J2Ski Forum Posts and Replies by ise

AllyG wrote:I phoned my optician, and he said both my reactolite (actually I think they're called transitions) and my sunglasses are both uv 400. But he also said my vari-focal transitions only block out 80% of the visible light at maximum, and the sunglasses only block out 85% of visible light.

Plus, my sunglasses are wrap around, but my transitions are like ordinary glasses.

Ally

More importantly though, what was his expert opinion? Did he reckon that they were good enough?

You've mentioned another good point as well, the shape of glasses, it doesn't matter how much light the lens blocks if it's all just coming round the side anyway.

AllyG wrote:

ise wrote:. To avoid ultraviolet keratitis you need glasses that block all UV light and about 90% of visible light.

Thanks for that Ise, :D and nice to see you back. I had no idea that sunglasses for ski-ing blocked out so much of the visible light. It's amazing we can all see where we're going when we're wearing them!

I generally wear my ordinary reactolite prescription glasses, but I also have prescription dark glasses for ski-ing. I have no idea if they block out enough light to prevent me getting eye damage. Maybe I should check with my optician. I just assumed they'd be okay because I told him I was going to use them for ski-ing.

Ally

As I understand it then it's a little confusing, when you think of blocking visible light you immediately think of something like turning the lights down and that's not really what we're after. What we're after is something more like clipping out some higher frequencies. It's actually this reduction in light in the normally visible spectrum, i.e. frequencies lower than 400nm, that's important for preventing snowblindness. The right tint on any glasses, regardless of their type, together with UV protection is all you need. An expert can slice and dice those EN172 and EN170 scales and work out if any given pair of glasses is any good, the specific three pairs mentioned above don't appear to filter out enough light to me but you'd need to ask an optician to be 100% sure, I think EN172 and EN170 both define some altitude measures although it's a specialized area and a lot of the standards are over my head. Asking an optician or using models developed for this specific environment is better.

That's not to say some sunglasses are a bit overpriced, I don't use Oakleys personally as they look a bit dear, I do use Bollé, Cebe and Alpina with Bollé probably being my optic of choice at extreme altitude. They're not too expensive and a concern over breaking or loosing them is a bit of a red herring, I don't carry anything I don't actually need at extreme altitude so I can't afford to lose my glasses whether they cost me 10 quid or a 100 quid.

I would imagine reactolite glasses are fine, personally I'd not choose to wear them personally, I'm still dubious that they really react quick enough despite recent advances and I don't believe they're really effective at very high or extreme altitude in purely visual terms where I think the weighting of light to the higher frequencies would make them too dark to be useful at times. But that's a personal choice about vision based on my opinion not something based on any information about them not being safe.

Ian Wickham wrote:I'm looking to buy Mrs W a new pair of sun bins for xmas, I think I might go for trenchers safety option :lol:

If you're buying sunglasses to use in snow and the mountains you probably want to look for glasses labelled as protecting "UV400", that means that they will block light at wavelengths shorter than 400nm. Some manufacturers define UVA starting at 380nm which is why claims of 100% UV protection need treating with some caution and why manufacturers are able to reasonably claim UV protection exceeding 100%.

Glasses made specifically for the mountains will also block light at the higher frequencies of the visible spectrum, that, along with the gap between 380nm and 400nm, is pretty important as it's the critical frequency range causing the condition ultraviolet keratitis more commonly known as snow blindness. To avoid ultraviolet keratitis you need glasses that block all UV light and about 90% of visible light. The standards EN172 and EN170 define testing and classification of lenses for UV protection and light transmission so using those scale numbers you can see the particular safety glasses mentioned previously do not appear to offer adequate protection for use in polar, snow or high altitude environments.

UV is more pronounced in polar regions or with altitude, as a rule of thumb UV intensity increases by around 13% for every 1000m gain in height, if you happen to ski around sea level in a non-polar region it's not a huge deal but personally it's something I would be concerned about, I live at high altitude and work at very high altitude / extreme altitude so I would personally prefer to use optics designed for that application, age is damaging enough to eyesight without exacerbating it.

Contact lens wearers may not know that it's possible to use lenses that provide protection in their own right, it's not a substitute for real glasses of course but the Accuvue's I wear nowadays offer 82% UVA and 97% UVB blocking, that's enough for short periods of exposure without other optics.

A few snaps from a ski area I've not been before. I've skied the top of the Aletsch Glacier a few times from the Jungfraujoch but we've turned off to climb other peaks. The Aletsch glacier is the largest in Europe at 23km in length and 120 square km, the glacier itself is a UNESCO World Heritage site.

It was actually a pretty nice day in Zinal when we left, so it's a credit to our grit, determination and planning we were able to locate an isolated pocket of poor weather and clouds.



Looking back homewards you get a good view of the Matterhorn.



It's a pretty good ski area and quite extensive really, a fair amount of it was open today as well and they were doing a 20.-chf ticket deal which is what had drawn us there.








Looking down on the Aletsch Glacier.

clubman wrote:

ise wrote:..... the second problem is more serious though, the visibility is so poor that some micro-navigation is needed to avoid the two large crevasses near the top of the glacier, so for a short section we're all in a line picking our way through....

Just spotted this thread. Care to enlarge a little on the above? Were you familiar with the glacier and where the crevasses were at the time?

only just seen your reply, I've been away a while ) The main glacier complex is fairly accurately marked on the map there and several of the group had routes/tracks on GPS and/or annotations on local maps. Half a dozen local/localish guides/IML's/accompagnateurs/aspirants etc helps when you're trying to avoid falling in a hole though.

scapula wrote:What to do if you`re infcted....well some information here including the ip`s to block if you know how do do this....http://facebook.of-cour.se/

I don't think as individuals blocking IP addresses is a very good idea, not only is it going to be something a lot of people can't do it's also ineffective as these addresses roll over pretty quick.

Making sure the URL in the address bar looks like the site you think you're accessing is a better idea. Asking yourself why you're being prompted for a login, if it's what you expected to happen or not. Having different passwords for services like Facebook or MySpace and then not storing data on there that doesn't need to be there etc are all better ideas.

Not installing applications into facebook that you don't need may be the best idea of all and not spamming your facebook friends with invitations would be nice as well :D

bandit wrote:

ise wrote:

Tony_H wrote:7 out of the top 10 in Austria, Mr Wickham. Interesting.

I wouldn't read too much into that, they are German, it would be surprising if they didn't have more coverage in German speaking areas and have a preference for the stations closer by like sud Tirol.

It's a bit like a UK survey turning up the Val d'Isere and the Portes du Soleil are the top, it's a bit of a self fulfilling prophecy.

You are alleging bias, shirley not :shock:

I reckon the skiing public is a bit smarter these days, so it's logical that a report with a pre-determined outcome, will only be of interest to it's target audience, because it was written with that sole intention.
Independent thinkers do their own research.

It's not really bias in a bad way, their audience is German so if they produced a list of great stations in the rockies it wouldn't be a lot of use to their readership. I've still got a couple of German atlases of ski stations from when we lived there, really well written and researched.

What you can be sure of though is this survey will be more accurate than anything produced in the UK, the UK ski guides are so comically bad as to be useless. Reviews are written by people who show no sign of visiting the place they review, or no sign of having been anywhere else, or got it all on a freebie :roll: The Bodo-Kachari (a Tibeto-Burman hill tribe) guide to European Ski Resorts (print run of 1, written on bark, published 26 BC and not available on Amazon) is dramatically more accurate than anything in the UK.

still interesting though, this sort of list probably throws up places people in the UK wouldn't hear of otherwise.

It's just all of these surveys and reviews are useless if you take them too literally.