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Lens confusion


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#1 jfe

jfe

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Posted 24 January 2018 - 12:43 AM

Hope someone can help me out on this one. I'm looking at buying a macro lens and in particular been looking at the Fantasea range. Here is where I get confused: what is the difference between a SharpEye lens and the UCL range?

Here are the specs on each:

 

 UCL-05LF +6 Macro Lens

•Description: +6 diopter close-up lens

•Bezel Material: Hard anodized aluminum with black hard coating

•Lens Construction: 3 groups and 4 elements

•Lens Coating: AR multi layer coating

•Threads: 67mm (front and rear)

•Dimensions: 74 x 41.1 mm / 2.9 x 1.6 inch

•Weight: 254 g / 9 oz

 

 SharpEye M67 +8

•Lens Construction: 2 groups, 2 elements

•Focal Length/Diopter: 125mm / +8 (Underwater)

•Features a 67mm thread mount

•Lens Coating: multi AR coating + water repellent coating (outer surface)

•Barrel Material: Aluminum with black anodize

•Weight: 135g

•Dimensions: Ø 72mm x 22.5mm (D)

 

All I can make out is the UCL is longer and heavier, but what get me is the construction specs. What does 2 groups, 2 elements vs. 3 groups, 4 elements mean to me as the user? Is the latter a better makeup of the lens though the SharpEye has higher magnification properties?

Any clarification will be appreciated.

 



#2 Tom_Kline

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Posted 24 January 2018 - 01:00 AM

Elements refers to the number of glass elements or actual lenses (100% glass) making up the complex lens (multiple lenses, metal, etc.). Since lens elements are frequently glued together, a group of elements glued together is referred to as a group. For example a simple achromat lens can consist of two elements in one group - a number of long focus lenses made in the past were of this design such as the 400 and 560mm f/6.8 Telyts made by Leitz (company making Leicas before the name was changed).


Thomas C. Kline, Jr., Ph. D.
Oceanography & Limnology
Currently used housed digital cameras: Canon EOS-1Ds MkIII, EOS-1D MkIV, and EOS-1DX; and Nikon D3X. More or less retired: Canon EOS-1Ds MkII; and Nikon D1X, D2X, and D2H.

Lens focal lengths ranging from 8 to 200mm for UW use. Seacam housings and remote control gear. Seacam 60D, 150D, and 250D, Sea&Sea YS250, and Inon Z220 strobes.

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