Flash Extender Construction Help


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afiend

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Jan 17, 2002
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#1
Hi everyone

I am constructing a flash extender. However I am unsure of the distance to put the fresnel lens.

I have tried different combinations, like putting the lens before and after the focal point of the lens.

However I am unsure which and what is right. The concept is to extend the range of the flash. But is it suppose to concentrate the light into 1 spot or diffuse it around the area?

If you have pictures do post...
 

willyfoo

Senior Member
Jan 18, 2002
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willyfoo.com
#2
Originally posted by afiend
Hi everyone

I am constructing a flash extender. However I am unsure of the distance to put the fresnel lens.

I have tried different combinations, like putting the lens before and after the focal point of the lens.

However I am unsure which and what is right. The concept is to extend the range of the flash. But is it suppose to concentrate the light into 1 spot or diffuse it around the area?

If you have pictures do post...
Put it much nearer than the focal point. I started with the focal point... and I noticed that I can actually see the shape of my flash in the pix cos it was too focused... the idea is just to gather light around the central area.

If you are using the standard fresnal lens you buy at Popular Book Store... I remember the focal length to be about 17-18cm.. You might want to put it about 14cm... (Then it can fold nicely with the lens as well.)

You might want to see the pix below for an approximate gauge...

Your mileage may vary..

Good luck!
 

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