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How to focus underwater?


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#1 Janos Belik

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Posted 02 June 2009 - 05:28 PM

Hello guys,
I am wondering how is the best way to focus in underwater video?
Autofocus? Or zoom all the way out and set focus at for example 0.5 m?

I am using Ewa-Marine housing, which is OK housing,but it is very hard to control manual focus and manual exposure during actual shooting. So the best way is to preset everything or use auto functions. Aperture priority usually works fine for exposure, but what would be the best way to achieve good focus?
Thank you so much for any suggestions or tips.
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#2 Paul Bruening

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Posted 02 June 2009 - 07:29 PM

How are you at holding your breath?
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#3 Daniel Sheehy

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Posted 02 June 2009 - 07:36 PM

Hello guys,
I am wondering how is the best way to focus in underwater video?
Autofocus? Or zoom all the way out and set focus at for example 0.5 m?

I am using Ewa-Marine housing, which is OK housing,but it is very hard to control manual focus and manual exposure during actual shooting. So the best way is to preset everything or use auto functions. Aperture priority usually works fine for exposure, but what would be the best way to achieve good focus?
Thank you so much for any suggestions or tips.

The auto focus tends to get fooled by the housing lens port, so if you're using it, you'll want to be checking the takes carefully.

Depending on what you're shooting, and how the camera is supposed to move relative to the action.. you may be able to use a fixed local length and focus.
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#4 John Brawley

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Posted 03 June 2009 - 02:28 AM

Hello guys,
I am wondering how is the best way to focus in underwater video?
Autofocus? Or zoom all the way out and set focus at for example 0.5 m?

I am using Ewa-Marine housing, which is OK housing,but it is very hard to control manual focus and manual exposure during actual shooting. So the best way is to preset everything or use auto functions. Aperture priority usually works fine for exposure, but what would be the best way to achieve good focus?
Thank you so much for any suggestions or tips.


Are you using a stills camera or video ?

If you use autofocus you'll find that you get a nicely focused shot of your lens port. Sometimes tiny bubbles will gather there and that's enough for the AF to grab onto.

Stick to manual. Get used to it taking longer and beng more difficult to do. Hey..you're filming underwater !

jb
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#5 Richard Boddington

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Posted 03 June 2009 - 09:42 AM

With my underwater system I have an extra wide angle lens that screws onto the front of the video camera. I set the camera for manual focus and zoom in on an object 10ft from the camera, get focus then zoom out to max wide. I leave the camera in this set up and never touch the focus or zoom.

In this set up every thing that goes in front of the camera is in focus, I can hold the camera two inches from coral and it's in focus, or I can shoot some thing 20 ft away and it's in focus.

My housing does give me access to the zoom controls but by zooming in on some thing under water two things happen, 1) The picture gets less sharp 2) The image will bounce around much more vs being on wide.

Most divers will shoot on wide and get the camera closer to the object when possible, i.e. swim.

I do use the auto iris functions underwater and this has always worked great, the camera has no problems achieving proper exposure underwater.

I can't see how auto focus would work underwater at all, the signal sent by the camera would not be able to be sent or received from the camera to the object.

Any way that's how I do it and I have always got very good results.

Keep in mind that since water is so much denser than air it's critical to get the camera close to the object being shot to achieve a sharp image.

R,
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#6 Janos Belik

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Posted 04 June 2009 - 12:16 AM

Thank you guys so much for your tips. I really appreciate your help.
Underwater video is completely new to me, but it is so exciting, so it is worth the extra pain.
Thanks again,
Cheers,
Paul
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#7 Tom Jensen

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Posted 04 June 2009 - 12:33 AM

Don't use lobsters or fish as marks.
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