Too Much light

[UK Jacko]

Hi Everyone,

I'm new to this underwater digital stuff, I arrived kicking and screaming from the dark age of film photography a short while ago. (I can't believe the stuff I don't know)
I have a Fuji F11 with a Epoque ES-230DS auto strobe. (the one with the new battery door and fingers crossed, too date it hasn't flooded)
I can't seem to power down the strobe enough to avoid over exposed pics. It appears that the auto on the camera isn't talking to the auto on the strobe, I was of opinion that they would!
I have the camera set on auto with the flash turned permanently on. The strobe is set to the lowest auto setting. Is this correct? Or should I go to manual and adjust the light with aperture/shutter speed/ISO? If this is the case does anyone know what settings I should go for.
I'm also a little confused with ISO. With film the higher the ISO number the grainier the pics become, but I've read on these threads that you talk of noise and not grain. Are the two much the same thing, or is this something else I need to learn about.?
I'm sorry if I seem a bit thick, but that's probabely because I am.

Thanks

UK Jacko

 

[Warren_L]

Yes, you are correct on the ISO - with digital, the lower the ISO, the better the image quality tends to be with lower noise and better dynamic range.

It sounds like there are a number of things going on here. If you're using the internal flash with the strobe, you may want to block out the flash so that it does not light any of your image. If you've got a diffuser on the housing, some black tape on the diffuser or on the housing itself. Just make sure that there is light to trigger the strobe (presumably your strobe is optically triggered).

You may want to avoid using auto settings as well, as they can be somewhat unpredictable. If your pictures are getting blown out, set your ISO at a low level (100 or 200 perhasp, depending on your camera). Use a fairly high f/stop and a low power setting on the strobe to begin with and adjust as necessary. If the strobe is blowing out your shots, the shutter speed shouldn't really make much of a difference, as it will affect the amount ambient light.

 

[arenny]

Warren,
(don't mean to hijack the thread) Is it better to use ISO 100 than 60? I know 60 is better quality but I heard 100 has better color saturation? Thanks!

 

[Warren_L]

Warren,
(don't mean to hijack the thread) Is it better to use ISO 100 than 60? I know 60 is better quality but I heard 100 has better color saturation? Thanks!

In general, I would say yes, but it really depends on the sensor. With a lower quality sensor, there may be greater improvement in what you get by going down to ISO 60, but with a high quality sensor, the difference may not be as significant. YMMV. But in general yes, and as I'm sure you can appreciate, going down to a lower ISO means sacrificing something somewhere else - as in slower shutter speed, larger aperature, more strobe power, etc.

 

[justleesa]

how close was your strobe to the object you photographed?

 

[UK Jacko]

The strobe distance varied from half meter to 2 meters.
As a result of reading Warrens reply I've had another look at the results in the camera and it seems the auto setting may have been the problem. It has set the ISO generally to 200, but some are 400. All these seem to be with an F stop of 2.8.
So I think I need to go and get wet ASAP and set up for manual with ISO 100 and play with the F stop until I get the right results.
Thanks to everyone for the help so far.
I suspect I'll be back with more daft questions next week when I've been diving.

Thanks Again

Jacko

 

[oly5050user]

The strobe distance varied from half meter to 2 meters.
As a result of reading Warrens reply I've had another look at the results in the camera and it seems the auto setting may have been the problem. It has set the ISO generally to 200, but some are 400. All these seem to be with an F stop of 2.8.
So I think I need to go and get wet ASAP and set up for manual with ISO 100 and play with the F stop until I get the right results.
Thanks to everyone for the help so far.
I suspect I'll be back with more daft questions next week when I've been diving.

Thanks Again

Jacko

I don't know what the guide number for the strobe you have is but you can start out with an ISO of 100 and aqa f stop of 5.6 for a distance of 3/4 feet..distance of 2 feet go to f 8...this is with a shutter speed of 160 /200

 

[RonFrank]

It has set the ISO generally to 200, but some are 400. All these seem to be with an F stop of 2.8.
Jacko

First problem solved. Your camera is exposing for available light, your strobe maybe powered down, but that means little as you are still flooding the subject with your ISO value of 200/400.

The second problem I see is the statement "It has set". You need to be in control of the settings even if you choose to use Aperture priority for example. Letting "IT" choose your settings, and adding a flash is a receipt for problems as the camera has no clue the flash is there, and the flash has a limited amount of adjustments.

 

[RonFrank]

Warren,
(don't mean to hijack the thread) Is it better to use ISO 100 than 60? I know 60 is better quality but I heard 100 has better color saturation? Thanks!

Color saturation has little to do with what ISO you choose, rather more to do with if you are exposing properly. A properly exposed image will have the same color saturation at both ISO 60, and ISO 100, but the image at ISO 100 will exhibit a bit more noise.

Sensors are basically calibrated to capture light using ONE setting, the lowest in general. To increase sensitivity they increase gain. Increasing gain increases noise.

I'd choose your ISO based on your lighing conditions, and what aperture (DOF) you think would be best for the given composition.