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DIY LCD magnifier - optics question


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#1 ProfF

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Posted 21 September 2013 - 02:19 AM

Hi,

 

With the advances of age, my near sight is going down. I realized recently that I shoot underwater with arms fully extended, otherwise I don't see the LCD in focus :-(  While this extends my reach, it does not help the quality of the shooting. 

Nauticam recently came out with an LCD magnifier that has diopter adjustment (which presumably can solve my problems) -- see http://wetpixel.com/...r-and-sunscreen

 

However, my housing model (NA-EPL3) is not supported for this magnifier, and as far as I can tell it would clash with some of the control buttons that are on the screen periphery (in the newer housing models they moved these further from the screen).

I am thinking of building a DIY version. Designing a shell that fits the screen and button layout was easy (and I plan to print one).

 

Magnifier.png

 

The question what type of glass to put on the viewing end (right now the top holds a 55-52mm stepdown ring (in light gray), that allows me to put in 52mm filters. One option is to use standard close-up filter (say +10). However, I am not sure how well this will perform underwater and it definitely would not be adjustable.

 

Any suggestions on a better mechanism? 

 

Thanks

 

Nir

 


Olympus E-PL3, Nauticam NA-PL3, Olympus 9-18mm, 12-50mm, 60mm lenses, Sea & Sea YS110a, YS01.

#2 lisperit

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Posted 24 September 2013 - 01:49 PM

Hi , I have the same problem so I ordered and tried the Nauticam LCD magnifier for my RX100 housing.

Beautiful object but the dioptric adjustment is not enough for me, I need  to add a +2 lens to it.

The problem is the small refraction difference between glass and water: single wet lenses loose 2/3 of refraction power.

You will need about +20 ,+ 25 underwater to have the same effect of a +7 , +9 in air using a single wet positive lens but such  a lens is not easy to find.



#3 ProfF

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Posted 25 September 2013 - 06:45 AM

I am aware that lenses lose between 1/2 to 3/4 of their power due to differences in refraction index. I am thinking of sandwiching a diopter lens between two clear ones (UV filter). If I can get this contraption to be waterproof, the diopter should not lose its power, as far as I understand. (This how Subsee lenses are built.) The optics are terrible with cheap filters, but since it is only a viewfinder, this will not show in the final images :-)

 

I am wondering if there is a way to make the diopter power adjustable. Any ideas?


Olympus E-PL3, Nauticam NA-PL3, Olympus 9-18mm, 12-50mm, 60mm lenses, Sea & Sea YS110a, YS01.

#4 lisperit

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Posted 25 September 2013 - 12:15 PM

Nauticam magnifier has a simple system : "screw in, screw out" of the entire "optic cell" , about one inch of movement.