The SF A2 - Part 2

[DM51]

I think that I may have the world's largest collection of Aviators outside of factory or dealer shelves at this point.

You can't count the one you vandalised with your chainsaw. Photos of that one would probably be even more upsetting than the pics of nauss's L1 after his uncle chewed it up with his John Deere tractor.

 

[Atomic_Chicken]

Greetings!

You can't count the one you vandalised with your chainsaw. Photos of that one would probably be even more upsetting than the pics of nauss's L1 after his uncle chewed it up with his John Deere tractor.

Chainsaw??? My good man... credit me with a bit more finesse!
It was a lathe and milling machine. Carbide tooling at high RPM - mirror smooth finish and all that. Chainsaws are for dolts and mass murderers!

Best wishes,
Bawko

 

[js]

Daniel_sk (and others),

Thanks for your kind words! The A2 review I did (part 1) was definitely a labor of love and involved a lot of time and effort, research, field testing, pictures, thought, and so on. And the funny thing is that it wasn't finished when I posted it. But I was like "It will never be finished. I've got to post something for now."

At this point, I'm thinking that Atomic_Chicken should do part 2 for us. I never could bring myself to sacrifice an A2 for the sake of knowledge, as much as I really wanted to show the internals and the LVR3L and o-scope pictures and all that. Well, I can get oscilloscope pics without destroying an A2 . . .

But anyway, Bawko is now probably the premier CPF expert on the A2. I think he should post the review that would have been "part 2" of my review. [muttering to self]Yeah. Bawko should do it. Get the new blood to do the dirty work. Time to relax. hehe[/muttering]

 

[Minjin]

Minjin,

Well, the proof is really in my experience... <snip>So, the proof comes from my practical, empirical experience....<snip>

That's what I've got. I hope it's more or less palatable for you!

Since you're calling me out in another thread for asking a simple question here, I'll respond... :shrug:

The above snipets are what I was getting at. You say that if you align the filament such that the focus is the best (i.e. intensity is the greatest), it throws the furthest and also happens to have an oval beam. This is different from saying that the oval beam CAUSES it to throw better.

I don't see there as being anything inherently better in the structure of an oval, but it certainly could be. Thats why I asked if you had a proof. And by that I was thinking in the mathematical sense.

If you take a circle and squash it down to an ellipse, yes you are increasing intensity. But if you take a circle and stretch it out to an oval (keeping the area the same), I don't see it as increasing intensity and thereby not increasing throw. This latter part is what I think of when you say that an oval throws better. Because to be a true comparison, you need to compare it to something of equal area. Yes, I know that we should be thinking in terms of volume, but lets keep it simple for now.

 

[DM51]

Since you're calling me out in another thread for asking a simple question here, I'll respond... :shrug:

The above snipets are what I was getting at. You say that if you align the filament such that the focus is the best (i.e. intensity is the greatest), it throws the furthest and also happens to have an oval beam. This is different from saying that the oval beam CAUSES it to throw better.

I don't see there as being anything inherently better in the structure of an oval, but it certainly could be. Thats why I asked if you had a proof. And by that I was thinking in the mathematical sense.

If you take a circle and squash it down to an ellipse, yes you are increasing intensity. But if you take a circle and stretch it out to an oval (keeping the area the same), I don't see it as increasing intensity and thereby not increasing throw. This latter part is what I think of when you say that an oval throws better. Because to be a true comparison, you need to compare it to something of equal area. Yes, I know that we should be thinking in terms of volume, but lets keep it simple for now.

wtf is all this nonsense?

 

[greenLED]

Chainsaws are for dolts and mass murderers!

Hey, I resent that! I used to make a living wielding a chainsaw (and I won't say which one of the two categories I put myself in). :nana:


Who cares if the beam is oval, round, square or heart-shaped? Really, guys - what matters is that a light goes on/off when you need it and does what you *need* (not want) it to do. That's all there is to them.

