Wetpixel Live: High Speed Sync

Underwater photography often has a cyclical turn over of techniques, with people rediscovering "old" techniques and creating innovative images with them. Thanks to recently released strobes and control circuitry, high speed sync (HSS) is now an option for underwater photographers. Wetpixel Live Regular contributor @Alex_Mustard and Wetpixel Editor Adam Hanlon are both excited about the creative potential that these new options offer and discuss how it works. 

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The Doug Perrine award winning photo of a bronze whaler you refer to in your talk is here:

https://wetpixel.com/articles/wildlife-photographer-of-the-year-doug-perrine

The housings are just referred to as "UK-German" housings, their make and model might be of interest if somebody can locate this info.

UK-Germany is a housing manufacturer. 

Their website is at http://www.uk-germany.com

Adam

Something that I should have done some time ago...

Test shots with:

Seacam Seaflash 60D

1/8000@f/16, ISO1600

1/4000@f/22, ISO1600

1/250@f/22, ISO100

Seacam Seaflash 160D

1/250@f/22, ISO100

1/8000@f/16, ISO1600

1/4000@f/22,ISO1600

Shot with Nikon D850, Nikkor 105mm f/2.8. Sync via wired S6 connection.

So excited for wide open images...shallow depth of field goodness

Adam, how would I go about figuring out which strobes offer HSS and how to set it up? I shoot with z330s now but having HSS flexibility would make it worth it to up grade for fast action. 

11 hours ago, Matt Imm said:

Adam, how would I go about figuring out which strobes offer HSS and how to set it up? I shoot with z330s now but having HSS flexibility would make it worth it to up grade for fast action. 

AFAIK, the only strobes currently on the market that offer HSS capability are:

• SeaCam SeaFlash 60D and 160D - strobes can be triggered by sync cords or fiber optics, but HSS is available only when using sync cords, only with Canon and Nikon cameras, and Canon/Nikon support is strobe model-specific - i.e. there's an SKU that works with Canon, and another SKU that works with Nikon. On the upside, HSS is available in TTL and manual modes.
• Retra Prime and Retra Pro - fiber optic triggering only, HSS is available only in manual mode, requires an LED trigger board in the housing to supply the proper triggering signal. UWTechnics and TRT Electronics have triggers compatible with Canon, Nikon, Sony, Panasonic and Olympus cameras (separate SKUs for each manufacturer as they have different flash communication protocls); UWTechnics triggers are shaped to fit a specific housing, whereas TRT triggers are generic boxes that fit most housings.

Hi Matt,

What @Barmaglot said!

Assuming a camera with a sync speed of 1/250 or so, I think HSS is not really a tool for fast action, but more one for limiting exposure for creative reasons. 

For example, shooting wide open with macro or water contact optics to minimize DOF

HSS will typically also limit a strobe's output, and this will create challenges for fast moving animals (which are often bigger)

Adam

6 hours ago, Barmaglot said:

AFAIK, the only strobes currently on the market that offer HSS capability are:

• SeaCam SeaFlash 60D and 160D - strobes can be triggered by sync cords or fiber optics, but HSS is available only when using sync cords, only with Canon and Nikon cameras, and Canon/Nikon support is strobe model-specific - i.e. there's an SKU that works with Canon, and another SKU that works with Nikon. On the upside, HSS is available in TTL and manual modes.
• Retra Prime and Retra Pro - fiber optic triggering only, HSS is available only in manual mode, requires an LED trigger board in the housing to supply the proper triggering signal. UWTechnics and TRT Electronics have triggers compatible with Canon, Nikon, Sony, Panasonic and Olympus cameras (separate SKUs for each manufacturer as they have different flash communication protocls); UWTechnics triggers are shaped to fit a specific housing, whereas TRT triggers are generic boxes that fit most housings.

There just one model of the Seaflash 160D and it does both N or C unlike previous Seacam D flashes - I know as I have both N and C versions of the 150D. Apparently the strobe is "smart" enough to be able to detect which brand of camera it is attached to. One hint may be due to N using 5 wires whereas C uses 6.

1 hour ago, adamhanlon said:

Hi Matt,

What @Barmaglot said!

Assuming a camera with a sync speed of 1/250 or so, I think HSS is not really a tool for fast action, but more one for limiting exposure for creative reasons. 

