Are all red filters like this??

LEDBE
G

gsegelk

Newly Enlightened
Joined
Apr 17, 2007
Messages
199
Location
Charleston, SC
I recently got one of the Olight Infinitum Ti lights (#23 polished) and I was happy that mine came with the red filter...until I saw that it has white/yellow rings around the red beam!! Don't get me wrong after this post...I love the light but since I don't have any other red filters, I am wondering if this is common??

I like the idea of the red filter b/c a) it lowers the light output, and b) it makes the light less noticeable. This is what I thought the red filter would do, but it turns out that a good bit of white/yellow light is still let through on the edges (see beamshots). B/c of the rings around the red beam, I still can't use this light on its lowest settings without 'cupping' the head to further restrict light output. Btw, the reason I like the option of such a low level is that I usually go to be later than my wife and don't want to wake her up...she's a VERY sensitive sleeper! I previously didn't think 7 lumens would be a big deal but it really is in this case!

One thing to note about these beamshots is that I tried all kinds of settings and light brightnesses to attempt to capture what my eyes are seeing but I couldn't get the right combo down...I doubt it's even possible with my setup (Panasonic LX3). In order to try to show what I'm talking about, the pics were taken with the light at its brightest setting. The part that I just couldn't seem to get was the spill of the white/yellow light around the red center. On to the beamshots...

Underexposed a little (light is on high)...
IMG_4825.jpg



Closest to what my eyes see (light is on high)...
P1000218.jpg



Probably the best shot...
P1000223.jpg


Notice in the shot above how small the red beam is compared to the yellow spill. Just from my observations, light going through the filter at an angle is the yellow light...light that passes straight through (perpendicular) to the filter is the red center.

So do other red filters have the same characteristic or is it just the one I'm using??
 
I think it is just that one.
:barf:
It sucks!

Can you give us a close pic of the light turned off and looking straight into the filter (while on the light).
 
Thanks! It's good to know that I shouldn't give up on red filters! Don't know about others, but this filter has a mirrored finish to it but I was able to get it:

P1000240.jpg


P1000243.jpg
 
It's almost like the red coating stops just a hair before getting under the rim of the black mount. :thinking:

Can you pop the lens out of it? If I'm right hitting that edge all the way around on both sides with a red Sharpie might help. If you can't remove the lens you might be able to still do it.

If I am wrong about where the red coating ends, well, you really need to find another red filter!
 
Last edited:
Sgt. LED said:
It's almost like the red coating stops just a hair before getting under the rim of the black mount. :thinking:
Click to expand...

That's what I thought at first too. There's actually a good amount of overlap:

Note the recessed area where the filter goes...
P1000257-1.jpg


P1000252-1.jpg





Sgt. LED said:
Can you pop the lens out of it? If I'm right hitting that edge all the way around on both sides with a red Sharpie might help. If you can't remove the lens you might be able to still do it.

If I am wrong about where the red coating ends, well, you really need to find another red filter!
Click to expand...

I also tried the sharpie idea on the edge, thinking that light might be somehow refracting through it. I had the filter out when blacking out the edge and noticed this (follow the three pics...):

Straight-on shot:
P1000260.jpg


Angled (~45 degrees):
P1000261.jpg


Angled more:
P1000262.jpg



I'm not a red filter expert or anything, but it appears that this filter is only good at filtering light that passes directly through it?!? The yellow rings are being caused by the sidespill.

Is there something I could use from a common hardware store that could be cut to fit and actually filter light from all directions??

Thanks for taking interest in my big drawn out red filter issue :thumbsup:!!
 
http://www.pssl.com/Rosco-Roscolux-Gel-Sampler
Really cheap but great filters! Loads of colors and LDF!
There are lots of more expensive options out there but I like saving people money.

If you could find a clear lens the same size as your awful red one you could put some Roscolux between it and the light.

Your lens would work well in a Mule! :whistle: What size is it? I might have to try and buy it from ya!
 
Last edited:
I could only replicate that with the light/filter within ~6" of a white wall.

