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londonsean69

Member Since 09 Apr 2007
Offline Last Active Mar 30 2018 03:18 PM
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Topics I've Started

Effect on focus distance of being underwater

06 March 2018 - 10:33 AM

Evening all (well, it is here)

 

Forgive me for what could be an obvious question, but my knowledge of optics is a little lacking.

 

I have just acquired a Saga +25 macro lens (as well as a +10) for use with a Sony RX100 (MK 1). I have some very small targets in mind :)

 

I have tried this out on the coffee table, and to achieve focus, the port is resting on the table. Naturally, I can see this being an issue UW - I am not particularly enthused by the prospect of squashing a nudibranch or pygmy seahorse or damaging their habitat.

 

My question is: How much if any, additional working distance will I gain by being underwater? I don't have access to a pool to test, although I guess I could always have a go in the bath!

 

Thanks in advance

 

Sean