wanted head lamp

[John Nicholson]

I did not realise how much I grunted and snorted until I downloaded and played the films I took.  The microphone picks up everything.  I now understand why Ian cuts out the cave noises in most of his films, and dubs in his familiar choice of music.

Is there a direct relationship between watts and lumens?

[mike leahy]

yes . tim is the biggest lumen i know. sorry john i thought you said lemon :whistle: :whistle: :whistle:

[John Nicholson]

Dear Mike!
What are you drinking this evening!
I meant it seriously......  

5 watts = how many lumens?

[Danny Sutton]

[quote="JohnNicholson" post=7427]Dear Mike!
What are you drinking this evening!
I meant it seriously......  

5 watts = how many lumens?[/quote]

it doesn't, a watt is a measure of energy, a lumen is the amount of light visable to the human eye.

[Ali Wiseman]

I am, and I must emphasise this bit, SLOWLY, attempting to make a Driver with "Autodim".

The idea is a blatant rip-off of the Petzl Nao, which dims when it detects a light shining on it, which usually means you are talking to someone with a light on their head too.

Hopefully this means You can have a Batburner of a light (Needed for Filming), and yet keep the Dazzle to a Minimum (and as a nice bonus, extend the runtime of the lamp).

Don't hold your breath, it's not something that will happen fast.

[John Nicholson]

Sounds like a brilliant idea.

[Tim Watts]

John,

impossible to directly compare watts to lumens. In fact, believe it or not its hard enough to compare lumens to lumens!

So much is dependant on optics, i.e. x amount of light focused/spread in what pattern. And then what specific wavelength is the light spectrum, and how the human eye (and eveyone is different) responds to the wavelength spectrum etc etc.

In 'real' terms the £30 job i posted is a fairly bright lamp compared to little crappy elastic petzl type things, but nothing like the trigon on full power - best thing i can suggest is that i'll bring it underground with me and you can try it for a day - you still going on the 8th???

[Ian A]

John,

Your ability to pick up on light underground is not just down to your lamp but also your choice of video camera. I have been through lots of failed video cameras to find one that picks up well in low light. It is for this reason I have bought more than 20 of the same camera - because it works well in poor light.

If you are relying on light then you need 500+lumens for a small lead mine type passage and 2000+ for a slate cavern and they are minimum levels



Ian

[John Nicholson]

Thanks Ian and Tim.
It would be great to try your big light underground if we can come on 8th.  Also it would be good to have a 'camera compare' session with you Ian.  There are lots of features on our new camera that I have not tried yet, and as with most things I learn slowly.  The camera we now have (Coolpix 3300) is supposed to be a lot better than the one we had so many problems with. It does seem easier to swap between stills and movie.

The reason why I was asking about lumens and watts is to compare the specifications of lights, some of which are given as watts and some as lumens.

[John Oh]

This is a bargain back up light, not tried under ground yet as my son borrowed it, but very bright for the price

http://www.ebay.co.uk/itm/260970462254

I also go one of these which is even brighter, but still not tested it as Ian couldn't find the mine :ohmy:

http://www.ebay.co.uk/itm/200727269390

Unless you want a very specialised lamp, I don't think there is any point in trying to make your any more.