Loupes: a closer look…

There seeems to be a large variation in quality and prices (from £5 to £100 or more) when it comes to loupes (a loupe is a common term for a hand lens or magnifier). Loupes are used extensively for biology field work, geology, etc. as a portable way to get a good look at specimens. We often buy them online, without really getting to compare them, so I thought I would buy a few from different manufacturers and see what the difference was. Full disclosure: some of the products which make the grade are made available for sale on my website www.micro-science.co.uk

Most of the loupes tested were 10x magnification as this is something of a performance sweet spot. Higher magnifications tend to have very small field of view limiting their usefulness. Lower magnifications do not really get you close enough.

I looked at image quality (across the field and contrast), build quality and value for money when comparing the different models. A quick summary is shown below.

Below the summary table is a little more information, including an explanation of what is a “triplet” lens. If I can take some representative images through the triplets at some point, I will include them later.

	Name	Magnfication (claimed)	LED	Price (approx RRP)	Lens diameter (and actual viewing area) mm	Rating	Comments
	Illuminated loupe	10x (or 40x?)	Yes	less than £5.00	25(23)	1/5	- Poor build quality (it fell apart) - Poor image quality - severe cushion distortion
	Jewellers loupe Triplet 10 x 21 mm	10x	No	£10.00	21 (19)	2/5	- Poor build quality - Lens is actually a singlet not a triplet + image OK (centre) - severe cushion distortion
	ARC Triplet 10 x 21 mm	10x	No	£15.00	21(19)	4/5	+ Good image quality + Good build quality + It really has a triplet lens + Leather case - No LED
	LED Loupe 10x21mm	10x	Yes	£25.00	21(19)	5/5	+ Excellent image + 6 x LED ring + Good build quality + Metal housing + Leather case - smaller flat field-of-view than rivals
	Schweizer Tech-Line 10	10x	No	£30.00	21(21)	5/5	+ Excellent image + One-handed opening + wide flat field-of-view - some colour fringing at edges - Plastic housing - No LED
	Schweizer Tech-Line 3 + 5	3x + 5X	No	£35.00	38 (35)	4/5	+ Huge 35mm field-of-view + 3x lens gives a big sharp image + Comes with a lanyard - Image not as sharp to the edges with 5x or both lenses combined - No LED - singlet lenses
	Schweizer Tech-Line Handheld 10	10x	Yes	£55.00	20 (20)	4/5	+ Good image quality + LED + Long battery life - some colour fringing at edges - No lanyard attachment point

Triplet lenses

A simple lens (singlet) magnifies but tends to give a distorted image due to inherent aberrations. Triplet lenses were designed to overcome some of these problems and give a distortion-free image, especially at the centre of the field-of-view.

Very high quality lenses (Aplanats) are capable of correcting distortions across the entire field-of-view.

More information is available on triplets (wiki) and optical aberration (wiki).

Many of the loupes sold on line claim to be triplets. However, buyer beware. A couple of the loupes were superficially very similar and labelled identically (Triplet 10x 21mm). However, the quality of the images and internal lenses were very different.

Magnification

Some of the cheaper loupes are creative with their magnification specification. One was sold as a 10x and arrived labelled as a 40x. It was probably 10x or less.

Conclusion

It was a pleasure to test some good quality loupes which made viewing specimens much more relaxing. I would recommend either of the loupes which scored five stars for biology fieldwork. The Tech-Line folding 10x is light, comfortable and has a very wide flat field-of-view and feels quite durable even though it has a plastic body. However if you spend a lot of time in dark woods and want a light source, then the the LED loupe triplet 10x is a good option. A good loupe should last you many years if looked after correctly and you will spend a lot of time peering through it, so it is worth getting a decent one and putting it on a lanyard so you don’t lose it.

The larger 3+5 loupe and handheld models from Schweizer felt a bit plasticky given their premium price.  However they could be useful to use at your desk or when looking at larger items such as stamps or coins.

If you are buying elsewhere, just watch out for anything with screw holding the axle in place as this seems to be an indicator of poor quality. As is often the case, you pretty much get what you pay for.