Torch question

j.w. · December 7th, 2005, 01:02 AM

Why does your torch need to be focusable to signal with it?
Cheers John.

*Brian Allen* · December 7th, 2005, 01:05 AM

It needs to have a very bright central spot so that the power is focused into a single area so that it penetrates really well and produces definable signals.

I think... well that's what my focusable lamp does.

j.w. · December 7th, 2005, 01:57 AM

Quote: (Originally Posted by Brian A)

It needs to have a very bright central spot so that the power is focused into a single area so that it penetrates really well and produces definable signals.

I think... well that's what my focusable lamp does.

So is the requirement just a powerful torch with a spot type beam angle? As opposed to a torch that you can adjust.
Cheers John.

Rob Dobson · December 7th, 2005, 10:40 AM

Quote: (Originally Posted by j.w.)

So is the requirement just a powerful torch with a spot type beam angle? As opposed to a torch that you can adjust.
Cheers John.

Long enough burn time to conduct a given dive and with a focused beam. Ideally with the battery in a cannister and the light head on the end of an umbilical cord.

Adjustable focus might be useful in theory but in practice I've only ever wanted my beam to be as tight as possible so your team can track you and signals are more defined. Trying to signal with a wide-beam torch just doesn't work.

There are a number of DIR torches out there with fixed focus spot beams. These are fine. Good lights as far as I know.

HTH

Joe Hesketh · December 7th, 2005, 11:37 AM

Quote: (Originally Posted by Rob Dobson)

Adjustable focus might be useful in theory but in practice I've only ever wanted my beam to be as tight as possible so your team can track you and signals are more defined.

Having the ability to adjust the beam is useful - what you're really doing is adjusting the distance from the reflector to the point where the beam converges into a nice clear bright spot. That distance will vary depending on a number of factors such as how clear the water is and how far away the object or surface on which you want to signal is. It's not that you need to continually adjust this, but for example, signalling on a cave wall in a large passage with crystal viz is going to require you to ‘focus’ over a longer distance than signalling in crap viz on a wreck as, if left at the same setting as the first example, your light wouldn’t penetrate to the distance at which it’s focused.

Hope that makes sense.

Quote:

There are a number of DIR torches out there with fixed focus spot beams. These are fine. Good lights as far as I know.

They are, but note that they generally have tighter beams than other “spot focus” lights. E.g. the Halcyon has a 6 degree beam compared to around 10 degrees for the tightest model on some other popular designs.

Divingniknaks · December 7th, 2005, 02:25 PM

The Salvo fixed focus is a 12 deg light, and is a perfectly good signalling and general purpose light.

HTH

December 7th, 2005, 01:02 AM	#1 (permalink)
j.w.(Offline) New Member Join Date: Nov 2005 Location: Essex Posts: 12	Torch question Why does your torch need to be focusable to signal with it? Cheers John.

December 7th, 2005, 02:25 PM	#6 (permalink)
Divingniknaks(Offline) Resident purveyor of shiney kit.... Join Date: Nov 2005 Location: Midlands UK Posts: 1,038	The Salvo fixed focus is a 12 deg light, and is a perfectly good signalling and general purpose light. HTH __________________ Phill ----------------------------- Salvo Lights, DirZone Gear , Frog Wings Dive ? http://www.divingniknaks.com

December 7th, 2005, 01:05 AM	#2 (permalink)
Brian Allen(Offline) GUE Instructor Join Date: Nov 2005 Location: London & Plymouth Posts: 593	It needs to have a very bright central spot so that the power is focused into a single area so that it penetrates really well and produces definable signals. I think... well that's what my focusable lamp does.

December 7th, 2005, 01:57 AM	#3 (permalink)
j.w.(Offline) New Member Join Date: Nov 2005 Location: Essex Posts: 12	Quote: (Originally Posted by Brian A) It needs to have a very bright central spot so that the power is focused into a single area so that it penetrates really well and produces definable signals. I think... well that's what my focusable lamp does. So is the requirement just a powerful torch with a spot type beam angle? As opposed to a torch that you can adjust. Cheers John.

December 7th, 2005, 10:40 AM	#4 (permalink)
Rob Dobson (Online) Chillin' with the ninjas Join Date: Nov 2005 Location: Oxford Posts: 536	Quote: (Originally Posted by j.w.) So is the requirement just a powerful torch with a spot type beam angle? As opposed to a torch that you can adjust. Cheers John. Long enough burn time to conduct a given dive and with a focused beam. Ideally with the battery in a cannister and the light head on the end of an umbilical cord. Adjustable focus might be useful in theory but in practice I've only ever wanted my beam to be as tight as possible so your team can track you and signals are more defined. Trying to signal with a wide-beam torch just doesn't work. There are a number of DIR torches out there with fixed focus spot beams. These are fine. Good lights as far as I know. HTH

December 7th, 2005, 11:37 AM	#5 (permalink)
Joe Hesketh(Offline) New Member Join Date: Nov 2005 Location: London, UK Posts: 657	Quote: (Originally Posted by Rob Dobson) Adjustable focus might be useful in theory but in practice I've only ever wanted my beam to be as tight as possible so your team can track you and signals are more defined. Having the ability to adjust the beam is useful - what you're really doing is adjusting the distance from the reflector to the point where the beam converges into a nice clear bright spot. That distance will vary depending on a number of factors such as how clear the water is and how far away the object or surface on which you want to signal is. It's not that you need to continually adjust this, but for example, signalling on a cave wall in a large passage with crystal viz is going to require you to ‘focus’ over a longer distance than signalling in crap viz on a wreck as, if left at the same setting as the first example, your light wouldn’t penetrate to the distance at which it’s focused. Hope that makes sense. Quote: There are a number of DIR torches out there with fixed focus spot beams. These are fine. Good lights as far as I know. They are, but note that they generally have tighter beams than other “spot focus” lights. E.g. the Halcyon has a 6 degree beam compared to around 10 degrees for the tightest model on some other popular designs.