Has anyone ever made a TL-2.5?

I know the suggestion of downgrading a light might be heresy on CPF, but I'll make it anyway!

Simple idea: A TL-3 modified to run a TL-2 bulb. Using 2x123s and a spacer, instead of 3x123s.

Expected result? Not as bright, and not as throwy, but much cheaper to run.

I haven't tried it yet, but I'd expect the results to be rather good. And I'd also expect it to still be very throwy, when compared to a normal TL-2.

Has anyone tried this yet?

Should I get my coat?

Why not use rechargeables in a regular tl-3? You keep the brightness and throw without having to buy expensive primaries.

sancho886 said:

Why not use rechargeables in a regular tl-3? You keep the brightness and throw without having to buy expensive primaries.

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Quite. That seems to be a popular thing for a lot of people. This probably makes the TL-2.5 seem even more silly to a lot of people.

For me, though, I prefer to stick with primary 123s. My use for the TL-3 is always when out in the wilds, so I prefer the idea of sticking to primaries and carrying spares.

I wanted to do the opposite, TL3 bulb in a TL2 body and apparently they will fit in one another (according to Dano) however the focus of the light will be off due to the different heights of the filament.

If using the light in a place where you can recharge batteries going to the rechargable battery setup is great. Much brighter and more throw than using primaries.

Greg said:

...however the focus of the light will be off due to the different heights of the filament.

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Thanks for the info. I've just compared my TL-3 bulbs vs TL-2 bulbs. Yes, the TL-2 filament appears to ride a good couple of mm lower than the TL-3 filament.

What a shame. But at least it isn't the other way around. This way, it is possible to put a little 2mm spacer under the bulb. But that would be too much like getting into "proper" modding for my tastes. E.g. there may be issues about the 2mm spacer handling the heat. And the fact that 2mm less contact between the bi-pin legs and the socket could mean the bulb falls out easily.

I'll get my coat, then.

Double post

I run a TL3 bulb in a TL2 body with Li-Ions and quite like it. I didn't even notice any filament height difference (didn't look), and I was able to get a very tight focus with no trouble. It's great!

Galiphrey said:

I run a TL3 bulb in a TL2 body with Li-Ions and quite like it. I didn't even notice any filament height difference (didn't look), and I was able to get a very tight focus with no trouble. It's great!

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I can see it working well that way around, i.e. a TL-3 bulb in a TL-2 body (by just unscrewing the head a bit further than usual.)

However, since the TL-2 bulb filament rides about 2mm lower, and my TL-3 head, when in tight focus, can only be screwed down another 1mm (roughly), it looks like it won't be possible to focus it properly with the configuration I was thinking of.

Oh, yes, I see. Let me hand you your coat, here....

I don't see the issue with the focus since TL-2s and TL-3s have adjustable focus and will likely account of most of the difference in the focal point.
I see OutdoorIdiot's point with sticking with primaries in the wilderness...I'd do the same. I don't see a problem running a TL-2 bulb in a TL-3.
I've been thinking about running a TL-3 bulb in my TL-2 with 2x R123As, but since just picking up my TL-3 is easier and it runs off 17500s, I haven't done so. Plus, I use my TL-3 mainly for night walks and fooling around, so my situations are fine for rechargables.

jsr said:

...TL-2s and TL-3s have adjustable focus and will likely account of most of the difference in the focal point.

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That was what I was hoping for, when Greg mentioned the difference in filament heights. Looks like it won't work, though. Using a TL-2 bulb in a TL-3, one would need to screw the TL-3's head down roughly 2mm more than usual for tight focus. However, my TL-3 head only has about 1mm to go before it hits the main body. Not sure if I'm explaining that well, but I can picture it because I'm looking at all the bits in question as I type this...

Edit: BTW, thanks for my coat, Galiphrey. It's always good service here at CPF!