Rx100 ys01 ttl

[Interceptor121]

No. The systems is exactly the same. If the preflash gets no return you get a full dump. Fiber optics are multimodal and travel fast wired cables are connected to a terminal that only does one thing. The optical connection is always superior for any transmission you do to copper or any wire. What changes is the quality of the P-TTL of the camera and the ability of the strobe to emulate the internal flash. As I have tested the YS-01 and the inon Z240 with the RX100 I can tell you the two strobes behave differently. The inon sends a much stronger preflash signal when I connected the two strobes the YS-01 would barely fire as a consequEnce. Connecting a single strobe results in perfect exposures with the inon and many overexposed pictures with the Ys01 in virtue of the lack of controls. I had plenty of overexposed pictures with the panasonic LX7 with the YS 01 in macro too. When you are really close you end up in a situation that even little is too much, the inon strobes have a ttl low setting the sea and sea don't so you need to play with the dimmer. At some point you might as well shoot manual

 

[bvanant]

That is interesting. I have not a RX100 but in my hands on Canon 7D, the Inon and S&Ss behave pretty much identically. I have not really tried to figure this out with the EM-1 but maybe I can look at that this weekend (no diving, too much wind).
Bill

 

[Interceptor121]

The same YS-01 worked fine with my canon s95 indeed

 

[alta5]

some great info in here. After some more reading and testing this is what Im observing.
Aperture changes the ttl flash power. is this normal? I guess the short answer should be yes, but it should keep the exposure relatively the same. However, I'm getting scenes that are inversely exposed in correlation to the aperture.

lets say I set iso 100, shutter 250 and shoot at f1.8.
aperture wide open, rx100 ttl sensor gets more light and signals a small flash. scene sometimes underexposed.

at f5.6 the aperture is somewhat open, camera issues medium flash to strobe and scene generally evenly exposed.

at around f8-11, aperture is small, little light, camera issues large flash or full dump. scene generally overexposed.

so from what I understand the strobe pre-flashes at subject and cameras ttl determines how much flash is needed. camera takes the entire frame and tries to average 18% grey. Depending on color of subject and background as well as reflectivity of light from pre-flash, the cameras ttl will determine flash power needed.

Shutter speed can change the ambient light, generally the background and should not affect the light from the flash (aperture and iso obviously also contribute to ambient light.) Now from what I understand aperture and iso are not supposed to affect ttl exposure because the camea ttl compensates the flash so that f1.8 or f11 should have the same exposure on the subject. In my tests I'm observing the flash compensate but it's overcompensating. Now this could be due to a few reasons:
1) specific to gear
2) specific to land conditions shooting where ev less than -2 at iso 100
3) the strobe is set to perform differently under water...although underexposing flash at f1.8 seems confusing because I wouod think the distance light travels would be less underwater.

---------- Post added April 25th, 2014 at 08:19 PM ----------

I was also wondering: if the cameras ttl needs to read the light reflected by the strobe pre-flashing; how do you get a correct ttl exposure if you dont aim the strobe directly at subject due to backscatter? also does a diopter affect ttl sensor picking up light either positively or negatively?

 

[Interceptor121]

TTL reacts to the aperture and ISO and depending on the type of metering will read differently. Am not sure if when you use the flash the camera defaults to centred average but it's probably true so ambient light is somewhat irrelevant. Ttl only works of lights get reflected back in the lens. If you aim the strobes in a way that there is no reflection ttl fails and you get a full dump. If you aim your strobe properly and the strobe preflash is strong you can use ttl for all macro and most of cfwa. The backscatter discussion is a separate one as you could aim the strobe directly as long as it is far from the axis of the lens