Strobes for MXIIEX

[scorpiofish]

Here is where I read about TTL synch of YS-90.

http://www.ikelite.com/web_pages/compare_ys60.html

Fact of fiction, I do not know.

 

[DiverX]

When I was using the MMII-EX I had a YS60 & a YS90duo. The YS90duo worked everytime in slave mode on TTL so not sure what Ike means.....*shrug*

 

[Dee]

According to those who use them, Ikelite makes a good strobe.

I'll admit, I don't own a YS90 yet but I have done alot of research and have several friends who do own it and they've had no problems with the coverage for wide angle lenses. And the YS90 does not need a stronger strobe to trigger it.

Since I don't use TTL that much, I much prefer the variable power settings of the YS90.

 

[buff]

As Sea and Sea says:
The YS0 can be used in TTL mode WITHOUT a sync cord. This what I don't understand:

In TTL(through the lens) mode the camera senses how much ambient light is entering the lens. When a photo is taken, the camera signals the strobe to fire an appropriate light intensity given that ASA 100 film is in the camera. If there is another strobe that is NOT attached to the camera via a synch cord(here the example is the YS90) how does the camera know how to signal the YS90 to "tell" it how much light to put out? The YS90 is fired by light from the main strobe and it can be set to a certain power output-that doesn't sound like TTL to me. Am I missing something here? The main strobe is TTL but the YS90 is manually set-right?? So the total effect isn't true TTL but a combination? Or is the YS90's light output dependent upon how much light is emitted from the main strobe??

Sorry about all the questions in a row but I figure you guys can handle them.

Mike

 

[buff]

Ikelite says:
Note that the TTL slave sensor mode of the Sea & Sea YS-90 must be triggered by a more powerful strobe for PROPER operation.

I think the term "proper" is most important.

Don't foget to look at my prior post on this matter......

Thanks
Mike

 

[Rooster]

Originally posted by buff
Ikelite says:
Note that the TTL slave sensor mode of the Sea & Sea YS-90 must be triggered by a more powerful strobe for PROPER operation.

I think the term "proper" is most important.

Don't foget to look at my prior post on this matter......

Thanks
Mike

Ok, lets see if I can 'splain this. First in TTL the camera does not adjust "intensity", it tells the strobe when to turn on and off. So it controls how "long" the flash is. The camera does not care how it gets its light, either a lot (very strong strobe) in a short burst, or a weaker burst for a longer duration. What TTL does, is measure the amount of light striking the film and turns off (quench) the strobe when it has determined it has enough to properly expose the picture. If two strobes are used, and both are connected with a TTL cord, the camera will fire both strobes at the same time. When the TTL sensor determines that the film has gotten enough light, it will quench both strobes. The TTL sensor does not care if it got more light from one strobe or the other. Now, if TTL determines that the film needs a lot of light, you might get a full dump on the strobe. This might cause an underexposed condition (TTL asked for more light that the strobe(s) could give).
OK, now that I have you thoroughly confused, let's look at the YS-90. Since you plan on using it without a synch cord, the camera will not directly tell this strobe when to turn on, or when to turn off. In "Slave" mode, the YS-90 senses a change in ambient light, (the other strobe firing) and fires it self. It then reads when the ambient light drops, (when the other strobe quenches), and turns it self off. The problem when the other strobe is weaker than it self, is that it will "see" the smaller strobe fire, and fire it self, but because its own light is too strong, it won't "see" the smaller strobe quench. It stays on until it reaches a full dump, even though TTL has said it has enough light. This will over expose your shot.
Hope this helps.
Dive Safe,
Rooster

 

[scorpiofish]

Here, let me try and explain it without confusing both of us.

The camera has a TTL sensor. It senses when enough light is generated to create an 18% gray coverage. The camera then sends electronic signal to cord mounted strobe to "quench" or shut off.

Now you have another strobe working as a slave. When the first strobe fires, the slave sensor tells the slaved strobe to fire also. Now when the two strobes provide enough light to tell the camera it has its 18% gray, the TTL strobe will be quenched.

Here lies the difference between the TTL slave versus just a slave.

If the slaved strobe has TTL capability in slave mode and the strobe is set to slave, it will quench itself when the synched strobe quenches. Hence, they are both operating in TTL mode, no different that if there you used a double synch cord.

If the slaved strobe does not have TTL capability or is set to manual mode, e.g. full, 1/2, 1/4, when the slave sensor triggers the strobe, it will fire a blast based upon the setting. It will not automatically quench when the synched TTL strobe quenches. Hence if you have a TTL strobe and want to use it in TTL mode, the slave needs to be TTL capable also.

Now, I not that familiar with the YS-90, but I believe the slave mode is set to work only in TTL mode, which makes part of my last paragraph moot.

 

[scorpiofish]

Rooster, check your hotmail account.

 

[buff]

....but because its own light is too strong, it won't "see" the smaller strobe quench. It stays on until it reaches a full dump, even though TTL has said it has enough light. This will over expose your shot.


but if my main strobe is set slightly behind the slave won't the slave's photo sensitive area be exposed to more of the main strobe and not it's own light out? just speculating here.


Mike

 

[Rooster]

Originally posted by buff
....but because its own light is too strong, it won't "see" the smaller strobe quench. It stays on until it reaches a full dump, even though TTL has said it has enough light. This will over expose your shot.


but if my main strobe is set slightly behind the slave won't the slave's photo sensitive area be exposed to more of the main strobe and not it's own light out? just speculating here.


Mike

Maybe, maybe not. I believe the YS90 sensors or in its front lens and is designed to read the reflected light of the target. If its own reflected light is stronger than the reflected light of the first strobe, it "may" not see the quench. Since I don't have personal experience with this exact set up I'm only speculating. But moving the main strobe back may only exaggerate the problem.

Rooster