Focus light

[ShoalDiverSA]

The camera auto-focuses using the infrared focus lamp. It is a good idea to augment the built-in focus lamp with an external focus light (white light). I have found that my camera (Samsung) struggles to focus under overhangs using the built-in focus lamp.

Cheers,

Andrew

 

[chippy]

I tell a lie, it was on Backscatter.com and it was $399!!!:-

Light & Mtion Focusing Light

 

[ReyeR]

Really? Theoretically it should work up to about 2 meters - Red and Ultraviolet are absorbed at 5 meters. Anything longer than 2 meters shouldn't be a problem as the depth of field from 2 meters to infinity is quite easy to get at F8 or even F5. Focusing and depth of field become problematic the closer you get - especially macro work - but then I would have thought the infra-red would handle it. It IS however why I use fixed focus lengths X F stop settings in My Mode (it also speeds the shutter delay up as the camera doesn't have to auto-focus). I could have a completely wrong take on this - these are just my 'thoughts' ! (which is what you originally asked for!!)

One last thought - how does the C-5050 auto focus if you are not using a strobe and just the internal flash? It can't be on the pre-flash - there's not enough time in between the pre and main for the camera to focus?!

By the time the built-in autofocus light of the camera goes through the polycarbonate of the housing and through the water it's too weak to do much good. Also at close distances you start getting a parallax error and the light shines above the focus brackets. I also use a flash block in front of the housing which partially blocks out the focus light as well.
The C5050 focuses by 'contrast detection' and, as you correctly pointed out, not with the pre-flash.

 

[ReyeR]

I tell a lie, it was on Backscatter.com and it was $399!!!:-

Light & Mtion Focusing Light

Ah yes, the Sunray Mini Modeling Light. Very, very nice light. But a bit of an overkill at $400 for a focus assist lamp, don't you think :11:???

 

[ReyeR]

Tried an Ikelite PC Lite (4xC batteries) on the weekend. I didn't find it bright enough to make an effective difference to the focusing speed and accuracy. The search continues....

 

[alcina]

Tried an Ikelite PC Lite (4xC batteries) on the weekend. I didn't find it bright enough to make an effective difference to the focusing speed and accuracy. The search continues....

Just got my UK Mini Q40 - from those who recommended it they love it. Have no handle yet and haven't been in the water for...oh my god, can it be only 5 days, seems like a month... so can't give you first hand info yet...

 

[kdietz]

I'll be interested in how the Q40's worked for you....I'm thinking about them also...maybe a pair of them?

Karl

 

[fpoole]

I use a simple UK Mini Q40 with small bubble wrap in front of the bulb.
I've Plastic tied it to the strobe on one camera, and then on the other to the camera/tray .

It's a strong enough light to allow focusing and the bubble wrap diffuses it so as not to create a "Hot Spot" with the pic... just turn it on, leave it on or twist it off as needed, but it seems to work fine. No hot spots, again with the bubble wrap up against the clear inside lens..
just take out the reflector, cut a circle out of that fine packing bubble/foam and pop it in... then tie the light to with plastic ties to the strobe or tray or camera, whatever works best...
I would also recommend getting the fishing wire clasps/leader to work as a back up to secure your light if it falls off... all fishing stores have them...

Hope that helps.....

 

[ShoalDiverSA]

fpoole,

How about a piture of your focus light?

Thanks,

Andrew

 

[ReyeR]

It's a strong enough light to allow focusing and the bubble wrap diffuses it so as not to create a "Hot Spot" with the pic...

fpoole, underwater, how far would you say you can be from the subject and still get a decent patch of light on it and help the camera focus? 1m (3ft)? More? Less?