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Does the camera lense to housing lense distance effect image clarity?


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#1 Splint

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Posted 05 September 2012 - 03:22 PM

Hi,

I hope this is not too stupid of a question but I'll ask it anyway. A while back I did a dive and took some photos. When I looked at the photos on the compuiter screen the visability was noticaby lower than what I remeber it as being on the dive. I'm confident that the lenses on the housing and the camrera were clean and not inhibited in any other way such as fog. I dont think the issue I'm talking about here is backscatter as I've experienced that as well and it's different again.

Could the reason for the lower visability be caused by the air gap between the lenses of the camera and housing being small? Whould a larger air gap from an extended dry lense improve the clarity of the image?

Cheers
Splint

#2 Steve Williams

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Posted 05 September 2012 - 08:14 PM

Hi Splint,
I'm guessing the small air gap is not your problem. Much more likely would be a large water gap. If the distance between your camera and the subject is too big it can look like you describe. A lack of light can also fool our eye. Can you post an image so we can see what you're dealing with?

Don't worry about asking dumb questions here. If this stuff was easy everybody would be doing it. Posted Image

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#3 Splint

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Posted 05 September 2012 - 11:53 PM

Thanks Steve,

This is one image I took at Truk Lagoon. Obviously a strobe would improve the picture quiet considerably as would appropriate filters. The picture was taken with a Nikon Coopix 5900 5.1Mp, a fairly low end camera compared to what a lot of folks here would be using, but non the less does take decent photos.

I've since invested in a pair of Sea and Sea YS-02 strobes as the Nikons internal strobe is near useless inside the Ikelite housing, haven't had a chance to try them out though.

Cheers
David

Attached Images

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Edited by Splint, 05 September 2012 - 11:54 PM.


#4 MortenHansen

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Posted 06 September 2012 - 05:21 AM

Subject-Lens distance is the issue here. It is very difficult to take photos of objects larger than 50cm with a "normal" compact-camera, the problem is that in order to fit something larger into the frame you have to back up, lets say 3-4m. This distance is way too big.

My best advice for you is to get close, really really close (50cm or less) and concentrate of nice soft-corals, coral colonies, lionfish etc- Then shoot from below and upwards instead of downwards.

If you really want to take pictures of bigger things you should set your white-balance manually, turn off your flash, and underexpose by about half a "stop". Just use your exposure compensation for it. Unfortunately its very difficult to do great wide-angle shots without a wide-angle lens :)

Have fun!

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#5 tdpriest

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Posted 11 September 2012 - 03:06 PM

Steve and Morten are right: the optical arrangement of the camera, lens, housing and port become critical with dSLRs, wide angle lenses and dome ports, but are usually handled pretty well in compact systems.

Strobes wouldn't have much effect on the Truk image: the secret, to strobes and to underwater photography in general, is to get close...

... and then realise that you're still too far away!

The eye and the camera don't work in the same way, and don't see the same things: the preview (or viewfinder) and review images are much more helpful than the eye's impression of the scene.

Edited by tdpriest, 11 September 2012 - 03:09 PM.