 

[SCblur]

Since you're calling me out in another thread for asking a simple question here, I'll respond... :shrug:

The above snipets are what I was getting at. You say that if you align the filament such that the focus is the best (i.e. intensity is the greatest), it throws the furthest and also happens to have an oval beam. This is different from saying that the oval beam CAUSES it to throw better.

I don't see there as being anything inherently better in the structure of an oval, but it certainly could be. Thats why I asked if you had a proof. And by that I was thinking in the mathematical sense.

If you take a circle and squash it down to an ellipse, yes you are increasing intensity. But if you take a circle and stretch it out to an oval (keeping the area the same), I don't see it as increasing intensity and thereby not increasing throw. This latter part is what I think of when you say that an oval throws better. Because to be a true comparison, you need to compare it to something of equal area. Yes, I know that we should be thinking in terms of volume, but lets keep it simple for now.

I'm kinda jumping into the middle of all this, and I don't mean to interrupt an ongoing conversation. However, the explanations I've heard in the past from CPF'ers about the oval spot, had less to do with mathematics, and more to do with the fact that the filament in an incan bulb is not a single point of light, but a bar. They went on to explain that if you want to maximize the throw of any point source of light, the general shape of the light source (the filament 'bar' in this case) is projected forward into the hotspot. Smoothing, or rounding out, the beam would involve taking the filament slightly 'out of focus' to use a photography metaphor. And in doing so, the beam is made more diffuse and round, but some throw is sacrificed. This is, anyway, how I understand it. Albiet, I'm not an engineer, but it makes good sense to me.

 

[js]

Minjin,

Pretty much what SCBlur said.

However, specifically, you say:

You say that if you align the filament such that the focus is the best (i.e. intensity is the greatest), it throws the furthest and also happens to have an oval beam. This is different from saying that the oval beam CAUSES it to throw better.

And in point of fact, I never said that the oval beam causes it to throw better. You're the one who quoted me above, right? Here's what I said:

The oval beam is oval by design! If the beam were round, the throw would be less.

My experience regarding the focus of transverse filaments in parabolic reflectors is pretty general. It's completely true that "if the beam were round, the throw would be less." The oval beam is a design choice. The SureFire engineers opted for better throw at the expense of beam aesthetics. It was a trade off. It was deliberate. And it goes hand in hand with better throw.

A whole lot of people have posted about the oval, squashed beam of the A2 as if it were just an outright flaw, a failing, something that could have been easily fixed if only the engineers at SureFire had just cared enough. The same way that people post about the LED's being on when the incan high beam is on--as if it were an awful black spot on the design of the A2, that SureFire should have been smart enough to avoid.

Not so.

It's just physics, baby, and if you really understand how the A2 gets away with being a dual mode light despite the single ground return path, then you understand why the LED's simply had to work they way that they do work.

And just so, if you understand how a line source gets focused in a parabolic reflector, and how the beam responds to different focal points, then you understand that for the best throw, the beam will necessary be oval. The only way to avoid this would be to make a reflector that was itself an ellipse (oval) in cross-section in the horizontal plane (plane of the lens), and parabolic (of varying p's) in cross-section in the vertical plane (in any plane perpendicular to the plane of the lens).

But take a single parabola and make a parabolic reflector by sweeping that parabola around, and there is no way to have both a round beam and the best throw.

The A2 beam doesn't just "happen" to be oval, in other words.

And, I did call you out in another thread, but it was to ask if you were mad at me. Because, usually, when someone takes the time and effort to try to respond fully, honestly, and with some amount of detail to a question you have asked, you at least say "Thanks". That and you getting a chuckle out of my approbation of the Aviatrix because I was somehow too slow to understand that I wasn't supposed to like uC lights (which I never said). But let's leave that to the other thread.

 

[Atomic_Chicken]

Greetings!

js... technically, the A2 is a dual-mode light despite a single positive return-path, not a single ground return-path as you stated in your post. However... that's kind of splitting hairs and isn't really germane to the conversation.

