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Camera not focusing through flat port with wide adapter lens


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#1 Ferg42

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Posted 25 August 2012 - 05:14 AM

Hi Folks,

OK- not entirely sure if this is the best place to post (or DIY or 3D), but I guess this is where most people might see it. I've been having a strange AF problem-with a sony TD10 3D camcorder. I custom made a pair of wide adapter lenses (by cutting down some raynox wides and sticking them together)- exactly the same thing as is sold by Cyclopital 3d, but i needed a more compact version to fit in my housing. The lenses work perfectly on the camera above water, and give nice sharp images. I took it underwater in my sealux housing (which is not intended to be used with wide adapter lenses), and all my shots came out soft. The more light there was the less soft they were (smaller aperture i guess), but still all soft. So to start with I thought it was AF not working, so i tried manually focussing. Still couldn't get images sharp.
Back to testing at home and I find to my surprise that I have the same problem shooting above water, but through the housing. So it's something about the flat housing glass port that makes the camera unable to focus in combination with the raynox wide lenses (focus is fine without these lenses on)
So I wondered if anyone else has ever come across a similar problem (I guess there no reason why this couldn't happen with a 2D camera), and what it is about the glass that causes this effect. I'm wondering whether changing the type of glass in the flat port would solve the problem....
EOS 7D, Nauticam housing, EOS 5D II, Ikelite, Inon z240, Inon D180, Tok 10-17, 15 FE, 17-40, 105 Macro
Sony HC7, Gates Housing
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#2 SimonSpear

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Posted 25 August 2012 - 11:07 AM

In the past I've had occasional focus problems with flat ports and WA lenses/adapters. I never managed to nail down the exact reason, but I assumed that it was something to do with the port messing with the minimal focus distance of the lens/adapter. I really can't get more technical than that, but I'm sure others can....

Cheers, Simon

Edited by SimonSpear, 25 August 2012 - 11:08 AM.


#3 Ferg42

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Posted 28 August 2012 - 04:50 AM

Thanks Simon,

Well I've confirmed it is indeed the glass. I managed to ram the camera in a different housing and just leave it running, for a quick test in the bath and focus with the wide lenses is perfect. Might have to get in touch with my housing manufacturer and see if they can change the glass for another type. Still weird though. I never would have thought flat glass could have that effect.
EOS 7D, Nauticam housing, EOS 5D II, Ikelite, Inon z240, Inon D180, Tok 10-17, 15 FE, 17-40, 105 Macro
Sony HC7, Gates Housing
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#4 DeanB

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Posted 28 August 2012 - 06:38 AM

Wide angle in the bath!?? I heard it was more super macro ;) lol

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#5 Ferg42

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Posted 28 August 2012 - 06:42 AM

Ha ha Dean! Maybe that was the problem. The water was a bit cold. I thought you were supposed to be on honeymoon- get off Wetpixel this moment.
EOS 7D, Nauticam housing, EOS 5D II, Ikelite, Inon z240, Inon D180, Tok 10-17, 15 FE, 17-40, 105 Macro
Sony HC7, Gates Housing
Visit My Website