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From: smh@mhuxl.UUCP (henning)
Newsgroups: net.rec.photo
Subject: Re: Flashes and telephoto lenses
Message-ID: <637@mhuxl.UUCP>
Date: Sun, 23-Mar-86 22:05:22 EST
Article-I.D.: mhuxl.637
Posted: Sun Mar 23 22:05:22 1986
Date-Received: Tue, 25-Mar-86 03:56:57 EST
References: <1587@watmath.UUCP> <263@noscvax.UUCP> <633@mhuxl.UUCP> <1881@hammer.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 16

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From the keys of Steve Henning, AT&T Bell Labs, Reading, PA mhuxl!smh

> In article <1587@watmath.UUCP>, rayazwinski@watmath.UUCP (Yazwinski) writes:
> > I have heard that when using a flash and, say a 135mm lens you have to
> > change your f-stop to allow for the light loss through the extra glass.
> > I have also heard that f4.5 is f4.5 no matter which lens you use.
> 
> Isn't anyone going to point out the obvious?  You need a tele-lens on the
> flash to concentrate the light on the area covered by the lens.

"need"??????  You don't NEED a tele filter for the flash unless you don't
have enough light otherwise.  You can use the tele filter, but you normally
don't need it.  Interestingly they suffer more from light loss than
you 135mm tele lens does.  The 135mm telefilter for a flash should give
you 2.5 to 3 stops more light but in fact usually gives 1 stop.