Sunday, November 23, 2014

HSS with the Cheetahlight CL-360 and Yongnuo YN622Ns

Several people have asked about High Speed Sync (also known as FP for Nikons).  High Speed Sync allows you to set a sync speed (and shutter speed) above your camera's regular maximum sync speed (which usually ranges somewhere between 1/60th sec to 1/250th sec depending on camera model).

The reasons for wanting to set a high sync speed aren't as intuitive as you would think.  Some people think they need a high speed sync to freeze action.  That usually isn't the case.  That is because the short duration of the flash (ranging from 1/1000 to1/10,000 sec) is usually sufficient to freeze action, at least where the flash is the main source of light.

So why would you need a high sync speed?  There are several 'use cases', but probably the most common is the desire to open up your aperture for shallow depth of field when using your flash outdoors during the day.  In those cases, in order to get to f4 or to say an f2.8, you usually have to set your shutter speed well above 1/250th of a second.

You have two choices in that case, use HSS to allow your sync and shutter speed to go above 1/250th sec, OR you could instead use a neutral density filter to bring down the ambient light so your shutter speed will be at your sync speed limit or less.  The issues with using neutral density filters are that it decreases the light your camera gets for focusing, and if using a really powerful neutral density filter, you can introduce a color cast into the image (as most are not 100% neutral).  So instead of carrying around neutral density filters, you can also use HSS to get your shutter speed up so you can use the aperture that you want.

One other use case, is if you are freezing action AND want to mix flash with ambient light.  When doing that, even though the flash freezes the action for the part of the exposure done by the flash, a long shutter speed with the ambient light could introduce some ghosting.  In those cases, you might want to use HSS to get your shutter speed up for freezing the ambient light action.

In this video, I show how to set up HSS on the Cheetahlight CL-360, the Cheetahstand CL-TX Trigger (used for remote power control of the CL-360) and my Yongnuo YN622Ns:

There are several possible set ups, some that work better than the others, and I walk through those in this video.  The CL-TX Trigger (also known as the ft16) does not directly support HSS (most of the image gets darkened by the shutter creeping into the exposure as seen in the image below),

so although you can still use that trigger to remotely control power, a different triggering system needs to be used to support HSS.  That is where the Yongnuo YN622N system (including the YN622N-TX) comes into play.

The YN-622N can recognize when your camera is set to FP mode, and automatically controls the HSS communication to the Flashes it controls.  In this case, the CL-360 has to manually be placed in HSS mode, but once that is done, it understands the communiction coming from the camera and the YN622N to properly control the flash so that you don't see the shutter mechanism in the image.

The CL-360 can also simulate HSS support in its normal mode at full power (1:1).  In this mode, the flash duration is long enough that it stays illuminated for the entire travel of the shutter so you get a properly exposed frame.  The interesting thing is, this method gives just a little more power for your exposure than using the HSS mode in full power.  I show that in the video, but also in the images below:

All three of the images below are shot at 1/8000 of a second and the CL-360 set at full power (1:1).  The first one is shot at f5.6 with the CL-360 set to 'on' on the flash.  The second one has HSS turned 'off' and is still at f5.6.  The third is with HSS  turned 'off with the aperture set to f6.3.

1) Shutter Speed 1/8000; Aperture f5.6; HSS set to 'on'

2) Shutter Speed 1/8000; Aperture f5.6; HSS set to 'off'

3) Shutter Speed 1/8000; Aperture f6.3; HSS set to 'off'

If you have any questions or comments, please post those in the comments section and I will try to respond.  Try HSS with your system and let me know how it works out.  In the meantime, Happy Shooting!


David said...

Would you ever see a benefit to this setup in architecture photography, ...I'm thinking more along the lines of ensuring accurate representation of the outside skies when conducting internal photos.
Reason I ask is I have D600.....4 x 622Ns plus a TX and Godox AD360 flash.

David Carrico said...

@ David, That could be a benefit, but I imagine that if you are photographing inside, if you want everything in the interior in focus anyway, you could balance it by decreasing the size of your aperture instead of taking shutter above your sync speed. However, if you still want a wide aperture, then yes, HSS is definitely a tool you can use....

Michael Jurick said...

Hi David,

Thank you so much for explaining this in great detail. I also watched your youtube video so I understand this setup perfectly. I wanted to ask one critical question for me.

I would like to use this setup for portraits so I can use 1.4 aperture for portrait work outdoors in mid-morning sunlight photographing fast moving kids. What I'd like to do is NOT have to use full power on the 360 if I don't need it. Let's say I wanted to use the LONG duration flash (HSS set to OFF - b/c the overheat sensor comes on in HSS mode after only 20 pops and then renders the photoshoot useless b/c of the painfully long recycle time). Let's say I wanted to use 800 of a second or 1000 of a second (not the full 8000/sec) and 1.4. Could I use the system you describe with 1/4 power on the 360 so I can recycle faster AND not trigger the overheat protection on the light? Thanks so much in advance for you answer!

David Carrico said...

@Michael Jurick,
Unfortunately you'll get the shutter in the frame if you are trying the long duration method at less than full power, so that won't work. I haven't tested myself, but I think the overhead 20 shot limit is only going to kick in if you are in HSS mode AND full power, so if you are in HSS and 1/8 power for instance, I think you will be a lot more shots (again, I haven't actually tested that myself). If 1/8 or 1/4 power does not give you enough light, you can add light sources to make up for it. So for instance, in addition to my 360 (I only have one), I have several Nikon flashes, and I could add one or two of those to the mix (since light is additive) to make up for not having the 360 at full power. Sorry I don't know of a better solution. Let me know what setup you end up on though, as I am interested to hear how it works for you. Thx.

Michael Jurick said...

Thank you so much for the quick reply. Sad to hear long duration only works in full power mode.

I have tested the light in HSS mode at 1/8 and 1/4 power and the overheat sensor kicks in at about 20 pops - super lame as I really would love to be able to use these outdoors with wide aperture for a family/kids portrait session in mid-morning sunlight without limitations.

Thanks again for your insights and review and I'll will keep checking out your blog.


David Carrico said...

@Michael Jurick,
Wow, that surprises me the overheat protection still kicks in so quickly at less than full power in HSS. Thanks for the info.

Regarding your challenge, the other option you could test is to use neutral density filters to bring the shutter speed into the flash sync speed range. If you were going to shoot at 1/1000 second anyway, you would just need a 2 stop filter to get you into sync speed range of 1/250 sec. Kids would probably still be ok at that shutter speed, and even though they would get ambient exposure (and so the shutter speed would impact the motion), the short duration of the flash would help to freeze them. Good luck!

Wayne Brown said...

Hi Dave what is the model number of the PC sync cable you used on the Cheetahlight CL-360 or can you tell me where i can purchase one.


David Carrico said...

@Wayne Brown. They are basic PC sync cables. I generally like the FotoTech ones and the ones from Cheetahlight, but any will work.

Sweet Emotion Boudoir Photography said...

Hi David,
I have the same triggers that you use but on the Canon side. I was wondering what the settings were in the 622n-TX, did you have to change them to work with your AD360? I have the TX on camera and then the 622c with the AD360 and it's still not doing anything. I noticed that you still had the USB Trigger attached when it worked. If you took that out does the HSS still work. Just trying to figure out how to make mine work. Thanks.