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Discussion Starter · #1 ·
Hi all,
This may sound like a very stupid question but i'd feel even worse if I didnt ask it and was wrong so here goes.
Are the outputs of LED and xenon torches comparable i.e. if a xenon torch states 115 lumens (princeton tec surge 7.5watts) is that almost twice as bright as the tektite expedition star LED stating 65 lumens?

I know that the wattage outputs cannot be directly compared and I am now just getting confused.

Also which would people recommend for penetration? LED or xenon?

Thanks.
Nick
 

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Irish Cave Diver in the making
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This may sound like a very stupid question but i'd feel even worse if I didnt ask it and was wrong so here goes.
I sort of asked it a while ago too.


Are the outputs of LED and xenon torches comparable
Apparently not. The only real comparisons you can make on paper with lumens, is if the same manufacturer compares two or more of it's own torches - silly isn't it? But I suppose that is why we get dive magazines from time to time doing their own comparisons using a light meter thingy and also showing you the spread and pattern of the beam.


I know that the wattage outputs cannot be directly compared and I am now just getting confused.
Halogen to halogen can, Xenon to xenon can as far as I am aware. But Halogen to xenon can't - xenon is apparently brighter than halogen for the same wattage. And of course a 10w HID is brighter than a 10W Halogen or Xenon.

Also which would people recommend for penetration? LED or xenon?
For penetration, in my opinion it is LED. Some people say that Halogen or xenon is brighter that LED in lighter conditions (with ambient light) and that LEDs need it to be dark to be effective. But i 'think' that this is more an illusion than fact. In 'my opinion', the white light of LED is not noticed as much as the yellow light of a similar brightness, of the other two. But the difference is that one colours the subject yellow, and the other doesn't. Though that doesn't mean that the LED isn't any good in lighter conditions. But, if you normally dive in shallower waters where ambient light gets through, you may feel better with a xenon over LED as it seems brighter.

Now, that makes it all easier to understand and compare doesn't it :D

If you have an idea of a few torches, post them up as some people may have experience of more than one of them so can compare and can help you choose.

I hope I have illuminated these matters for you :D
.
 

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Jonah
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For penetration, in my opinion it is LED..
I actually think LED lights have poorer penetration, mainly due to the difficulties in focusing the beam (usually because multiple LEDs are being used).


I agree with your comments about the colour of the light etc, but that's a slightly different issue.
 

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Its pretty much impossible to compare lights on paper. Even comparing halogen to halogen or LED to LED is difficult, because how well it works depends as much on the beam as the power of the light. Even those that claim to have the same beam angle can be rather different from torch to torch.

Use power and beam width as a vague guide to work out which torches to look at, but its worth getting some subjective comparisons of those you're considering before making the final decision.

David
 

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Discussion Starter · #5 ·
Thanks for clearing that up. It seems that buying the right backup torch can be very difficult on paper and as you have all suggested it may be best to try and get some subjective opinions.

The torches I was considering were either the princeton tec surge (£30) 7.5watt xenon (or the salvo version for the same price)

or the tektite expedition star LED at £49.

I know that this has been done before on various threads so please bear with me.
Does anyone have any views between the two?
I have a very limited budget but am open to a little pursasion if anybody wants to try.

Thanks for all the replies so far

Nick
 

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(Formerly Polarbears Dave) - YD advertiser
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For a back up I would not consider anything using an external switch (eg Princeton Tec Surge), as it is an extra leak and failure point
By far the most important consideration for a back up is reliability
cheers
dave
drysuitrepair.co.uk
 

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Irish Cave Diver in the making
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I have the Salvo. It is a very good torch for the money and would be happy to recommend 'as a back-up' - lots of light for the price. The reason I would suggest as a back-up and not as a main torch is the battery life - it uses batteries at a shocking rate.

I believe the Tektite has gotten some very positive comments on here.
 

