Seacam Sea Flash 150 Digital Review


The Seacam Seaflash 150 is every bit a Seacam product.  It’s exquisitely built and very handsome to look at.  Housed in hardened anodized aluminum, all the controls are at the back of the strobe.  There are 2 plastic dials controlling modes and power levels.  A large cap covers the battery compartment.  It comes with a plastic macro protection ring, power supply, S6 -TTL cable and manual in printed and CD version. A diffuser is available as well as different accessories.

The ON/Mode dial has OFF-ON-P1-P2-SL-SOS settings. P1 and P2 are the power settings for the LED light.  SL is Slave mode and SOS is just a mode where the strobe blinks SOS in morse code.

The TTL/MAN dial has TTL and manual modes with 1/1, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64 power steps. In the manual, there are another 5 half steps of power in between those.


The ON/Mode dial is exactly 2cm apart from the TTL dial when the Mode dial is in Off position and the TTL dial is in TTL position.  If those with thicker fingers (either naturally or with thick gloves, there are accessory large dials which plug right onto the existing dials.

The LED window displays battery power %, flash energy delivered and which mode the strobe is in. The nice thing about this strobe is that in ETTL mode, it will actually display the level of energy of the last discharge for 8 seconds.

The ball joint that screws into the bottom has the same silver finish and uses a hex key to tighten, the same sized hex key used on a few of the screws on Seacam housings.  How convenient! Of course, the S6 plug is also at the back, with a black finish cap matching the esthetics of the black on silver design.

The battery compartment cover has a single o-ring and the battery pack has a folding metal bail handle to pull the battery from the battery compartment.  The battery itself, is a 1.85AH/7.2V NiMH packed into a proprietary cylinder pack.  It weighs 260g and is a very elegant solution. 

The charger has dual round pin (euro) plug with approximate 1m cable, linked to a single point female plug.  It takes only 100 minutes to fully charge the battery pack.

The Flash Arms system are hollowed aluminum arms, finished in the silver motif as with all Seacam products.  The t-bar ball joints are also similarly finished. The clamps are fiberglass with a lever arm.

From the silver finish to the neoprene covers that are available for every part of the strobe assembly, this Seacam product reflects the high quality I’ve come to expect from Seacam.

There are 2 models, the 150D and 150O. The 150D can be ordered for Nikon iTTL or Canon ETTL (specified when ordering, the strobe can only work with ETTL or iTTL but not both TTL protocols). For TTL in both brands, a S6 sync port is needed. The 150O or Offshore is a 200m depth rated version.  The way to tell the difference is when you turn on the strobe, the LED will display a dot to show it’s a Canon strobe.

With the Sea Flash 150, the ETTL circuitry doesn’t show up as a strobe to the camera (Canon cameras can control certain aspects of the strobe on camera).  When using the camera menu options for external flash, it shows as no strobe attached, but you can change metering mode, Flash Exposure Compensation (FEC) and enable/disable flash firing. All other menu options are grayed out.  2nd curtain flash is set by putting the strobes into SL (Slave) mode.

Another feature I thought was be cool was having the 150 off camera in Slave mode. The slave sensor is sensitive enough that it would fire even with the strobe about 3m away, so long as there is line of sight. There isn’t TTL in slave mode, which is a pity as metering would nice to create nicer lighting options than just the 12 power levels.

Seacam also designed a feature that is unique as far as I know in the underwater strobe market: the LED display of power levels discharged. To test this I just pointed at a subject and scrolled through FEC in 1/3 stops. Each time it fires, power levels popped up.  78, 62, 52, 42 and so on, each corresponding to 1/3 stop.  I was pretty impressed by that and appreciated that sort of control especially in macro.


Using the strobe in manual mode is very simple.  There are 7 marked levels as shown in the pic.  Between the marked levels is a click which is ½ a stop.  Essentially there are 12 power steps which Seacam calls 7+5 steps: 98%, 74%, 50%, 38%, 24%, 18%, 12%, 10%, 8%, 6%, 4% and 2%, which correspond to 1 stop per level plus five half stops. It’s a matter of choosing the power level and shoot. 

