Convoy L4 Flood-Beam Film - Lots of Superfluous Pics

So the Convoy L4 was a bit of an impulse buy, but whatever it's a nice light all round. I don't like it's tight hotspot though so I wanted to make it more floody. I bought some film that is used in interior design and is known as "Privacy Film" and is used to stick over windows. It's also known as "frost film" and other names. After you stick it on the window you basically can't see through it at all. Anything behind the film is completely blurry and you will only be able to make something out if it was pressed against the glass. Just 1cm away and it's blurry. It's easy to work with, can be repositioned, washed, and cut to size; very forgiving. So I bought a "sample" from an Australian "ebay seller " which turned out to be 80x150mm, enough to do a few torches with. Did I mention it cost $1!

The film

Thickness against a Post-It Note. The note was .10mm and the film .21

Standard L4 (4C tint). Camera settings ISO 80 4.0 .5sec. Note the shadow around the corners are just a tiny bit brighter in reality. If I exposed it longer the hotspot started to look too bright than what I saw. Overall it's quite accurate.

Knife. Sharp is best.

Place the lens down, cut around it. Please cut AWAY from your hands at all times.

Almost a circle.

Don't get your oil on the film. Squeeze it between the knife and your finger.

Squeeze out those bubbles!

Hmm nice. Looks like a culture sample/petri dish.

Don't mind the white spot. It's a glitch in the matrix. har har

End result

And the old for comparison again

I changed the aperture from the before and after photo intentionally as the same settings didn't resemble how the hotspot appeared. It would look much brighter than it was so the changes actually compensated for the difference and both look like reality.

Big big difference. You can see the film fills in all the dark gaps around the side making it much more of a useful beam in close range. Long distance light has been completely lost, however this is still very competent in lighting up your entire yard area well. And really, a light used anywhere within your home or immediate surroundings doesn't require huge throwing power.I might order the Fasttech OP reflector and compare but this is pretty good as it is.

Thanks for reading.

thanks for sharing!

looks very nice!

Nice and simple $1 mod idea. This Spark light also has the lens included at a steep price point.


Nice thing is…reversible :slight_smile:

Easiest and infinitely more practical is using a plug-in filter like this :
Fits C8 and L4.
This way you can easily switch between the two beam patterns, even more useful than a zoomie.

Oh I was looking for one of those. Couldn’t find one in the 45mm but thanks. Does add a bit of bulk.

Wow, now I'm thinking of buying another L4 and doing this to it, and also some other lights I have lol. I'm also wondering how the beam would look like if you cut a hole about 10-15mm right in the center of this plastic, and maybe have a slight hotspot and all that wonderful superflooder as well. Maybe you could make one and test it out? Like the best of both worlds? Or I'm wondering if the hole for the hotspot will take away most of the flood that your diffuser is providing diffuser. Could you test this?

Most of the spill comes from light that has not 'touched' the reflector , the hotspot is created by light which has been 'concentrated' by the reflector ....

I use DC-Fix on a lot of lights , I love smooth beam profiles .

Demi I would be happy to oblige but Jack is right. The whole in the middle wouldn’t give you a hotspot, it comes from the surrounding areas.

Some annoying questions rise:
Light transmittance…?
Okay, it’s just one question…
But how much out-the-front-lumens would this cost?
I like the resulting flood though, but this stuff leaves you not much throw…
I suppose you could remove parts to regain some throw.

I believe the light loss is around 2-3% with DC-Fix .

But yes , throw is lessened . How much depends on how concentrated the hotspot is before the diffusion .

Simple mouseover:

seens nearly unbeliefable… - same Kamerasettings?

You got really nice pictures of the result. Much better representation than any attempt I’ve made so far.

I use DC-Fix on several lights, but I don’t really understand using it on a thrower when you can get the same beam out of something much smaller. Instead of a Convoy L4, you could do this with a Convoy S2. I think the items I’m currently using DC-Fix on are: ZL SC52, CNQG brass beauty, Convoy S3-XP-G2, Convoy S7-219B, and BST-wide. And the ZL H52Fw looks similar due to its frosted lens. The BST is sort of an odd choice for diffuser film since it has quite a bit of throwing potential, but I went for wide-spectrum with lots of floody lumens instead.

When I put diffuser film on a removable lens, I find it easiest to put it directly onto the sticky side of the film, cut around it with a thin, sharp knife, and then just leave it on. Maybe push out some bubbles first, but mostly just pop the lens right back in. No need to remove it and trim the edges further. If I can’t remove the lens though, things get a little more tricky. Then I need to find a stencil of just the right size to cut around, like a coin with the same diameter as the exposed portion of the lens.

No. From the OP: “I changed the aperture from the before and after photo intentionally as the same settings didn’t resemble how the hotspot appeared.”

Side by side, the two beams would look more like this:

(except that photo doesn’t really show how wide and smooth the spill is for the light on the right)