I personally think, after examining all aspects of the A2 design, that having the LEDs on while the incandescent bulb is on is actually a design FEATURE... a deliberate design decision meant to address a specific failure mode. In the event that you are using your A2 and the incandescent bulb fails, having the LEDs already on insures that you won't be left "in the dark" so to speak. I can think of half a dozen ways that Surefire could have designed the A2 to turn OFF the LEDs when the incandescent bulb is on, most of which would be simple, reliable, and inexpensive to implement... but the rest of the A2 design is so perfectly thought out and executed that I have a hard time believing that this was an "oversight". As I previously stated, I believe that it was a deliberate design choice - and that that A2 is a better light because of it!

Best wishes,
Bawko

 

[js]

Bawko,

OMG! Yes. Sorry. You're right. The LVR switches the negative. Damn. Forgot about that.

Yup. My point is just that the LVR is actually powered up when the LED's are on, it's just smart enough not to fully turn on, smart enough to know when there is that extra resistance in circuit (in the tailcap).

 

[Minjin]

My experience regarding the focus of transverse filaments in parabolic reflectors is pretty general. It's completely true that "if the beam were round, the throw would be less." The oval beam is a design choice. The SureFire engineers opted for better throw at the expense of beam aesthetics. It was a trade off. It was deliberate. And it goes hand in hand with better throw.

The A2 beam doesn't just "happen" to be oval, in other words..

The oval beam is a design consequence not a design choice. According to you, they leaned the compromise towards throw and did what was necessary to achieve that. I highly doubt that at any point in time, they sat around and said "we need a beam that throws...I know, lets go with an oval beam!" I think you're not seeing the larger picture. My interest in the oval vs circle has nothing to do with the A2. I was just wondering if the statement that oval is better is true, then why aren't we designing other lights such as ones with LEDs to have an oval beam? I'm also very interested from a physics standpoint to know if certain light patterns are optimal. To get the maximum intensity with a parabolic reflector, the filament must be aligned in such a way that it ends up creating an oval beam. I buy that. What I wasn't buying is that an oval beam is any better than a circular beam with the same intensity.

And, I did call you out in another thread, but it was to ask if you were mad at me. Because, usually, when someone takes the time and effort to try to respond fully, honestly, and with some amount of detail to a question you have asked, you at least say "Thanks". That and you getting a chuckle out of my approbation of the Aviatrix because I was somehow too slow to understand that I wasn't supposed to like uC lights (which I never said). But let's leave that to the other thread.

I think you have a little too much anger in you today. I hadn't responded to your answer here because I hadn't gotten around to it yet. As for the Aviatrix, it was a humorous post that was supposed to be responded to in a like way. But both of you guys must have got up on the wrong side of the bed. :shrug:

 

[SCblur]

It sounds to me like you guys are saying pretty much the same thing.

 

[js]

Minjin,

Yeah . . . I was having a bad hair day yesterday. I'm sorry.

(deep breath) OK. Moving on, yes, I see where you are coming from, and yes, you are completely correct: there is nothing better about an oval over a circle from a physics standpoint:

To get the maximum intensity with a parabolic reflector, the filament must be aligned in such a way that it ends up creating an oval beam. I buy that. What I wasn't buying is that an oval beam is any better than a circular beam with the same intensity.

I totally agree with you. Because, like you say, if that were the case, we'd be seeing LED lights with oval beams, and to my knoweldge (limited) there aren't such lights. My Arc LSH has a squarish beam, but that's because the LED die is square and that transfers through the optic and ends up in the beam profile.

Anyway . . . I'm sorry. Please accept my apology.

 

[yaesumofo]

I figured I would revive this thread. I have a question for you guys how have more than one A2 of different colors.
What color are your A2's leds and which are your favorite?

Mine are white (surefire white on my A2 is light purple)

I have seen A2's going for pretty good prices recently. most are green and white. No red no yellow green.
I would love to have a red...I think.

My other question is for those of you who have A2's with color led's is how does the LED color effect the overall color of the Inca light when on?
I assume the Leds stay on like they do on my A2...
Any answers appreciated.

