i did some testings to understand better what counts with 10x loupes.
This has by no means the claim to be scientific but may be of interest for someone.
The loupes i compared are the following:
left from top
- Nikon 10x
- Bausch & Lomb 10x Hasting Triplet
- Zeiss / Winkel D80 Apl. 10x
right from top
- BelOMO 10x Triplet
- LED LOUPE Triplet 10x-21mm - Dual Light - White/UV
- GemOro 10x18mm Hastings Triplet
About the magnification there is not a big difference between them.
Pictures taken with Canon 5D and Nikkor 55/3.5 aperture 8.
Crops from center:
Bausch & Lomb
Personally i love the Nikon because it is really sharp with great contrast and the case is very lightweight an slim but the lens the smallest of all.
The Bausch & Lomb is kind of a standard, really good an not expensive.
The Belomo is also really good but heavy, i heard it´s only 9x.
I was really surprised by the LED loupe. The lens is big and really sharp and must be achromatic and aplanatic. The light option is a big +.
I think the Gemoro must be a fake, quality is so bad - must be a single lens.