Re: [OM] Close up photos with the 50/3.5 + 4Ti + F280 + ext tubes

Subject: Re: [OM] Close up photos with the 50/3.5 + 4Ti + F280 + ext tubes
From: "Terry and Tracey" <foxcroft@xxxxxxxxxxxxxxxxxxxxxx>
Date: Sat, 7 Aug 1999 18:50:24 +1000
> 1-Is there any easy way of recalculating the TTL OTF (Normal Auto) mode
> Super FP mode tables in such a way that a specific amount of extension is
> taken into account? In other words, does anyone know the correlation
> the amount of milimeters added in extension and the loss of light (in
> stops)? If this correlation is known, it should be possible to recalculate
> these tables rather than creating them by means of test shots. This
> information would be handy for determining the minimum working distance
> between the F280 and the subject.

If all your magnification is due to extension, it's simple. Light loss is
magnification +1. So if you are at 1/2 magnification, the effective aperture
is 1.5 times the setting aperture. A setting of f8 will give an effective
aperture of about f12. You have lost 1 stop.

I've done rough calculations in my head, held the flash as about the right
distance, and had great results.


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