cruel_world

After having an Ikelite housing for my 20D i was a little disapointed in the port/lens selection of ikelite. mainly it was limited by my lens diameter. ( Sigma 12-25mm EX ) to be specific. I mave heard Aquatica has the largest port opening out there and the Sea&Sea port system looks great. But wat are the exact diameters of the openings. Additional comparisons would be welcome. Cheers

Fill is just that, Bringing the exposure overall up. This provides 3 benefits. The main strobe doesn’t have to work as hard. The shadows are reduced and the angle of light is increased. Unfortunately the YS25dx is only good for the first 2 since the guide number is only 15 underwater compared to 30+ for the 125. However for reducing the shadows I figure it would be good for 2+ stops. That’s Fstops for light. As for just using a single strobe. Start out with that. There is no need to over complicate your experience. 2 strobes will primarily give you a wider angle. But one strobe with a defuser will as well. It will just loose 1 or 2 Fstops of lighting ability. But with a good powerful single strobe it is usually not a problem except at the extremes. As for fill, 1 strobe (defused) for fill on a slave ( that’s a flash that is fired by detecting the flash of a primary ) combined with a good primary should provide some good shadow control. The only drawback of a slave as apposed to a TTL secondary is that the TTL of the primary must be adjusted down to take into consideration the added light of the slave. This is because when the primary fires in TTL mode it emits a preflash ( very briefly ) that is used to determine the over all primary flash amount. Because the slave should be set to fire only on the exposure flash ( the second burst of light from the primary ) the slave will not fire on the preflash; therefore the camera emits a full TTL charge for the primary with out regard for the added light the slave is bringing to the party. QED Needless to say, This combination only works with a Slave that is fully manual. and a Primary TTL that can be adjusted to compensate for the slave. Cheers.. Bill Russell

Hmmmm. Well, we first need to know what lens you were using, What Lens port, and if you were using a Diopter or not. Lenses that can not focus on there own < then 12in from the Film Plane need to use a close up diopter +4 to achieve Focus in a dome port. This is because a dome port ( underwater ) acts like a big lens bringing everything to focus at around 12". See Ikelite.com port selections for an explanation of this. Bill Russell

I'm going to YAP in a few days, I have an Ikelite 20d and 1 DS125 ( Second Crashed ) Additionally I have a Sea&Sea ys25dx i plan on using as a fill flash since I cant shoot with 2 125s. The YS25DX will be set in Optical Slave. and will hopefully work without the optical sync cord. I have one but it works without on land aswell just using the sensor in the flash body. I am hoping this combination will work. I realize I will have to adjust TTL down to make up for the fill. I realize this is an odd combination. What are your thoughts on the ys25dx as a fill? Cheers Bill Russell