What's the history and origin of the Surefire SRTH?

Proud SRTH owner here.. but I also realize I know very little about it.

Some places tell me it originated from the 12ZM light, but I was under the impression the 12ZM came with a 3" T-series Turbohead and not the SRTH.

Any information on the SRTH is appreciated especially about its history, lights that it was intended to be mounted on, and so on.

The "history" of TurboHeads is not that clear to me (not as clear as I'd like and I've spent quite some time trying to find out). I wasn't there at the time when these TurboHeads were released. However, this is my take on it:

Here are four different TurboHeads and the names used to describe them:


First, there was the "T" Extended Range TurboHead. 3" diameter. There are at least two main versions: One with a 'flat rim' like the T3 in this photo:

And one with a stepped rim like the other two TurboHeads.

Next, came the SureFire 12PM/12ZM. This "Tactial Entry Light" was 'compact' compared to the "T" Series TurboHeads because it's TurboHead was only 2.5" diameter.
Now most of the photos you'll see of the 12PM/12ZM feature what I consider to be the "standard" TurboHead for the 12PM/12ZM. It has an extended rim that is threaded on the inside so that it could accept an IR BeamFilter.
BTW, this BeamFilter was never released to the public and I used to have a photo of it - the only one I'm aware of but I lost it when my last PC died. Anyway, the 12PM/12ZM TurboHead bezel and N62 lamp was a kit called the "T62". I've never seen a photo of the T62 but I assume it is the TurboHead with the extended rim.

My understanding of the SRTH is that it is a "Short Rim" version of the T62. It was made because there was no need for the extended rim since the BeamFilter(s) for it were never released. Additionally, the reflector finish of the SRTH is different to the T62. The T62 was designed for the N62 lamp. The SRTH has a reflector finish like the "T" TurboHead. That's my experience based on the ones I've got. SureFire are known for experimenting. Early "T" TurboHeads had reflector finishes that were pretty much "mirror" without any stochastic "ripples" or "dimples".
The SRTH is designed and intended for the N1 and N2 lamps assemblies. It's fine reflector finish can fail to blur the larger filaments of the "MN" type Lamp Assemblies resulting in a poor quality beam.
This fine finish results in a tighter, more intense beam though so it does have good advantages with the right lamp assemblies.



The only place to purchase an SRTH is SureFire Dealer Lagger Pro (aka LPS).
It is possible that LPS requested that the SRTH be created, or, I guess more likely did a deal with SureFire to buy all the SRTH's produced and be the exclusive provider of them.

I may need to edit this post when I think more about it, or have more photos to add.

Please check out one of my galleries here - it has other photos of TurboHeads...

Al

Thanks Al, it's great to hear and understand the story behind this little piece of history.

I am using it with the MN16 lamp, and while I'm aware that it's not an 'officially recommended' configuration, the beam is very tight especially compared to the MN16+KT combo, and I am very pleased with it. The hotspot is a little oval-ish, but it doesn't really bother me because the beam collimation is excellent. I would say that this is one of the tightest beams I've ever seen in a flashlight - eloquent tribute to Surefire's engineering.

My own experiences with building hotwire incandescents (the Roar of the Pelican projects in particular) have taught me that while I can easily pack more 'absolute' numbers of lumens, Surefire makes more efficient use of the photons. For example, my ROP Lithium Edition (2C Mag, 2x18650 lithium ion) and bulb combo puts out approx. 600 output lumens, but it is a wide flood. The ROP/LE and the SRTH+MN16 combo achieve the same spot brightness at the same distance, but one has to generate so many more lumens to do that because of the inefficient beam collimation of the metal Mag-replacement reflectors we use.

This was tested one night using the 'resolving power' test. Resolving power is a term in photographic circles referring to how much detail one can perceive, they normally use resolution charts to test the resolving power of lenses. Better lenses bring out more details in the subject.

I'm building my own variation of this test for flashlights. We are using the same pair of lenses (eyes, to be technically correct ) and varying the light. We tested a ROP/LE (600 lumens), KT1+MN60 (225 lumens), SRTH+MN16 (225 lumens). Choose a distant object, to the point where you can barely see the detail. If all lights bring out the same amount of detail as perceived by your eyes you need a more distant subject, so try again.

Once you decide on a point, aim the lights at the same point and test each of them. The light that enables you to see the most detail has the brightest spot. You can check beam collimation by looking at the side of the beam, works better if there's moisture in the air.

The KT1 lost the resolving power test by quite a fair margin, the ROP/LE and SRTH are equal to each other, but the ROP/LE has very poor beam collimation and the only reason why it can match the SRTH in the resolving power test is because of its 3X lumen output. Independent opinions from 4 different pairs of eyes (some with corrective optics, all of varying age) were consulted and the results tallied

The resolving power test is quite a useful one, because the more detail you can pick out at a given range, the easier it is to identify what you are looking at, which is generally what lights tend to be used for.