If we’d been able to begin walking that morning we would have had enough time to tackle the north ridge on the same day, but by the time we reached a saddle beneath the Apprentice, an easy-to-reach 1,678m highpoint a little to the northwest of Mount Technical, there wasn’t enough daylight left. A little below us, nestled in a broad cirque, lay another tarn that looked like the perfect spot to camp.

Down at the tarn we set up camp behind some sheltering boulders, enjoying smoked chicken, pasta and veges a la Barnett. There was to be no sunset though as the clouds really piled in.

The more light that reaches your eyes, the better you can see. Anti-reflective coating (also called “AR coating” or “anti-glare coating”) decreases the amount of light that is reflected off the front and back surfaces of your eyeglass lenses. This lets more light pass through the lenses and reach your eyes.

At one point a packless wrecky was needed to navigate seemingly bottomless bluffs, but after three or so hours we descended below the cloud base and saw beneath us a tiny yellowish orange box sitting beside a tarn. Brass Monkey Biv – its location was as evocative as its name.

Shaun Barnett had some unfinished business on an 1,870 metre crag known as Mount Technical on the Lewis Tops in the Lewis Pass National Reserve. He’d climbed it before via the west ridge, but wanted to have a crack at the more technical north ridge. My boots had never trodden anything in the Lewis Pass area, so anything was worthy of a look as far as I was concerned. Although the weather forecast indicated a change coming, we hoped the clear weather would last a bit longer.

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Down below 700 metres at the hut though, a new and evil challenge very quickly emerged – sandflies – hordes of voracious little monsters that made trying to follow deer trails while drenched seem like a luxury. Once behind a closed door in dry clothes, including long trousers, long sleeve shirt, glacier hat and lashings of insect repellent, things perked up noticeably. The first other people we’d spent any time with on the entire trip turned up at the hut soon after us – two English brothers. Alistair was a rural vet based at Rotherham in Canterbury, Chris a bridge designer from Chicago, so interesting conversations were had.

It seemed like the weather had been sunny and scorching for weeks. Drought conditions were being endured at various points around the country and the fire hazard was set at high.

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Lewis Tops track

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Although the weather hadn’t been conducive to any serious climbing, clearings in the clag during the afternoon encouraged us out to explore the terrain around the Biv. More tarns cropped up as we wandered over the folds in the landscape.

The majority of lenses with anti-reflective coating have a very light tint, which is usually green or blue. The color depends on the brand of coating that’s on your lenses.

In very limited visibility it took us longer than expected to find our way across rugged, sometimes narrow and exposed ridge tops to the Biv. This image - Heading south west along the craggy ridge towards Brass Monkey Biv

Mt Norma to MtTechnical

And a steep scramble leading up to a 1,674m highpoint to the west couldn’t be ignored. Once on top, again we were rewarded with beautiful views. The cloud base smothered the last 50 or so metres of distant Mount Technical, but everything lower than about 1,800 metres was in view. This image - A view east from the 1,674m high point, back to Brass Monkey Biv (lower right) and the route we took that day back to Mt Technical - top right, shrouded in cloud

Next morning we just had an easy walk, still in overcast conditions, on a well trodden trail beside the Nina River which, after a couple of hours, reached a swing bridge crossing the Lewis River. Having met Alistair and Chris was very handy as they had a vehicle parked at Palmer Lodge beside SH7. We arrived at the highway ahead of them, but hitching the 10kms back up to our own vehicle had proved a no go. If only I’d figured out how to call the Tardis, just like Doctor Who does when he needs a lift somewhere, then we could have arrived via yellowish orange two metre cube. As it was, Alistair’s Toyota Surf sufficed.

It wasn’t to be. Next morning the weather had only worsened, so our thoughts started to dwell on the potential for swollen rivers preventing our escape. Our best option, other than retracing our steps over uninviting tops, was to descend into Duchess Stream, follow deer trails mostly on the true right to begin with, then cross the stream and sidle upwards to avoid a steep narrow gorged section. It was wet, slippery, arduous going. This image - Descending in to Duchess Stream

Back down in the snug shelter of the Tardis we enjoyed many brews, several forms of chocolate and then another good sized dinner as we waited to see what the weather would bring. If it improved we hoped to sidle around ledge systems to have a crack at the 1,700m Grand Duchess. In the craggy but open terrain there are many options open in every direction, at least if conditions permit. This image - A view from the 1,674m high point to the west of Brass Monkey Biv. Here looking south west down the valley leading to the Christabel Track

Most premium AR lenses include a surface treatment to seal the anti-reflective layers and make the lenses easier to clean. These treatments also repel water so you won’t get water spots on your lenses. Some lens surface treatments repel both water and oil from your skin.

