I have been reading about how throw flashlights work and the general idea is that the aspheric lens diameter affects throw but the lens focal distance doesn't matter. In the case of using a Wavien collar whose aperture at the top is made to match exactly the usable angle of light that reaches the aspheric lens, does lens diameter make a difference? That is a 35mm aspheric lens with a Wavien collar and a properly matched aperture would throw the same as a 70mm aspheric lens with a Wavien collar with a different aperture properly matched for that aspheric?
Question about throw and lens diameter when using Wavien Collar
- Thread starter nikosb
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sven_m
Newly Enlightened
The collar doesn't change anything about the effect of lens diameter (if aperture matches so that no light is "clipped of" by the edge of the collar).
The collar just increases the LED luminance. (There's no magic about the aperture involved.)
In your example, if no clipping occurs, then a 70mm lens results in 4 x the spot lux of a lens with 35mm (because spot lux depend on lens diameter squared).
Edit: By the way, the different sizes of the spherical wavien collars all have the same aperture, if measured by angle.
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faeded
Newly Enlightened
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- Dec 21, 2014
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what do ypu mean measured by angle? the top hole is the aperture right? i have been experimenting with making my own collars but dont seem to see much improvement.
sven_m
Newly Enlightened
Yes, and I meant that the light cone coming out of the collars has the same angle, not depending on the collar size
(well, given a point-like sized LED, so there's always some small variation depending on the actual LED and collar size)
Your collar might have a lower reflection than needed or the spherical curve is not sufficiently accurate.
A wavien doubles the LED luminance and thus spot lux.
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