For example, shooting wide open with macro or water contact optics to minimize DOF

HSS will typically also limit a strobe's output, and this will create challenges for fast moving animals (which are often bigger)

Adam

Could you be more specific about how much output is reduced. Also the number of flashes per charge. If one is using an ISO value in the thousands (which I regularly do) and HSS at 1/64 (or the lowest setting on the 160D) what kind of frame rate is possible and how many shots on a battery charge? For now just one flash. I would expect that ambient light would do most of the exposure. The strobe is simply to fill in a bit of the shadow which might include the whitish bottom half of a shark (so reflective).

Hi Tom,

I haven't done any testing, but given that the strobe is firing multiple times per frame, this limits its output. It doesn't have time to recycle.

My guess is that as always, frame rates will be slower than the camera's...and slower than a "norma" shutter speed using the same underwater strobe at a comparative setting. 

Unless you are shooting wide open (which would probably limit which parts of the shark are in focus) I don't see a need for HSS in this application? Even makos are sharp at 1/250...

Adam

4 hours ago, Tom_Kline said:

There just one model of the Seaflash 160D and it does both N or C unlike previous Seacam D flashes - I know as I have both N and C versions of the 150D. Apparently the strobe is "smart" enough to be able to detect which brand of camera it is attached to. One hint may be due to N using 5 wires whereas C uses 6.

There is a setting on the 160D to switch between Nikon and Canon rather than the strobe detecting which is needed. I believe N also uses 6 wires.

31 minutes ago, ScubaLute said:

There is a setting on the 160D to switch between Nikon and Canon rather than the strobe detecting which is needed. I believe N also uses 6 wires.

I read this in the instructions: "When switching ON the unit you first see a 3 part battery symbol indicating the battery capacity status and the flash type followed by the NIKON or CANON identification." which I took to mean the strobe knew the details (identification) of the camera when it is powered up. Maybe they need better clarity.

Nikon has 5 contacts in the hotshoe and so has 5 wires. Hence the Nikonos-derived  N5 bulkhead designation.

3 hours ago, adamhanlon said:

Hi Tom,

I haven't done any testing, but given that the strobe is firing multiple times per frame, this limits its output. It doesn't have time to recycle.

My guess is that as always, frame rates will be slower than the camera's...and slower than a "norma" shutter speed using the same underwater strobe at a comparative setting. 

Unless you are shooting wide open (which would probably limit which parts of the shark are in focus) I don't see a need for HSS in this application? Even makos are sharp at 1/250...

Adam

 

 

It must recycle at some point. Are you saying the strobe is dead after an HSS shot?

As for blurring. I got a blurred salmon a few days ago when shooting at 1/500th - an ambient light shot

Tom,

You are querying HSS strobe output. My point is that in HSS mode, the strobe fires multiple times in each frame, and this limits its power. The capacitor cannot recharge quickly enough for full power dumps. 

Of course, there are many reasons for blurred shots, and shutter speed in one of them. Your example to which I replied was talking about sharks: 

Quote

 fill in a bit of the shadow which might include the whitish bottom half of a shark

I shoot Nikon with S6 connections, so do not believe that the 160D auto senses whether it is attached to a Nikon or Canon camera via the number of connected wires. There is a setting in the menu that allows the user to switch between the two camera brands. 

13 hours ago, adamhanlon said:

Tom,

You are querying HSS strobe output. My point is that in HSS mode, the strobe fires multiple times in each frame, and this limits its power. The capacitor cannot recharge quickly enough for full power dumps. 

Of course, there are many reasons for blurred shots, and shutter speed in one of them. Your example to which I replied was talking about sharks: 

I shoot Nikon with S6 connections, so do not believe that the 160D auto senses whether it is attached to a Nikon or Canon camera via the number of connected wires. There is a setting in the menu that allows the user to switch between the two camera brands. 

I am not asking about a full power dump but, e.g.  1/64, see above query from me. For example in your above pix done with the 160D you indicate that the pix were shot at f/22 or f/16. Using these small apertures may have required a higher manual power setting. Recycling (i.e. recharging the capacitor(s)) may have taken you a few seconds - you do not say. What if you had shot at f/2.8 instead? Would the recycling time have sped up say to less than one second - this would be useful to know. If the the recycling time is fixed regardless of power used then HSS may not be all that useful, IMHO. Maybe the Retras are better???? BTW I have not used HSS with my Canon version 60D but I am not expecting much with four AA batteries inside. As well I am more likely to use HSS with an RS lens (therefore N rather than C) as they seem to do much better at larger apertures.

