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Angle of view underwater


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#1 fish323

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Posted 30 January 2019 - 08:31 PM

Hi

I have had a look and can't find an answer that does not entail me to do some algebra that I would probably get wrong. 

What is the equivalent of 24mm on a 1 inch sensor underwater, thanks? 



#2 ChrisRoss

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Posted 30 January 2019 - 09:14 PM

Flat or dome port?  crop factor is 2.7x so divide 24mm by 2.7 = 8.8mm behind a dome port or divide by 1.25  to get 7mm behind a flat port.  Keep in mind that the edges of the field would be rather poor with 24mm field of view behind a flat port.  This link explains about flat vs dome port:

 

https://oceanity.com...me-port-theory/



#3 fish323

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Posted 30 January 2019 - 10:16 PM

Thanks for the reply Chris. It is a Sony RX100V in a Sony MPK-URX100A Underwater Housing. I just want to know what my 24mm will become once it is in the case underwater.



#4 dreifish

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Posted 30 January 2019 - 10:38 PM

In a flat port, it will become something akin to a 32mm. (Multiply by 1.33) Behind a dome port, it would retain its land angle of view.



#5 fish323

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Posted 30 January 2019 - 11:01 PM

In a flat port, it will become something akin to a 32mm. (Multiply by 1.33) Behind a dome port, it would retain its land angle of view.

Thanks very much. 



#6 Interceptor121

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Posted 31 January 2019 - 12:34 AM

Generally under 35mm equivalent you have pincushion distortion if you use a flat port

 

This is bearable in the range 28-35 and awful in the range 24-28 so if you are thinking about 24mm * 1.33 = 32 still good think again


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#7 fish323

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Posted 31 January 2019 - 01:08 AM

Generally under 35mm equivalent you have pincushion distortion if you use a flat port

 

This is bearable in the range 28-35 and awful in the range 24-28 so if you are thinking about 24mm * 1.33 = 32 still good think again

Could you point me in the direction of some examples of this please? While you are at it could you suggest an underwater filter that is not insanely priced? I was thinking of a Seafrogs/Mekion one. Thanks.



#8 Interceptor121

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Posted 31 January 2019 - 01:18 AM

Filters do not have anything to do with field of view what you need to restore is something like the Nauticam wetmate for compacts


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#9 Interceptor121

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Posted 31 January 2019 - 01:25 AM

Look at this post to understand the issue

 

https://interceptor1...vancedcompacts/


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#10 fish323

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Posted 31 January 2019 - 04:01 AM

Filters do not have anything to do with field of view what you need to restore is something like the Nauticam wetmate for compacts

I know that. Can you recommend a reasonably priced colour correction filter?



#11 Interceptor121

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Posted 31 January 2019 - 10:58 AM

Get a magic filter it is available for threaded ports M67 like your housing this is optimised at 7m for something deeper look at URPRO or Keldan nothing is cheap


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