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How To: Calibrate your Maglite C/D focus system

ElectronGuru

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Aug 18, 2007
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Oregon
I stumbled into a solution to something that's bugged me for years. I haven't seen this before, so I thought I'd share. Note: this is for particularly patient perfectionists. All photos are 2007 Maglite 2C's.


Result
Perfect focus every time with maximum throw and no doughnut hole (using stock components)


click to enlarge

(view of bulb position with 10 o'clock calibration)​



Story
I was testing a pair of maglite's while working on an unrelated project, and noticed that they had different beam patterns, despite both heads being equally tight. I thought this was factory configured and having just taken them apart, assumed that I must have messed something up when putting them back together. But after swapping components and eliminating every other variable, it became clear that the starting point on the cam system is set more or less randomly every time the head is put together.


Background
The Maglite cam system works by pushing on the brass colored pin, shown here at 1 o'clock.

click to enlarge


As the tail of the blue reflector spins against the pin, it pushes down on it, forcing the spring loaded light bulb in and out of the reflector. This changes the elevation of the bulb, which in turn changes the beam pattern/focus of the light.


Problem
Most of the time, I want the light to be on maximum sharp focus. But this setting exists in only two narrow places on the cam. Finding them requires searching for the correct result, with little way to predict which way the bulb will go (up or down, more info below) with the next twist. Making matters worse, there's nothing to announce the magic point (from a UI standpoint) and you often must go back and forth several times to find it.


Goal
Calibrate the starting position of the cam inside the head, relative to the brass pin inside the body, making it easy to retain and repeat. For even more control, select which of the two ideal starting points gives you the better initial wide focus.


Technique
1a) install the lens and bulb you want to calibrate for
1b) changing the lens thickness or bulb height will move the sweet spot

2) ignoring focus, tighten everything down to the snugness (torque) you want to keep/repeat

click to enlarge


3a) the pin we are calibrating to is behind the switch, on the inside
3b) attach a post-it to indicate on the head where the switch (and pin) are on the body
3c) make sure the paper extends past the bottom of the head.

click to enlarge


4a) unscrew and remove the head from the tube
4b) remove the bezel, lens, and reflector
4c) with a metal tool, scratch a mark on the inside of the small end, relative to the post-it
4d) this is the [important] point where the head stops turning, relative to the pin

click to enlarge


5a) remove the post-it
5b) reassemble the entire head

click to enlarge


6a) loosen (don't remove) the bezel from the rest of the head
6b) inside, rotate the reflector to the desired position*
6c) tighten the bezel onto the head**

7a) put the head back on the tube and tighten with the same torque as step 2

8a) test for desired beam pattern
8b) if not right, remove the head and return to step 6a***
8c) take your time with this and when you're ready, move to step 9a

9a) mark the inside of the reflector with a sharpie so as to match the 4c mark
9b) marks on the bottom edge are quickly worn away by the brass pin
9c) if the tallest point on (apex of) the reflector is 12, my favorite setting is about 10 o'clock
9d) for the stock lens and 6D bulb I use, this starts at the tightest focus with full flood only a quarter-turn away.

click to enlarge


10) enjoy!

11) next time you remove the bezel, just line up the two marks, brace the reflector, and tighten

12) For multiple configurations or calibrations on the same light, use a different color sharpie for each


Notes
* Finding the desired position can take many on/offs of the head and loosenings/tightenings of the bezel. Keep in mind that there are two sweet spots, left or right of the apex. Left of apex means going downhill when first loosing the head, Right means going uphill. Down = bulb lower in the reflector, Up = bulb higher in the reflector. Since my sweet spot (10 o'clock) is already low in the reflector, I chose to go up rather than going the rest of the way down first.

** the import part when both loosening and tightening the bezel, is to brace the reflector from spinning (inside and relative to the head) with one hand while turning the bezel with the other. For example, put a finger inside the reflector's tube and bend your finger enough to brace against it.

*** in my testing, the reflector has more of a tendency to move (miscalibrate) when loosening the bezel than when tightening it.
 
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Dogbyte

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Jan 6, 2006
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Nova Scotia, Canada
Wow – thanks ElectronGuru. I have more Mag-Lites than I care to admit, and I find myself grapping a 4C with a Mag-LED most of the time mainly because it just happened to get assembled with the reflector in just the right spot that it's focused for maximum throw when the head is fully tightened. I didn't really know how to duplicate this until now – it makes perfect sense once you follow your instructions. Just finished 'fixing' my 2C with 18650s and a 5 cell Mag-num Star xenon, and my 6D with a Terralux LED. Time to round up the rest of the herd and fix the focus.

