Cheers Skids. To be honest I think removing the barrel that is in at the moment would be a heck of a job. Think I'll go down the Blue Peter route and get out the trusty old velcro pads
Cheers Skids. To be honest I think removing the barrel that is in at the moment would be a heck of a job. Think I'll go down the Blue Peter route and get out the trusty old velcro pads
Be Humble. Sit Down.
simon, you might have a bit of a duff one as you said earlier. I have had my torch for about a month andthe barrel is doing the job it's supposed to do with no slippage of the main unit up or down hill, fast or slow pace.
I don't think that's quite true... Lumens ought to be a simple measure of the light output (illuminance). Once you take the beam spread into account you are into measuring Lux... (I think).Originally Posted by Gravymuncher
eg 1000 Lumens falling on a surface 1m square = 1000 Lux but 1000 Lumens falling on a surface 10m square is only 100 Lux.
I think the point you are making is that the more you spread the beam the less bright it will seem (ie less Lux), but surely 900 Lumens is 900 Lumens, unless I've misunderstood the theory somewhere.
I have a Lux meter so I may do a few tests with my current headtorches. Under strictly controlled scientific conditions of course
In the cupboard under the stairs, with a half-flat battery and after a couple of beers is my usual set of strictly controlled scientific conditions
I have a Lux meter so I may do a few tests with my current headtorches. Under strictly controlled scientific conditions of course
Boo still not picked it up I have seen one of my team mates though and it's bright, very bright! Also i was amazed how small and light it was, maybe half that of the Myo XP yet with twice the lumens! He's had no problem with the tilt and I put it on and jumped around and it stayed put.
looks brill can't wait till Monday......Again.
I've sorted mine. Velcro pads superglued into the space between the lamp and its housing, with a double sided pad to stick in inbetween if I need to adjust the angle. Something else to remember to stick in the bumbag!
What a bloody faff!
Still reasonably chuffed, its a very bright light and its opened up some more hardcore running in the dark.
Be Humble. Sit Down.
You can easaly measure the Lux with your lux meter. Mesureing the Lumens is far harder, done properly you use an Integrating shere. You could have a go at guestimating by taking lots of lux readings to see the falloff and then doing a load of maths. For comparison of lights you phisicaly have where most of the light gose basicaly forward then a cieling bounce test works fairly well. Point the light and your lux meter at the center of the cieling and take a reading repeat for your different lights. Just need a good white matt finished cieling.
I was even less scientific than that… I just went out into the garage (which is fairly pitch black), put the Lux meter on the floor, stood about a meter back from it with each headtorch on and shone the lamp at the meter. I had the meter set to record the max level and reset it after each test. I did 5 tests on each lamp and roughly averaged them.
The only lamps I had available were a Petzl Tikka XP, my trusty 14LED Petzl Duo (with halogen bulb replaced by a 0.5w Luxeon LED), and my big Silva 480 halogen orienteering lamp. I would have liked to have included the Petzl Myo XP (2008) but my girlfriend has borrowed it….
All the lamps were on fully charged NiMH rechargeable batteries.
Results:
Silva 480 (20w setting) – 950-960 Lux
Silva 480 (10w setting) – 650-700 Lux
Petzl Duo (14LED) – 390-420 Lux
Petzl Duo (Luxeon 0.5w) – 180-200 Lux
Petzl Tikka XP – 200-230 Lux
Petzl Tikka XP (with diffuser in place) … 70-100 Lux (!)
It’s actually not even necessary to be as scientific as this because the subjective perceived light is the only thing that matters really. This test threw up no surprises at all – if I’d guessed beforehand I wouldn’t have been far off.
The Silva halogen gives a yellower light but it gives a LOT of light. Pity the battery life is so pathetic! The Tikka’s diffuser robs the lamp of far too much light (same with the Myo). The Duo (on 14LED setting) gives a nice flood and is actually pretty bright, though some people think it’s too heavy. It’s still my favourite all-rounder.
A broad beam (flood) is crucial for fellrunning I reckon and the Duo and the Silva both provide that. A narrow pencil beam is definitely NOT what you need, however impressive the maker’s beam length figures are.
You have just measured the max brightness of the spot. I could sugest some lights with very narrow beams (a £10 offering from tescos comes to mind) that would blow those numbers away but they are not at all good for running with because of the very narrow beam. As you say you need a good spread as well as some throw for running. The diffuser on your Petzel has robed you of some light but the main reason for differance is that it has of course spread the light out thus reducing the intensity of the spot.
Found this about the LED Lenser.
http://www.ukclimbing.com/forums/t.php?t=429833
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