I was shooting salmon by remote control which also uses an S6 connector however only 3 wires are actually used. I know this for a fact because I installed the S6 bulkhead on the housing myself and know the 3 extra wires are dangling disconnected inside the housing. Nikon has used 5 wires since TTL flash started - I have no idea (other than possible use for the slave strobe when hooked up with a special circuit they make - see box on p.24 on the manual and other D model strobe instructions) what Seacam does with the "spare" wire of the S6. I was guessing that they could use this fact as a way of detecting brand. The instructions would be far more useful if they mentioned in the line I quoted that this is a user adjustable parameter with a page reference so that if the wrong brand is displayed one would know what to do. Also what the blazes is meant by flash type (also in the quoted line)? Maybe they mean flash mode such as TTL. Again a page reference to see where is can be changed would be very useful here.

Tom,

I think we are at cross purposes here.

In HSS, the strobe fires multiple times per frame or shutter actuation, rather than a single flash as per normal (when used in manual mode).

As it is firing multiple times per frame, it needs to recycle while the shutter is still open (which given the fact that we are talking fast shutter speeds, is very fast indeed). 

This is why it cannot be used at high power. For what it is worth, this is a feature of HSS and is unlikely to be better (or worse) in different strobe brands.

Recycle time between shutter actuations seems to be similar to normal, although I have not deliberately tried to time it. Battery packs are more efficient then AAs due to reduced inter cell resistance, but the Retra Supercharger may increase recycle speed over the 160D. This needs testing though.

I know how HSS works but am rather skeptical that the strobe recycles between individual flashes within a shot, more like a small amount of the charge is depleted for each flash and the capacitor gets refilled after the frame. We are talking about tens (maybe not even tens) of micro seconds per flash. 1/1000 is one millisecond or 1000 microseconds so 1/8000 is a bit more than 100 microseconds so 10 flashes of 10ms each would just about fit. Alex mentioned in his video (months ago) that the flash tubes used in the new Retras enable this teeny weeny flashing, but I am clueless about the Seacam 160D (it is also not a full circular tube like the Retras).

Is there any power control (strobe output) in HSS mode? E.g., is it set by the shutter speed alone.

Again, I think we are talking two sides of the same coin.  Perhaps watch our video above, Alex explains how HSS works succinctly...and points out its power shortcomings.

"a small amount of the charge is depleted for each flash" which must deplete the capacitor and means that full power flash is hence not available....Typically HSS uses 3-4 strobing flash cycles per frame. So assuming 4, and the capacitor depletes fully during the frame, each flash can be no more than 1/4 power. If the capacitor could recycle between flashes, this could be increased, but as you point out, the interval between flashes is so short that it cannot do so. Hence recycle time limits the power output in HSS.

The 160D and 60D allow HSS via this technique too. The images above are captured using it...The shape of the flash tube is not relevant, the key ingredient here with both the Retra and Seacam strobes is their electronics.

Adam

The Seacam 160D can synch at 1/8000 (p.7 of the manual). This is enabled by the shutter becoming a narrow slit. I am skeptical that 3-4 flashes will do it.

7 hours ago, Tom_Kline said:

Nikon has used 5 wires since TTL flash started - I have no idea (other than possible use for the slave strobe when hooked up with a special circuit they make - see box on p.24 on the manual and other D model strobe instructions) what Seacam does with the "spare" wire of the S6.

I have used a pair of 250D strobes for 14 years and have the circuit mentioned in that box on p.24 in my housings, which use S6. I think the extra wire allows the left strobe to communicate to the right strobe. When I leave the right strobe on TTL it fires at whatever manual setting I set on the left strobe, not TTL. It is very handy to be able to manually change the power on both strobes with one switch. My guess is the extra wiring allows the left strobe to become the master of the right strobe.

BTW, should you get one of the new 160D strobes it will arrive set for Nikon (as factory default). You have to change the setting to switch it to Canon. I know someone who is a Canon shooter and got his new strobe, set to Nikon, and thought the order was a mistake because he didn't read the manual through to learn about the ability to switch. I watched a very nice video from last year's DEMA on this site with Harald Hordosch describing all of the features of the 160D, which is where I learned about the feature. I admit I'm also not a manual reader.

I am anxious to get my pair of 160Ds wet. They are an excellent product.