A Work Commenced September 25 2025
Over the last several years I’ve gained valuable experience with several Canon Image Stabilised(IS) binoculars, including the 8 x 20, 10 x 30 IS II and 12 x 36 IS III. In this review I’ll be test driving Canon’s largest and most powerful IS binocular: the 18 x 50 UD.
Purchased second-hand from a reputable Japanese retailer, my unit was manufactured in Japan, whereas the newer models are now being produced in Taiwan.
The Canon IS 18 x 50 is one hefty piece of kit, tipping the scales at 1180g. Lacking any central hinge, the inter pupillary distance is adjusted simply by rotating the eyepieces. The armouring is in good condition but is not as grippy as I would have liked. Indeed holding it properly is probably the biggest downside to using it and is definitely an acquired skill.
The large 50mm objectives( 4 element)include an ultra-low dispersion(UD) element to minimise colour fringing. The objective lenses are mounting behind an optically flat window so are well protected from the elements. Indeed the binocular is classed as weather resistant(JIS level 4) so can be used even in rainy conditions.
Focus is achieved by moving the objectives back and forth along the optical train.
The focus wheel on my unit still works flawlessly with no free play that I could detect. It operates smoothly and precisely even after all these years: a necessity at 18x since depth of field is very shallow at these high powers.
The dioptre compensation(+\-3) is located under the right ocular lens and rotates smoothly with a decent amount of friction. Though I don’t wear eye glasses, I elected to observe through the eyepieces with the rubber eyecups folded down. Eye relief for the bespectacled is a little disappointing though. I was only able to access a little over half the field using my eyeglasses, for example, with the cups folded down.
The eyepieces on the Canon IS 18 x 50 UD are a complex, 7-element design which includes a doublet field flattening system. Such a complex optical design requires excellent coatings to maximise light transmission. Thankfully this is guaranteed by Canon adopting their excellent Super Spectra antireflection coatings, as well as incorporating Porro II prisms into the optical design.
The Canon IS 18 x 50 UD can be affixed to a photographic tripod if need be. I found this to be useful when adjusting the dioptre compensation on the right eyepiece.
Like the smaller Canon IS binoculars, these are powered by 2 AA batteries. I elected to use rechargeable lithium ions as I have found that they work better in colder environments than their alkaline counterparts and are far less likely to leak even when left in the binocular for prolonged periods. It must be pointed out however, that the lid on the battery compartment must be securely fastened for the IS electronics to work. Indeed I got a bit of a fright during a night walk with the instrument, when the IS suddenly failed. When I got back home I realised that the lid was only loosely fastened, resulting in the batteries not connecting properly to the electrodes. Once tightened down, all was well with the IS system
Optical Evaluation
To be Continued………