Are you seeing this outside of those extreme short ranges?
 
that doesn't look like a red filter at all, it looks like a red polarizer on a quarter wave plate, aka a circular polarizer. It would be used to filter collimated light sources and not something inside a parabolic or curved reflector surface at all.

In essence, that is far more complicated filter technology than what should be on a flashlight, which is funny because its no good for that simple purpose.

You need a real red filter.

See if you can find a pair of polarizing sunglasses. Put the sunglasses on and then look at the filter with a regular house lamp as a light source.
Flip the filter over and see if its polarized and darkens the light from one direction only. Rotate it also in each position. If it darkens when flipped over with regards to the direction of the light source to you, its really a circular polarizer, which is a quarter wave plate with red polarizer film on top.

Here is some basic reference material.

http://www.camerapedia.org/wiki/Polarizer

Who makes that filter specifically.

I can't help but wonder what it would do in front of a TIR optic type light source, Inova or the infamous E2DL Sure Fire???
 
MrGman said:
that doesn't look like a red filter at all, it looks like a red polarizer on a quarter wave plate, aka a circular polarizer. It would be used to filter collimated light sources and not something inside a parabolic or curved reflector surface at all.

In essence, that is far more complicated filter technology than what should be on a flashlight, which is funny because its no good for that simple purpose.

You need a real red filter.

See if you can find a pair of polarizing sunglasses. Put the sunglasses on and then look at the filter with a regular house lamp as a light source.
Flip the filter over and see if its polarized and darkens the light from one direction only. Rotate it also in each position. If it darkens when flipped over with regards to the direction of the light source to you, its really a circular polarizer, which is a quarter wave plate with red polarizer film on top.
Click to expand...
You don't need sunglasses to test this. A simple LCD monitor (like the one in the background of the photo of the filter) will be emitting polarized light and can be used to test your theory. (try looking at your monitor with sunglasses to see what I mean...) I suspect gsegelk would have noticed this effect while taking the photo if this were in fact a polarizer.



This looks like a thin-film dichroic filter to me: http://en.wikipedia.org/wiki/Dichroic_filter

That is, a filter that transmits red light, and reflects back other colors. Simple filter such as the rosco linked above are absorption filter -- which pass red and absorb all others (dissipating the energy as heat, which may fade the filter over time).

Advantages of dichroic filtres is that the frequencies they pass can be much more accurately controlled, and they can be almost 100% efficient (a red absorprtion filter will actually block a non-trivial amount of the red light you WANT as well as the other colors you dont). The bigger advantage however is that the filter isn't absorving any energy -- that's important if you're trying to filter something extremely concentrated like a high-energy laser, or if you want to collimate two laser beams of different colors with each other.

An absoprtion filter would heat up and become damaged if exposed to a high-energy laser. Of course, that's totally irrelevant for a flashlight. This is unsuited for flashlight use. Because it's sensitive to incidence angle. That means that spill light will make it straight through. Not only that the fact that the dichroic filter will reflect the non-red colors, causing them to re-strike the aluminum reflector in the light, bounce back out at a different angle and eventually make it past the filter (as spill).
 
Last edited:
If it doesn't have any polarization effect, I think you are right. I didn't think of the dichroic filter. Again, too much technology to put in front of a flashlight source with a parabolic reflector, its still better in front of collimated light. Makes for pretty color effects.
 
Bobo The Bear said:
Sorry to sidetrack this thread a bit, but I've been looking for red filter solutions for various AA and AAA flashlights. What should I be looking for in that link?
Click to expand...

the sampler pack gives you about 100 or so sheets of assorted filters.
you can cut them into disks and mount them behind your lens to
get the filtering effect. these are all high quality professional filters.
they have no problem handling the heat from the led and wont discolor/warp over time.

they have some filters in there that you can use to convert crappy led tints
to nice warm incan style tints. it does cost you from .5 to 2 stops, but you
would lose some brightness swapping in a warmer led anyway.
once i get my ld01 ss open, instead of swapping the led, i'm going to hide that green led behind a filter. :naughty:
 
