40) that allow higher flash sync speeds. It's a lot cheaper and easier for beginners. There are certainly disadvantages of actually using the electronic shutter, but i wonder if it could be made optional on higher end gear.
Andrew – It's my understanding that it's largely an issue with the CMOS sensors used in most DSLRs… now don't ask me to explain the difference between a CMOS and a CCD. I'd have to go look that up (again).
Thanks for the series, you have answered quite a few questions for me.
Awesome, Syl… thanks a lot!
Hi Syl, Fair point about the darkness of the viewfinder with ND-filtering. I overlooked that part.
Keep up the good work. I'm looking forward to your book.
Remko
[...] Stil leven Mooie compo, maar DEZE techniek had wat kunnen bijbrengen. __________________ [...]
Syl Arena
Another superb, clear, and well thought out article. I'm frustrated I can not make your Washington DC workshop tomorrow, try to catch up with learning from you in NY or Boston. Good luck with your book, hope to be on the list when you publish.
Jim
Thanks for writing a clear example of high-speed sync. I've read lots about it but never completely understood it until reading your blog. The examples you provided and how you arrived at specific shutter speeds was clearly outlined. Great blog!
Great writeup Syl. I was thinking of another problem, with flash power being affected by aperture, at f/22, one probably can't get a speedlite to output enough light to illuminate the subject. Because the shutter speed affects ambient exposure and the aperture affects flash exposure. Wouldn't you need a pretty powerful strobe to expose the subject at f/22 and 1/200th?
Hi Syl,
I'm enjoying the post (got here from the MacNally blog, fwiw). Thanks for taking the time to do this.
Small pedantic correction: from f/22 to f/8 is three stops, not four. Likewise 1/800 to 1/6400. No effect on the result (because you made the error reciprocally), but thought you might want to correct before you go to print!
Best regards,
Patrick Snook
Hi,
Thanks for the informative articles. I'd like to point out that another issue with FAST shutter speeds, is the fact that you have to have the shutter open long enough for the flash to dump all it's energy. For example, the duration of a Nikon SB-800 at 1/2 power is 1/1100 sec. A shutter speed faster than this will not get the full dose of light. Of course, this is more of an issue with studio strobes.
Chuck
Syl,
I've been using Canon 550EX with Pocket Wizards and trying to get creative. It just seems that these strobes are not powerful enough…using an umbrella to maximize light softness, I have to get right on top of the subject. Any other lighting out there that is significantly more powerful than the Canon speedlights that is portable and doesn't require a second mortgage to buy? I've been asked to photograph a wedding (my first) and I'm starting to creep out and worry. I want portability yet enough light so I don't have to get too close to my subjects. I know David Zizer loves his Quantum strobe. What are your thoughts?
Thanks.
Chet in Rochester, NY
Chet – Not sure I understand… are you saying that you have to get the umbrella right on top of your subject in order to get soft light? If so, that is correct–it has to be in close to create soft light. The roll of an umbrella is to increase the apparent size of the light source so that the light comes at the subject from multiple angles. When the apparent size of the light source is significantly larger than the subject, the shadows are soft. THe shadows are soft because the light comes in from multiple angles. When the apparent size is small, as when an umbrella is pulled out, the apparent size shrinks as the quality of light gets harder. If this was not your question, ask again.
[...] “Flash limits the shutter speeds that I can use. A sync speed of 1/250″ is too slow.” High-speed sync (aka: Auto-FP sync if you’re a Nikonian) is a Speedlite-only mode that enables you to shoot at virtually any shutter speed. So, lighting your subject with a Speedlite means that you can use a fast shutter speed to freeze high-speed motion or to saturate the sky by underexposing the ambient. Contrary to the popular myths, you can’t do HSS with studio flash. Nor is a neutral density filter a good substitute. For more details on HSS, check out these articles: Simple Truths About HSS, Dimming The Sun – Part 1, and Part 2. [...]
[...] Dimming The Sun With High-Speed Sync: Part 2 [...]
Okay. So where do I go to figure out how to shoot -EV7 on a Canon 40D (just got my book today if it's already answered in there)
- Nancy
Nancy- Most DSLRs only have an Exposure Compensation range of +/- 2- or 3-stops. Beyond that, you have to set the camera manually. So, use an automatic mode like Av, to see what the camera thinks the exposure should be. Then switch the camera to Manual and set your exposure as you see fit — changing aperture, shutter, and/or ISO.
Dear Sil… I have one question and hope you can still answer me knowing this posted long time ago. Understand that to do HSS, all I need is a speedlite that can do HSS. Would the YongNuo YN-568EX work with my 450D? Is there a HSS function needed to be set in the camera? Thank you so much.
@William -
I can’t answer your questions about the YongNuo as I only use Canon Speedlites. The HSS function is set on the Speedlite menu — which on many Canon cameras can be assessed through the camera LCD.