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For a back up I would not consider anything using an external switch (eg Princeton Tec Surge), as it is an extra leak and failure point
By far the most important consideration for a back up is reliability
cheers
dave
drysuitrepair.co.uk
It's true that having a switch through a housing is an extra leak point, but having to partially assemble your torch underwater to turn it on (screwing the head down) is much more of a leak hazard than a properly designed switch.
 

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For a backup I have a UK Mini Q40 eLED (about £30). It is solid, simple and very bright although quite a tight spot beam (20 degrees they say - whatever that means).

Certainly good enough for the rest of the dive if my Greenforce HID packs in.
 

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It's true that having a switch through a housing is an extra leak point, but having to partially assemble your torch underwater to turn it on (screwing the head down) is much more of a leak hazard than a properly designed switch.
I'd disagree with this. The switch usually has a number of potential failure points such as the shroud, the seal and the switch itself. The screwdown method only has the O-ring(s) as a potential failure point.
 

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I have had a Princeton Tec Surge for about a year. Never used it on a night dive but it made a good fist of illuminating the interior of the Stanegarth and the Thistlegorm by day. I bought it as a primary until I can afford a "light sabre" in which case it will become my backup. It takes AA batteries which you can get anywhere and you get ages out of a set of Duracells. I think it's a great torch for the money.
 

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All hail the mighty ZOM
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I'd have an Expedition Star out of that lot. Here's a photo of a 5.5W SL4 (left) next to an Expedition Star (middle) with a 14W 8 D cell lantern on the right:



The big difference in burn time- you get 25 hours from an Expedition Star and about 2 from an SL4 if you are lucky.
 

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Discussion Starter · #13 ·
thanks for all the replies so far.
I am tempted with the tektite...especially after seeing it in action in woz's picture. still somewhat undecided though especially with all the replies recommending the 7.5watt (and the negatives abou it).

I'm going to do some thinking and try and get hold of one to try I think before I shell out the cash.
Thanks again everyone
 

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I also use an Expedition Star & have been very impressed with it both as a backup and holiday torch.
My only issue with it is that the rubber guard keeps falling off which eventually meant I lost it but I have replaced it with a snug fitting piece of innertube but Wally has promised to get me another one.
 

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All hail the mighty ZOM
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I also use an Expedition Star & have been very impressed with it both as a backup and holiday torch.
My only issue with it is that the rubber guard keeps falling off which eventually meant I lost it but I have replaced it with a snug fitting piece of innertube but Wally has promised to get me another one.
Either superglue it on or chuck it away and use some black tape on it.
 

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Silent Knight
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...or before you lose it some fabric tape underneath (like in hose repair kits)

Got to agree with choosing the Tektite Expedition Stars though. I took advice from searches on here for a backup torch for Nic and I and we both think they're great. Rob Lumb ( Lumb Bros Greenforce Distributors in the UK ) sorted them out for us super quick - great people to deal with. Sensible money for a back-up too I felt.

Cheers

Graham :)

.
 

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Just to really screw your head up..................from Wikipedia....

The lumen (symbol: lm) is the SI unit of luminous flux, a measure of the perceived power of light. Luminous flux differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light.

The candela (symbol: cd) is the SI base unit of luminous intensity (that is, power emitted by a light source in a particular direction, with wavelengths weighted by the luminosity function, a standardized model of the sensitivity of the human eye).


In other, more understandable words, Lumens is roughly "light per unit area of focused spot" and candella is total amount of light given out, regardless of focus. Lumens and beam angle are what you need to compare, even then its dodgy, because of different light temperatures (how yellow/white/blue it is).

Personally, I made an insert for my UKD4R, which has 25 x 1000 mcd LED's in, which focus to a 2' diameter spot at about 6' distance. Its nearly as bright as the 18w Xenon bulb (which is still in there also), but lasts about 25 times longer. It took about 4 hours to make, and cost under £10.

Phil
 
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