MWClint said:
the sampler pack gives you about 100 or so sheets of assorted filters.
you can cut them into disks and mount them behind your lens to
get the filtering effect. these are all high quality professional filters.
they have no problem handling the heat from the led and wont discolor/warp over time.
Click to expand...
Yeah, LEDs will be fine. When I posted about the heat, I was thinking that this was an incan flashlight.

they have some filters in there that you can use to convert crappy led tints
to nice warm incan style tints. it does cost you from .5 to 2 stops, but you
would lose some brightness swapping in a warmer led anyway.
once i get my ld01 ss open, instead of swapping the led, i'm going to hide that green led behind a filter. :naughty:
Click to expand...
Trust me, switching to a warmer bin will be a MUCH more efficient approach. Dropping a very cool WC LED down to match a 5A will cost you about 2 stops (read: 50% cut in output). Swapping in say a Q3 5A, compared to a R2 WC will cost only 18%.

Also, in my experience (I do have the exact Rosco filter book talked about), filtering can't help many cool white LEDs which suffer from a fundamental lack of red light output. Applying heavy CTO filters simply makes the output look green, rather than warm-white. The LEDs don't have a continuous spectrum like the Halogens that the Rosco filters are designed to filter out.

The warm- and neutral-white LEDs actually have different phosphors as well so it's not just a matter of improved efficiency compared to using filter, but improved color quality as well.
 
2xTrinity said:
Trust me, switching to a warmer bin will be a MUCH more efficient approach. Dropping a very cool WC LED down to match a 5A will cost you about 2 stops (read: 50% cut in output). Swapping in say a Q3 5A, compared to a R2 WC will cost only 18%.
Click to expand...


haha, i guess the 2 stop penalty is one way to get a lower low out of a fenix. :nana:
all my aaa feni have had crap tints and have gone through led swaps. at least my l2d/p2d is nice and my wife's l0d q4 is nice.
I've yet to try a warm cree, so i might as well order a few for some projects. thanks for the advice/warning.
 
Last edited:
any color filter be it from rosco, gam, apollo, or lee is made for a halogen lamp which has a wider spectrum of red, yllow, and magenta (red+blue). I know this for 2 reasons, first off I am a theatrical lighting designer and technician, secondly I am a flashaholic with all led lights and swatch books from each of the above manufactures. Red pink and amber gels won't work well with white LEDs ( cool white) due to there being very little red in the spectral emission of a cool white led.
 
If you want to warm up the tint of the bluish SSC P4 LEDs cut out circles of # 3410 and #3406 from your roscolux sample books the result is a warmish tint similar to that of a K2-TFFC.
 
I love that sample pack!

CSSHIH, what are you after? I think we need to do a group buy to get past the shipping cost! :twothumbs


I get results from using the reds with an led but since I know ahead of time the losses involved I just adjust the output up a bit to compensate.

Not perfect sure but good enough to get by.
 
Try out lee filters, gam, and Apollo as swell they offer free sample books. Links:
lee: www.leefilters.com
gam: www.gamonline.com
apollo: www.internetapollo.com
just find the info request link and when asked to select what you want info on check off "swatch book"
FYI: rosco sample books used to be free and I have like 10 of them so pm me and I'll see if I can send you one.
 
Last edited:
You must log in or register to reply here.

Similar threads

Orion
Flashlight You Sometimes Like, Other Times Don't Like
2
Replies
26
Views
1K
jon_slider
J
MidnightDistortions
Seems like all the 4 AA lights are gone
2
Replies
31
Views
4K
DaveTheDude
D
Orion
Titanium Flashlights Are Heavier?
Replies
9
Views
624
jon_slider
J
Lips
P60 Host - Like Seraph Unmarked OEM
2
Replies
33
Views
3K
muichimon
muichimon
M
P60 red Drop in
Replies
3
Views
765
md17
M

Latest posts

Top