After all the recent talk here about Optical Slave & Delay settings I was really pleased recently to put it all together and get things working in practice. One of the main uses for the Cactus RF60 I had in mind was for use in HSS situations, in combination with my two Pentax AF-540FGZ (I & II) flashes.
Of course we all know that one of the big issues for Pentax users of HSS wireless flash is that it ties up one P-TTL HS capable flash on the camera to serve as the essential trigger. So I only had one other flash as a slave, and sometimes I'm looking for more power, or just for some more sophisticated lighting arrangement during HSS. I really didn't need more than two system dedicated flashes, and so in the interests of economy I bought the RF60 .... and combined it with a V6 transceiver for the added convenience of its remote power and zoom control.
So this is a 'mixed mode' flash configuration .... the Pentax Dedicated flashes must operate in P-TTL mode when in High Speed Sync, and of course the Cactus is a manual mode flash. Here is how the 3 flashes were used ....
1) The Cactus RF60 was placed on a lightstand and used as a 'Main' light facing the subject from the front. This flash had a Gary Fong Powersnoot attached to channel and focus the light narrowly and 'replace' lost power through the very short exposure times I'd be using ......
2) The Pentax AF-540FGZ was placed in a softbox off to the subjects left to act as a fill-in and to control the shadows created by the frontal main light .....
And now you can see my willing subject
The only one around that morning who had nothing better to do
3) The camera (Pentax K7 with SMC F35-70mm) had the AF-540FGZII mounted on top of the V6 .... the Pentax Flash was set to Wireless HS 'Control' mode, acting as a controlling trigger only (no contributing lighting), and a Gary Fong Lightsphere was attached with the flash head pointing straight up .... (a little like this shot .... ) The only difference from this image is that I also had the V6 on the camera (under the flash) as I was using it to control the RF60s power and zoom.
As the shooting position was in between the two flashes I needed to get the triggering light into the optical sensors of both slave flashes, which were 180deg opposite each other. The Lightsphere sent the signal in all directions and so I was able to trigger both flashes with no issues.
Here is the position of the Main light in relation to the subject ....
And these two show the relative positions of the two flashes ... the shooting position was in the middle of them ....
The purpose of the HSS technique was to balance and control the high contrast in the scene. There was bright sunshine from the left (behind the subject) which added a nice free rim-light
, but the Teddy's front and face were in shadow (he'd have been squinting terribly if I'd faced him into the sun) .... if I'd exposed for the shadow on his front then my background would have been overexposed, the sky massively. I needed to keep a fairly wide aperture because of the busy distracting background ... and, well, this is a portrait after all (and we're supposed to set wide apertures for portraits, right ?!
)
So I settled on around F4.5-5.6, and an ISO of 200 for good quality. When I pointed the camera at the background and metered to get a good exposure there, the time value was around 1/500th sec. I also wanted to tone down the background as well to emphasise the subject, so I dialed the time value even shorter to between 1/800th - 1/1600th sec (the light kept changing a bit) ..... I kept it at around 1.3 - 2.0 stops below the meter-centre.
This was the result of this 'ambient' exposure without the flashes firing .....
So clearly it was time to fire up the flashes .... The Cactus RF60 was set to HSS Sympathy mode, and Optical Slave mode 2 (OS2) to fire on the Main Flash. However as we've been discussing on the recent thread about this, when a P-TTL control flash is used there is an additional wireless instruction pre-flash, which the RF60 is triggered by, and so I needed to set a delay of 15ms also.
The Pentax Flash operated in wireless P-TTL mode, as a single slave as far as the P-TTL system was concerned. The P-TTL metering system would not take account of the RF60 manual flash at all, because the RF60 does not fire until the actual exposure, and so the camera does not see its effect during the pre-flash. In effect there are two side-by-side but completely independent flash exposures. I needed to test and fine tune each one in isolation before combining them. The RF60 power was controlled from the V6 on camera, and the Pentax flash was controlled by Flash Compensation on the camera also, so I never had to move to the flashes to adjust their outputs.
Here is one shot using just the main RF60 light, showing its shadow effect ....
And here's a couple showing the full result with the fill-in flash from the softbox with the underexposed background as well ....
I was a happy HSS Flashing Bunny after that testing session. To get everything synced and be using two off-camera flashes (one manual and one P-TTL) was exactly what I'd been wanting to achieve, and I am sure will lead to better quality lighting effects for HSS work. Both the Pentax P-TTL wireless system and the Cactus Manual one proved their worth and made a great HSS partnership !
Now, next I just have to persuade a far better looking model to stand around in the sun for me ....