litefoot@xxxxxxxxxxxxxxx writes:
<< PLs explain how putting the lens would affect the exposure settings of teh
flash?
Calling those who have used an XA4, how could I use ASA 800 or faster
film
knowing that the flash units A11 or A 16 are designed only to work on
ASA
100 and 400?
>>
The idea is if you can gather more light with a larger aperture lens, than
the one on the exsisting phototransistor in the flash, then the sensitivity
to recieved light of the flash goes up. That is, it appears to be set for a
higher ASA. If you gather 2X as much light the sensor thinks the scene is
twice as brightly lit as it really is and cuts off the flash duration sooner
than normal. You should be able to test this with a flashmeter to adjust the
lens to get exactly half the light for 800ASA etc.
Maybe you could put the lens on a tiny tube and attach to the flash over the
photocell hole with velcro or similar sio it is removeable.
One problem is you may change the angle of acceptance of the exsisting flash
sensor with the added lens. A longer FL lens makes it narrower a short wider.
To increase light and make it narrow may be impractical as the lens gets too
big or too far from the front of the flash. With flash meter at least you can
experiment easily.
Regards,
Tim Hughes
>>Hi100@xxxxxxx<<
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