Sorry not a mod anymore but I'll report it so someone will eventually move it.
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I am only 5'9" and even a long light like the 500 Lumen DR is not an issue.
There are short 2 cell options like the mini-scout that save a couple inches over the normal 3 C cell lights, but generally you lose either brightness or burn time - there is after all no free ride.
I recently tried the Princton Tec Torrent LED. Lots of light for its size and great burn time. It runs off 8 AA batteries so it is amost in the same lenght class as a 2 "C" battery light and is about 6 3/4" long compared to the 8" or so of a 3 "C" light. It is also well designed in terms of having two o-rings and a solid yet non snagging place to tie a bolt snap on the end.
Like most LED's it is not quite as tightly focused as most halogen lights, but it puts out a lot more light and the quality of the light is much better - blueish white as opposed to yellow. Some divers regard tight focus as being important in a back up light for signalling purposes. But for reliability you have to under volt a halogen bulb so you end up with a tightly focused but very dim light for a given battery capacity.
Personally, I don't think tight focus matters as my buddy is gonna notice the much lower output of my backup either way unless she is asleep. After that the guy with the failed primary normally leads out, or at least does stay in the tail ned position. So I tend to go for the brightest LED I can find in a given size back up light as I have found that more useable light helps more in a backup than just a tightly focused beam. More importantly the latest LED's even if not as tightly focused will have a brighter center spot and a 2 or 3 cell Halogen light anyway so it is pretty much a moot issue anymore. The high reliability of LEDs has pretty much eliminated the need for a highly reliable and undervolted Halogen back up light. And there is a lot to be said for a backup with a 20 hour burn time compared to maybe 60-90 minutes. You can get mini scouts etc, but again there is a cost in terms of burn time and out put.
Nothing against the normal cave diving equipment companies, but they get their LED internals from Princeton Tec or other light companies, which pretty much ensures they are a generation or so behind with less light, less focus and about twice the cost per lumen.
For example the Torrent LED will sell for $70 - less than half the price of comparable Salvo or Halcyon LED back up light.
The thing I do not like about the Torrent LED is the switch as it can come on by itself, unless you are careful in how you stow it. On the other hand it does not twist on or off so you will not accidentally unscrew it too far and flood it and with the burn time, even being on the entire dive would not place you at risk of it burning out.
My "primary" backup light used to be a 500 Lumen DR hand held, but quite frankly the Torrent LED leaves it in the dust in terms of output and it costs $70 to the DR's $300. (A year or so makes a huge difference in LED technology and price) The saving grace of the DR is that you can get it with a cord option and in that regard it can stand in for a primary, but it has already become old tech.
Below is:
1. The DR 500 Lumen handheld (old tech)
2. Pelican Sabre light (really old tech)
3. The Princton Tec Torrent LED
