Need help for fuji f420 and Epoque ES-150DS flash

[Manogr]

Hello all..

I just received my housing for the Fuji Finepix F420zoom cam and the Epoque ES-150DS flash with Epoque Fiber-Connector (velcro in front of flash). I really need your advise regarding the settings on the cam and strobe for my underwater photos...
The strobe has a selection button with: Guide No: 3, 6, 9, 12, 15. What is the Guide number ? What should I use?
Moreover what settings should I have in my cam? Auto flash ? Manual ? EV ? How the optical sensor can know that I use an extra flash ? How I avoid overlighted photos? etc etc

I know that practice is what I should do but as I have a nice liveaboard trip coming next week I really want to gain from your experience in order to know at least some basics!
Even if you don't have the same cam I am sure that you can help me!

For the cam and housing: http://www.camerasunderwater.co.uk/d_stills/fuji/wpfx420.html
For the strobe: http://www.camerasunderwater.co.uk/d_stills/flash/es150ds.html

Thanks in advance,

Manogr

 

[Jason B]

The guide number is used to calculate the required aperture setting for a certain distance. If you had a subject that was 3 feet away and you had your guide number set on 6, then the correct aperture can be found by dividing the guide number by the distance, or in this case, 6 (guide number) divided by 3 (distance). 6/3=2...so the correct f-stop for this photo from 3 feet with the strobe guide number set on 6 is a 2.
You might not get the depth of feild you want with an f-stop of 2 so let's crank up the strobe power so we can close down the aperture more to allow a better depth of field. Lets go with the highest setting. Now with the strobe set on a guide number of 15 and the subject still 3 feet away our calculation becomes 15/3 which gives us an f-stop of 5. An f-stop of 5 is smaller than an f-stop of 2 and will yeild a better depth of field. That's how the guide number works.

 

[Jason B]

How is the camera going to know that you have an external strobe? That fiber optic cable coming from your strobe will attach over your cameras internal flash. When ever you take a picture with the flash on, the flash from the camera will not illuminate your subject because it has been covered by the velcro attaching the fiber optice cable. Luckly the light from your cameras flash will be sent through the fiber optic cable to the external strobe where there is a light sensitive sensor. When this sensor detects light (because you took a picture and your internal flash fired, sending light throught he fiber optic cable) the external strobe will be triggered to fire.

 

[Jason B]

I just searched for your cameras manual online. It looks like the only manual controls you can adjust are white balance and EV. As for the white balance, it does not look as though you have a custom setting. You may want to try the "shade" position. You're going to have to play with this one underwater to find the right setting.

 

[Manogr]

Wow Bubble you are more than helpful!

From what you understood from the manual is there is a possibility to change the f-stop ? Or this is performed with the EV? what is the EV in general ?

Thanks...

manogr

 

[Manogr]

One more question..the flash (of the cam) should be in auto ?



Manogr

 

[Jason B]

Looks like you can't even change the f-stop or shutter speed, so yes, the EV control will give you some exposure control if the camera doesn't select the correct settings.
If the camera's exposure meter decided that a particular photo needed an f-stop of 5.6, yet the resulting picture was to dark...no problem, by setting your EV control to +1 you are telling the camera to increase exposure by 1 stop. It will do this by adjusting the aperture, shutter speed, or a combination. Same holds true if it was over exposed, dial the EV control down to cause the camera to under expose the photo by however much you dial in. Again, you'll probably have to play with this awhile before you get a feel for how much compensation is required (and it will probably change with depth and distance). As for digital photos...slight under exposure will be easier to correct with imaging software (photoshop elements) as apposed to over exposure.

 

[Jason B]

The flash setting will be determined by how you set you external strobe. If you have you strobe in the "fire always" mode, then you can leave your camera flash in auto. If you have you external strobe set for "ignore pre flash", then you can set it in red eye reduction mode.

 

[Manogr]

The flash setting will be determined by how you set you external strobe. If you have you strobe in the "fire always" mode, then you can leave your camera flash in auto. If you have you external strobe set for "ignore pre flash", then you can set it in red eye reduction mode.

Thanks man! I know that I have to practice but it is extremely better to have an idea before practicing! For example your EV comments were more than helpful!
As my flash have both options (on and ignore pre flash) is there a suggested way ? Should I put it on red eye for any reason or just leave it in auto where it fires only once?

Thanks...Manogr

 

[Jason B]

Good question, and I'm not really sure that picture wise it will make a difference. My only thoughts on this are that if the pre flash is required then the battery life in the camera will be shortened.