I love this forum! :thumbsup:
 

RickB

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Nov 10, 2006
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Seattle WA USA
Thanks for taking the time to write the detailed instructions and take and post the clear photos!

-Rick
 

Bushman5

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Sep 8, 2007
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after coffee break i'm going to go thru my maglites and try this, thank you for the clear instructions!
 

kosPap

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Mar 1, 2007
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Naoussa Greece
EG this is exactly how i have been doing for years...never hit me to make a post myself...

BUT I use carrection fluid for the markings...easily removable with a fingernail...

ALSO it should me mentioned that everytime the lamp is turned in the pedestal or everytime a bulb is replaced one should recalibrate...

All the best, Kostas
 

LuxLuthor

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Nov 5, 2005
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MS
Thanks for your post, but what does this do that cannot be done within a few seconds of rotating head while shining light at white wall? I'm not trying to be mean or overcritical, just maybe thinking I missed something.:thinking:
 

ElectronGuru

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Oregon
Hi Lux, its kind of a perfectionist thing.

In my years using full size Mags (started with MM's in the 80's), I've never liked the classic Mag ring of light and spent the time tuning the head before every use, as you describe. But fixing a tool before I can use it doesn't feel right to me. Its not about saving time, but avoiding aggravation. I want my Mags calibrated so I don't have to think about it anymore, where they just work the way I want, the first time, every time. I went so far a few years ago as to use LDF lenses, even at the expense of reduced output. But that also negates all focusability. Calibration gives the best of both.

I actually developed the technique, not working on my own issue, but someone else's. My nephew is in Army training and I built him a high powered (medium by CPF standards) 2C field light. As a portable spot light, its important that he be able to turn it on for only as long as absolutely necessary, to avoid being located himself. In this scenario, a light requiring tuning with each use is a tactical liability.

Does that help?
 

Burgess

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Apr 10, 2006
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Thank you for this info. :thumbsup:


Yes, i understand, it's a "perfectionist" thing. :)

_
 

wayne21

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Dec 15, 2008
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North Fl
Thank you for the information. I too like my lite to be as tight a spot as possable as soon as it is switched on. I just do not quite get the paper part, the rest I understand perfect. I will figure it out, Thank you.for sharing this with us.
 
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Benson

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Feb 15, 2009
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I've done a similar thing on my 2C Mag61, but it has a cammed metal reflector (FM, I believe) with the cam apparently longer than stock -- travel is limited not by the head threads, but by the slider bottoming out in its slot, so that the long side of the cam jams. What I did to calibrate it:
  1. Remove the bezel, reflector, and lens.
  2. Screw the (empty) head down fully.
  3. While holding the reflector fully in by hand, rotate it till you get the desired focus. (You may pulse it on intermittently to check the focus -- it's easy to overheat your fingers if you switch it on, then try to adjust the reflector!)
  4. Mark the reflector/head alignment (I just used a mechanical pencil, so I could remove the marks, but you could even use a scriber -- this'll be inside the bezel where it doesn't show.)
  5. Back the head off 1/4 turn or so.
  6. Align the reflector using the marks from step 4, and drop the lens and bezel on top of it.
  7. Holding firmly down on the lens to prevent lens (and thus reflector) rotation, screw the bezel on and tighten it. At the very end of tightening, the o-ring will grip the lens and rotate it, but the reflector will stay with the head.
  8. Clean the fingerprints you just left all over the lens. :D
If all went well, you can now rotate the head not quite a full turn, going from your calibrated focus (fully tightened), to bulb-out flood, back through spot to a slight bulb-in flood, where the cam jams the slider against the end of its slot. This is actually kind of nice, in a way -- the head simply can't come unscrewed, and you're never more than a turn away from your calibrated focus, no matter what. The downside is that bulb changes require removing or at least loosening the bezel, and loosing your calibration. (Or, I suppose, dropping the switch out the back...)
 

ElectronGuru

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Aug 18, 2007
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OMG yes. CPF is a bastion for perfectionists.

Most new threads fall into one of three categories:


What is the best (most perfect) x I can get for y [effort/money]

What is the best (most perfect) x y or z ever made or currently available

Why isn't x y or z good enough [for me]​
 
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eldons

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Jan 29, 2014
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ElectronGuru - thank you very much for this excellent set of Maglite procedures. You've helped me sol a problem that's bothered me for some time![
 
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