With the distribution of FiveMegas strion socket the A2 has really become an even better flashlight. IMHO
Thanks in advance.
Yaesumofo

 

[Codeman]

I have a white and a red. The red was horrible - it looked like 3 Olympic rings. The tint and flux were fine, but the rings drove me crazy. I put an Aviatrix in it, so I never tried sanding the LEDs any to see how much that would help.

 

[davidra]

I've had all colors. I've never noticed much of a change in color of the overall beam except when it's right against the wall, but yes, the LEDs are always on when the incan is on.

Fewer reds and Y/G around because they are the most useful IMHO. The beam on the red and the Y/G is ugly, but the utility in a dark room is great. I personally like the Y/G better than any of the other colors; it's just the right dimness for a darkened room and preserves colors to a much greater extent than the red. Blue and green are much brighter. If I were using the LED's for a walk outside, I'd go with white or green, but both are too bright for really dark settings when you just want to see what's where in the darkened house.

 

[yaesumofo]

The White Leds in my example are not very white the tint is just terrible.
I wonder how effective and difficult it is to change them out.
Any recommendations?
I want to stick with white emitters in this unit.
I wonder if an emitter switch out is possible with the red units as well improving the red tint. If it is too bright is it possible to add a resistor to reduce the output?

Which color is used in cockpits? The light is billed as a light for aviation. what colors is best for this type of use.

For me I am pretty sure a red would be fine.

I have to say that for all of the sophistication I have always been suppressed that the Leds remain ON when the Incandescent globe is illuminated.
It would seem to me that having the emitters switch off would also save a little energy which is now being wasted.
Has anybody worked on this? Is there a way ..a circuit which can be placed on the Emitter ring which could either sense a voltage drop (when the incan is turned on) and use this signal to kill the energy to the emitters? What about a tiny light sensor if it sees the bright light from the globe and again shuts it down.
I suppose this is not terribly important to users of the white emitters but what about colored leds which may tint the incandescent light.
OK I am just sort of typing off the top of my head. The technology which is in the A2 is actually pretty old compared to what is out there today. IMHO it might be time for a refresh of the A2.

Since we now have new driver technology maybe a more sophisticated system for powering the Leds could be implemented.
IMHO this would be cool. It might even be nice to set up the A2 with some high power emitters.... 3 Crees? Wow! then replace the globe with a red green yellow or blue single LED...sort of switch things around.
OK OK I know I am nuts and I will stop now.
I know I am bordering on heresy here.
Believe me I love my A2 as much as the next guy. I have had mine for years...since the Supreme CO HK Black A2 days a couple of years ago.

I just looked it up and found that I bought my A2 for $119 + $16 for delivery $135 delivered... Not bad really. they seem to be going for about the same these days.
OK I will shut up Please feel free to shoot down my ideas or add to them.
Yaesumofo

 

[SilverFox]

Hello Yaesumofo,

I have run into several pilots who carry A2's. While the most common LED color is red, several have changed over to Y/G saying that in spite of the beam artifacts, it is "more useful" in the cockpit.

Of course, your mileage may vary...

I view the A2 as having 2 lights in one body. A dim light for low level lighting and a reasonably bright light. The white LED's are too bright for low level lighting situations, and I agree that the tint could be improved upon.

However, we are involved in a variety of lighting conditions. In the wilderness with no ambient lighting, the Y/G is also too bright, but in the city with lots of ambient light, you can't even tell that it is turned on. There the white LED's are a better choice.

As far as tinting the beam goes, I don't think there is much influence from the LED's once you get past a couple of feet.

Tom

 

[MikeLip]

Hello Yaesumofo,

I view the A2 as having 2 lights in one body. A dim light for low level lighting and a reasonably bright light. The white LED's are too bright for low level lighting situations, and I agree that the tint could be improved upon.
Tom

I noticed on my A2 the white LEDs were much brighter than I expected. It seems to me that it would be a simple thing to swap the dropping resistors on the circuit board for a higher value, dimming the LEDs. If you were good with a soldering iron anyway

 

[MikeLip]

<deleted> - doggone CPF freezeups