I really like the Tikka XP. I got the Princeton Tech Apex for the power. I wanted to see if it would allow me to leave my flashlight behind.

I actually prefer to have the Tikka XP plus flashlight combo better. More comfortable and versatile and actually smaller form factor for carrying.

Well, I have had the Tikka Xp for a couple of years now. And in spite of the manufacturer warning about lithium batteries, I have been using them. They went in automatically and I didn't even read the warning until I saw it in a forum. But it is still kicking and I haven't had to change batteries yet. And we camp about once a month plus I sometimes use it in the backyard and always have it in my backpack. I would estimate 25 to 40 nights a year of usage. That's good battery life.

After about a year of use, I saw the lithium warning. So I change it out to fresh alkalines. The old lithiums blew away the new alkalines so I switched them back.

Garmin wrote back and said that non-rechargeable Li batteries are safe to use in my eTrex Vista Cx.

Petzl wrote back saying that the REI numbers are very different than the numbers they got when testing the e+LITE at 70 degrees (they didn't mention whether or not they tested at 0 degrees) and they were looking in to it, and would email me back ASAP.

I have got a Petzl Tikka XP and a Zipka Plus, the former is nice and bright and the sliding difuser gives an even light. However it is slightly too big for my tastes to EDC due to the strap. The Zipka is not as powerful, but bright enough for everything I have needed to date and works pretty well to EDC in a coat pocket. As I understand it, while the outputs are not regulated, you can get a far more consistent output by using NiMHs.

My Tikka XP is actually an 'ATEX' version making it suitable for use in (most) potentially explosive environments, similar to the 'HazLoc' spec. Some may value this feature and I understand the e+Lite has this approval too with the advantage of lithium battery life. I was thinking of getting a couple of e+Lites for our cars but I am now keen to see the figures from Petzl for 0 degrees runtime first!

My ideal headtorch would be a Zipka version of the XP ATEX with a CREE or similar LED.

I received an email from Petzl with the following information regarding the discrepancy between REI's burn times and Petzl's:

Thanks Katie, and Petzl, for getting that discrepancy sorted out. I appreciate it.

Well, another thing learned today....

And now I understand why run times from manufacturers seem so exagerated....

For what it is worth, my e+Lite has given me significantly more burn-time then the REI site states. A new review of this light will be up on ETS in the near future.

Lumenence, or lumenousity, is a somewhat subjective standard I think. Before the advent of charge coupled devices and opto-electrical convertors, it was a lot moreso.

To get a true measurement of the total light output from a device, first you need a standard charge equivalent to compare to. Full moon brightness roughly equates to .25 lux, but it can vary. Establishing what .25 lux means is best down by converting some ambient light constant into an electrical charge that can then be precisely measured using available metering devices. Of course, any variation in color response of the sensors has to be considered, but generally this is easily done through prismatic isolation and measurement of specific wavelengths. So accounting for varying color dispersion, how does one equate flood lighting to spot lighting as a measurement of whole light output? There needs to be some means of ensuring a 100% coupling coefficient between the light source and the sensor, otherwise area dispersion variance would give a greatly unbalanced measurement of light generated.

What this means, then, is that for any given light source to be measured, either all of the light generated needs to be captured in order for the yield to be comparable between different sources, or some means of deriving an average value equivalent must be used. A light bulb's average luminousity per square meter at a given range will be less if the source transmits light in all three axes than if it is focused to some conical transmission plane. There are, of course, mathmatical solutions to compensate for such variances.

Then there is the question of which standard should be used, lux, lumens, or candlepower. I have yet to figure out how to convert one to another. I know this; when any of their values is zero, I can't see anything.

As a practical test, for spotlight sources, we have a stop sign that is about 600 yards out. If the light we are using throws enough downrange that we can see it's effect readily on the sign, then we figure it is bright, if we can't really tell any difference, then it is not so bright. If we hold the light in each others' face at night and we have to squint from the intensity, then we conclude it is bright close up, but not far away.

For flood lights, if we can read a book from the other side of the yard with it, then we say it is bright. If we have to get close enough that we can touch the light before we can read the book then it is not so bright, and if we can't read the book at all, then we say the light is broken.

As for how long the light stays bright, that is our cave test. We take a freshly charged flashlight and go as far in the cave as we can using that light till we can't see where we are going anymore. Then we know how long it will last us before we have to get out the handcrankers and find our way back out again. Another good test is to see if one of our buddies can field dress a hog at night without cutting himself. If he cuts himself, then we know the light ain't worth a dang.

LOL

I like your explanations at the end. They are written to where I can understand them