Post script: Just when it seemed that the ‘leader of the free world’ Donald Trump had completely eroded all forms of moral fibre, my faith in humanity got a boost on my return to Wellington. Upon unpacking my gear I discovered that I was a goose, having left my fabulously NZAC logo emblazoned fleecy hanging from a rafter at Nina Hut. But then an email from Ashlee at NZAC Central Office informed me that a good sort from the Nelson Tramping Club had let her know that he’d carried a blue fleecy out with him from Nina Hut. He’d checked the Hut book and had a hunch it belonged to Shaun or me. I gave him a call. He refused payment for postage and a few days later it arrived, nicely folded. Thank you David Renwick – your moral fibre is up to free world leadership standards, unlike someone else’s.

Because the north ridge of Mount Technical is graded a 3, we carried a rope, harnesses and some rock anchors. We also had a tent and other related paraphernalia, so the weight of our packs had the sweat streaming out of us in the bright sunshine as we made our way along the tops, passing numerous inviting looking tarns. The north ridge of Mount Technical was soon in view, looking suitably craggy. This image - Mt Technical, right, with the Opera and Libretto Ranges to the east

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Light is critical for good vision. When light enters your eye, it hits the retina — the light-sensitive layer of tissue at the back of the eye. Photoreceptors cells in the retina turn the light into electrical signals. Those cells send the electrical signals to the optic nerve, and the optic nerve sends them to the brain. The brain turns those signals into the things you see.

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Sometime after dark the rattling of rain on our tent fly didn’t sound encouraging. The weather system had arrived even faster than forecast and, next morning we agreed that there was little point trying to climb treacherous, slippery rocks into viewless soaking clag. At least Brass Monkey Biv offered small scale shelter a few hours walking, over 1,643m Lucretia.

You want your glasses to give you the best vision possible. Adding anti-reflective coating to your lenses is one way you can optimize your vision.

The Biv is literally a two metre cube, with the top relenting into a small roof pitch (at two metres I might even be being generous). One side has a door, another a window.

Mt Apprentice track

The exact formula of anti-reflective coating depends on the company that makes it. In general, AR coating is made of many very thin layers of metal oxides that are applied to the lens surface. The layers alternate between high and low refractive indexes (the refractive index measures how the lens refracts — or bends — light). The more layers there are, the less amount of light that’s reflected onto the lenses of your anti-glare glasses.

Brass Monkey Biv

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At times the deer trails were quite apparent, but frequent, sodden, in-your-face tree branches made it difficult to see our feet. Eventually, after four or so hours of up and down we dropped a couple of hundred metres to the end of Duchess Stream and joined the Nina Valley Track. An old section of the track led us astray on the true left, chewing up another 45 minutes, so it was a pleasure to finally dump our dripping packs at Nina Hut.

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The back wall has two bunks, with the top bunk designed for contortionists. Though tiny, once we got settled inside, the interior did seem a bit larger than you’d expect it to be from the outside – a bit like Doctor Who’s Tardis in fact.

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AR coating is especially beneficial on high-index lenses. These lenses are thinner and lighter than regular plastic lenses. They can reflect up to 50% more light than regular plastic lenses so less light reaches your eyes.

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Anti-reflective coating has many benefits, but it is an add-on so your anti-glare glasses will cost more. If you’re considering it, talk to your eye doctor so they can help you decide if it’s worth it for you.

Most regular plastic lenses reflect about 8% of the light hitting the lenses so only 92% of available light enters the eyes. AR coating eliminates almost all reflections so up to 99% of light passes through your anti-glare glasses and reaches your eyes.

But before we headed down there to set up, we dropped our packs and scrambled up the Apprentice. The top commanded superb 360 degree views. Shaun rattled off many facts about the peaks, ridges and valleys surrounding us. The landscape stretched further out in every direction than I’d imagined. Regrettably though, clouds were gathering in the south west and the wind was building. This image - A view south and west from the summit of the Apprentice. Lucretia is directly ahead and the Grand Duchess (1,703m) slightly to the right. Our camp tarn is far left

After flying to Christchurch from Wellington, we picked up a rental car and drove up SH7 to a car park at 863m. From near the car park the Lewis Tops Track climbs rapidly up to nearly 1,600m – quick access to the tops, always good in my view. This image - At about 1,200m on the Lewis Tops Track, looking north to Mt Freyberg (1,817m - far left) and range, Cannibal Gorge centre and the Spenser Mountains, right