ReyeR
Guest
I'm re-arranging your post to explain better:
I mentioned this specifically in context to flash exposure compensation - don't confuse this with the general S-TTL concept of the D-2000.
The EV dial on the S-2000, in S-TTL mode, behaves like a 'flash exposure compensation' dial. The D-2000 is still 'mimicking' (see above) the master TTL strobe, but you can get the D-2000 to stay on longer (than the master TTL strobe's duration) by dialing this dial to the '+' side, therefore allowing you to compensate for a subject that might fool your camera's TTL flash exposure measurement e.g. a dark subject on a light background. Dial the EV controller to the '-' side and it'll cut off BEFORE the master TTL strobe cuts off. Getting the D-2000 to stay on longer or a '+' compensation is easy understand, it just detects when the master strobe has gone off (trailing edge event) and continues to stay on longer for the amount dialed in. But how the D-2000 know when to cut-off before the master strobe quenches is what I don't understand. This is what I was referring to with my statement. The D-2000 can detect the trailing edge event but it has no idea when this is going to happen so it can't really pre-empt this and cut-off before this event by the amount dialed in.
Yes, it has a similar concept to the Weikamp TTL adapter. When I used the term 'mimick' TTL I meant exactly that: the 'mimick' circuit watches when the master TTL strobe fires (leading edge event) and fires the D-2000; it continues to 'watch' the master strobe; when it detects a quench (trailing edge event) it'll quench the D-2000. It is simply copying what the master TTL strobe is doing.Yes, they are in sync with the leading edge (beginning) of the firing internal strobe, but what about the trailing edge (end) when the strobe is on its way down? The trailing edge is what tells the external strobe when to stop! Are you saying that Inon has a built in Heinrich TTL adapter? Because there still isnt a feedback path for the "quench" signal.
Nope, in S-TTL mode it does not require the user to preset the aperture settings. I hope you're not getting confused because the EV dial is shared with three different modes. The f-stop numbers are for the External Auto mode. The EV controller acts like a flash exposure compensation dial (see below).What is really happening is that Inon is guessing on what the flash duration (equates to strength of light) should be at a given distance, aperture setting, and film speed, ISO.
That is why Inon needs to have the user preset the aperture settings on the strobe to match the aperture on the camera. The preset setting on the strobe are the actually strobe duration times for a set aperture opening in order to get a decent exposure... then increase or decrease the strobe power to bracket the shots. Which is just like shooting in MANUAL! Only in Inons case the strobe power is varied and not the aperture, as the case in manual shooting.
Ok, lets say that Inon really meant "Syncro" meaning in Sync or in Step. Meaning that Inon is tapping off the internal flashhead, the true TTL system of the camera. You had mention this yourself:
"How the D-2000, as a mimic TTL strobe, knows when to cut-off before the master TTL strobe quenches is beyond me, but apparently it works)."
I mentioned this specifically in context to flash exposure compensation - don't confuse this with the general S-TTL concept of the D-2000.
The EV dial on the S-2000, in S-TTL mode, behaves like a 'flash exposure compensation' dial. The D-2000 is still 'mimicking' (see above) the master TTL strobe, but you can get the D-2000 to stay on longer (than the master TTL strobe's duration) by dialing this dial to the '+' side, therefore allowing you to compensate for a subject that might fool your camera's TTL flash exposure measurement e.g. a dark subject on a light background. Dial the EV controller to the '-' side and it'll cut off BEFORE the master TTL strobe cuts off. Getting the D-2000 to stay on longer or a '+' compensation is easy understand, it just detects when the master strobe has gone off (trailing edge event) and continues to stay on longer for the amount dialed in. But how the D-2000 know when to cut-off before the master strobe quenches is what I don't understand. This is what I was referring to with my statement. The D-2000 can detect the trailing edge event but it has no idea when this is going to happen so it can't really pre-empt this and cut-off before this event by the amount dialed in.
It isn't totally useless, it'll work for some situations. And again, you can 'compensate' by dialing in a different aperture number than on your camera and influence it to give more or less light when the sensor gets fooled.The external Auto mode is not much use, unless the strobe is mounted right next to the cameras lens, which for most UW folks here is a no-no. This is because the sensor is mounted in the face of the strobe itself. As the strobe fires, the light reflecting off of the subject has to come back to the strobe face in order to shutoff the flash. The problem here is that the strobe is usually mounted away from the camera, so the camera may see a different light than what the strobes sees.
I haven't heard of this so not sure what you are talking about.Ikelite has a similar setup but their sensor can be mounted remote, like near the camera lens.