Lens confusion

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jfe

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Location
Qatar / South Africa
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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 heavyer, 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.
 
Lenses are complex beasts. Typically the best lenses have more elements (chunks of glass) because they are worried significantly about things like fringing and chromatic aberration. Elements are often glued together into a group to simplify building the lens. I have tested neither lens but typically fewer elements means more optical irregularities than with more complex lenses but also lower costs. Remember we are shooting in a really ugly environment most of the time so small optical irregularities like fringing might not be worrisome.

Cheers
Bill
 
https://www.shearwater.com/products/swift/

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