any reviews on the 14 LED Petzl Duo?

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any reviews on the 14 LED Petzl Duo?

Postby Trog » Nov 4, 2005 3:09 am

I'm consider getting that 14 LED array and reflector for the Duo on my Explorer.

Any reviews on this? is it easy to install?

how bright is it compared to a 14 LED speleo technics FX3?

Is it worth the money, bang for the brightness :) ?

will it fit older Duos? my helmet with the duo is a 1997 model
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Postby NZcaver » Nov 5, 2005 12:45 am

I don't actually have a 14 LED Duo, but I have an 8 LED and several 5 LEDs... :grin:

I'd be interested to know what people think of the 14 too. One was recently given to a friend of mine, as part of the Spelios helmet/light setup. We compared my 8 to his 14 in a cave, and the 14 is brighter - but not anywhere near twice as bright, as you might expect. It looks like it gives maybe 25-50% more light. I find the regular small LEDs without a decent reflector are only good for short to medium range anyway, compared to the 1 watt+ side-emitting LEDs that can be used for spotting. But the regular LEDs are still fine for walking passage, and the 8 is great for me. Maybe if you're in black lava tubes a lot, upgrading to the 14 might pay off. :wink:

I think the best thing about the 8 and 14 is being able to dim it. Stops you blinding yourself and others in crawling passages and when taking a break. The 5 LED can't be dimmed, but interestingly it's battery life far exceeds the others. It will last about 160 hours on 4 AAs, giving similar light to the medium setting on the 8 and 14. The LED inserts, by the way, are really easy to install - and they fit all vintages of Duo as far as I'm aware.

My conclusion - I'll stick with my 8 for now. I got the insert for about $30 a few years ago, when a store had one left on clearance.

FYI - I use the 8 on my regular helmet setup, with a Princeton Tec EOS 1 watt LED that runs on 3 AAAs as my spotting/backup light. My carbide setup, which gets little use, is an Aceto ceiling burner with a Duo 5 LED as the backup. 8)
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Postby potholer » Nov 9, 2005 8:10 am

The human eye isn't great at accurately comparing different levels of brightness - if a 14-LED did put out 2x the light of an 8-LED, it might well only seem to be 50% brighter or less.

The LED light I use has 3 power levels, with medium being 1/3 of full power, and low being 1/4 of medium. Subjectively, the difference between full and medium doesn't usually seem to be more than a 2x difference at best, and in some situations, if I closed my eyes for a few seconds when switching power, it'd be tricky for me to be sure whether I'd gone up, down or stayed the same. Between medium and low, the difference is more noticeable, but still doesn't look like a 4x difference in power most of the time.
Between low and high, especially on my spot beam, it looks nothing *like* a 12x difference, maybe 3-4x?.

Sometimes, where objects are dark, low contrast, distant or in a dimmer part of a beam, the subjective brigthness difference between levels may be greater, but often in those situations, the colours are muted on the lower of the two lighting settings, so it *may* be a special case of comparing a light level where the eye's colour receptors work properly with a level where they don't.
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Postby NZcaver » Nov 9, 2005 6:10 pm

Potholer - you make a valid point.

Unfortunately, I don't have a light meter to accurately test headlamps and prove or disprove my assumptions. Generally, if any given light appears brighter (or dimmer) to me in a cave - it doesn't really matter if it's "technically" brighter or not! Like the cliche, it's all in the eye of the beholder. :wink:

Once you know how much light you want in your caving environment, the tech specs give more help in working out the best way to get optimum battery life - and how to get the best value for money when purchasing a new light.

I'd be interested to know what type of light you use... :grin:
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Postby potholer » Nov 24, 2005 6:24 pm

Apologies for not replying earlier - I didn't seem to get an email notification.

I'm using a self-built light, but since I am actually selling some (though only in the UK, and all but a handful of them to acquaintances), I'm wary of saying too much here for fear of seeming to advertise.

Basically, it's a twin-beam conversion for a mining headset, with a narrow spot beam (with some downthrow) and a very wide beam (with limited punch at distance). Neither beam really compares directly to a 14-LED setup, since the spreads are so different.

It's not in the same league as the brightest LED lights when it comes to big-chamber lighting and total output, (I don't think Stenlight have anything to fear), but as an expedition-targetted light, extended runtime was overridingly important, and that, plus simplified electronics and heat issues, pushed me to a maximum of 1W/beam, which still seems enough for both close-up and distant work, and often I run somewhat dimmer even when I'm not worried about battery life.

There are are a few times when more light would be nice, but then it's not clear how *much* more light would be needed to make a real difference to the worst-case locations.
Uneven muddy floors definitely need some spot beam in the lighting mix - a very even spread-light makes little impact on them, even close-up, but adding just a low spot can make a serious difference.

Fortunately, value for money isn't something I have to worry about, as long as I mentally write off development time as a learning experience.
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