Paul;
Sounds good. Thanks for the info. Now, where's my protractor ... <g>
George
-----Original Message-----
From: Paul Farrar <farrar@xxxxxxxxxxxx>
To: olympus@xxxxxxxxxxxxxxx <olympus@xxxxxxxxxxxxxxx>
Date: Friday, December 18, 1998 11:57 AM
Subject: Re: [OM] Re: T20 flash and red-eye
>>
>> Soenke;
>>
>> Yes, I think you have a point here. Just thinkng out loud: to banish
>> red-eye the photographer needs to cause the flash-to-eyes vector to be
>> non-parallel by some **reasonable** angle to the lens-to-eyes vector. ie
>> flash **some** distance away from lens. So if the subject is farther
>> away (and you're using a longer , eg 150mm) lens then the distance from
>> the flash to the lens need to be greater.
>>
>>
>> George
>
>Yes, and my understanding is that the angle you need to exceed is 3
degrees.
>The flash needs to be 3 degrees off the eye-lens line. The approximate
>tangent of 3 degrees is 1/20, so the flash-lens distance should be
>greater than 1/20 the eye-lens distance. (I'm the one who posted that.)
>That's why people are saying they get redeye with longer lenses. But it's
>not the focal length that does it, it's that they are taking from farther
>away when they are using the longer lens.
>
>I have not rigorously tested this rule, but it does seem to square with
>my observations.
>
>Paul Farrar
>
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