focus lights... especially in blackwater

[M DeM]

Hi folks-

Having a bit of an issue here and trying to plan for a blackwater dive tomorrow. Issue: focus light.

I do use TTL. So, I use the focus light and focus with AI/Servo. But when I look at my photos they are __blasted___ with light. (see below)


So, here's my question. Am I blasting my focus light too hard? should I turn my focus light down? Or turn my strobes down and not use TTL?

I've read a bunch of blackwater photo tip sites, but is there any other tips that might help?

 

[Chris Ross]

what settings did you use on the image you posted (shutter/aperture/ISO) ? A focus light should not show up on such images unless you have a wide aperture or high ISO. The image posted looks to be within the range to be recoverable in raw and should look fine then apart from the beam of light crossing the image. 300-500 lumens from your focus light should be more than enough for your AF to lock on with, what sort of focus light are you using?

 

[M DeM]

what settings did you use on the image you posted (shutter/aperture/ISO) ? A focus light should not show up on such images unless you have a wide aperture or high ISO. The image posted looks to be within the range to be recoverable in raw and should look fine then apart from the beam of light crossing the image. 300-500 lumens from your focus light should be more than enough for your AF to lock on with, what sort of focus light are you using?

I think you have answered my question...

The focus light was "Fix Neo Light DX" and I had it on 100% -- which meant I was blasting away with 1000 lumens.

The camera was a Olympus TG 5, and I don't have the shot on me so I can't check the EXIF data, but I think it was aperture 8 and auto ISO. But it sounds like I had at least 2x the light I actually needed.

Thanks for the tip!

 

[tursiops]

I would not think TTL would work well for that kind of shot....the image is mostly black, so the TTL tries to provide enough light to give a uniform gray averaged over the image. There is another narrow beam of light coming from the upper right; is that someone else's dive light?

In general, your strobe would completely overpower the focus light....but with auto ISO I'm not sure what is happening. Too many auto things, not necessarily all working for you in the right way at once. I'd get rid of TTL, and auto ISO.

 

[M DeM]

is that someone else's dive light?

yep, I think it is

I'd get rid of TTL, and auto ISO.

I'll try that. So basically just set your ISO to whatever ISO, then use the on-strobe dials or do you prefer manipulating the flash EV?

Thank you for your help!

 

[Chris Ross]

A couple of things with the TG-5. First it has two apertures, f2 and f2.8 at the widest zoom. f8 is achieved with a neutral density filter. At f2 or f2.8 you would want to have a lower power on your focus light as there is a good chance of it showing up. To help with that use the lowest ISO offered. The other issue is that the camera does not have manual settings so you can't set shutter speed. If you have on forced flash it will bottom out the shutter speed at 1/30 which is pretty slow.. 1/30 at f2.8 ISO100 would have a reasonable chance of picking up the beam. Drop your output down to 25% power or so.

I would normally suggest not using f8 as it wastes light, being just an ND filter, but if you continue to see the torch beam then you may need to use f8. to allow you to pick aperture shoot in Av.

Shooting in manual should be preferable, you can set the TG-5 flash to manual so it will only act as a trigger.

 

[M DeM]

Thank you!

 

[M DeM]

I dimmed my focus light, put the aperature way up to f22, ISO 100 and used TTL (one strobe) and at least I"m getting some color now! Still a LOT to learn!