A minor gripe is that it’s not very clear the ½ steps are there. In the user manual, there is mention of a “sensitive step” level between the 7 power levels, however, it doesn’t say how to access it other than what is in the manual:


12 different output energy steps can be selected (7+5). A sensitive stop is also possible between the 7 fixed positions.

The description is neither clear that it is ½ stops, nor are there any markings on the controls to indicate they exist.  I actually forgot that I tried the in between settings because it was a click to see if they fired.  Only after being reminded by Harald and looking at the images did I remember I tested it. Simple markings and clearer indications in the manual would’ve clarified everything.  It is a very minor gripe.

The beam from the Seaflash 150 is very nice and wide.  At 130°, it’s probably the widest strobe around without using a diffuser.  The rating says the strobe pumps out at 14GN underwater at 1m.  At 4400°k, it’s tuned towards making water extra blue, due to the warmer tones of the white balance at that color temperature on the subject, with the water in the background.  But enough with numbers, how does it perform?


There’s not much to say about this strobe.  Simply put in a charged battery, ensure the S6 cables are inserted correctly and tightened. Then choose the type of beam for the occasion, diffuser, normal or macro rim. Then it’s ready to go!

BUT with ETTL, there’s another dimension to consider setting up, and that’s metering.  The Prelude 60D housing didn’t allow access to the menu options in the housing, so it’s important to preset this.  the most important aspect of metering is choosing the right metering mode for the situation. I first tried the strobes in South Africa during the Ocean Safari. As I mentioned in the Seacam Prelude 60D review, I had a bit of an issue with the strobes. I’d not used ETTL mode in such action before. Fast pace action that demanded quick recycle time, good metering and ETTL I thought would be very helpful in getting the shot.  I didn’t have time to experiment with settings for the strobes and just trusted that I could make it work. I was very wrong!

The Botched Field Test : It’s All About Me..tering

Since Stephen Frinks has already tested the SeaFlash to show that ETTL metering does work in terms of controlling flash output, I thought I’d concentrate on how to understand the settings and the effects of each metering mode.

As mentioned earlier, I made several mistakes in setting up the strobes for ETTL.  Instead of trusting Canon’s ETTL II metering system, I stuck with what I knew from using Canon ETTL topside.  I’d always found the ETTL metering was better looking with Average metering rather than Evaluative. I stuck with what I knew.

The idea was that the ETTL metering will use the SeaFlash as fill light and I’d expose to shoot -2/3 to 1 stop from natural light.  The problem with baitballs, there are several different factors to consider: the shiny baitfish, the almost all white gannets, the grey dolphins and bronze sharks and of course the sun.  Average metering bunches it all together and just underexposes the shot if there’s a main light source like the sun or shiny fish.  ETTL also meters to 18% grey when using Flash Exposure Lock (no access with the Prelude 60D housing), so while it should work very well with dolphins and sharks, shiny fish throws it off and it underexposes.

The Sea Flash beeps when it fires at 100% power to warn the user that it can’t go higher than that.  When it doesn’t beep, that is a good reminder to check exposure of what powerful it fired at so one can know how to set FEC for proper exposure. For those using the Prelude 60D housing, setting Image Review to 20 seconds will allow the user to check exposure as a workaround.

Another issue with baitballs and my shooting style was that I shot in high fps mode. The 60D can do 5.3fps for up to 16 frames. The recycle time for a full dump with the SeaFlash is 2 seconds. The conditions, shooting in ETTL (which requires a preflash) and the high frame rate of the 60D just overwhelmed Seaflash, which could not keep up because ETTL was making it fire consistently at 1/2 power or higher. It wasn’t powerful enough for how I was shooting. This is mostly my fault as I’m accustomed to my own 250W strobes which can fire at 8fps at 1/4-1/2 power. I did not adjust my shooting style to the equipment and thus it was a bad test on my part.