Re: Vivitar 283 Flash Questions

Aren't these the guide numbers you need?  For 1/2 power open up one stop
(i.e. the guide number would go from 160 to 110 as in f/16 to f/11--if the
full power g.n. is 100 1/2 power is 100/1.414 about 70 (the 1.414 is the
square root of 2--just like f/stops).  1/4 power is two stops g.n would be
50, etc.

--
darkroommike

----------
"Phil Duff" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> On Fri, 29 Aug 2003 18:51:19 +0000 (UTC),
> <[EMAIL PROTECTED]> wrote:
>
> >In rec.photo.equipment.medium-format Mark Stephen
<[EMAIL PROTECTED]> wrote:
> >: I just picked up a Vivitar 283 strobe to use with my Yashicamat 124G
> >: and have a couple of questions.
>
> We have a pair of 285HV's.   I also have a question about the 283 and
> particularly the 285HV Vivitars:
>
> Anyone know or measured the guide numbers for the Manual settings (M,
> 1/2, 1/4,1/16)  with ISO100 @ 10ft.  (or other distances, ISOs?)
>
> The manual isn't helpful. Only has guide numbers for the different
> reflector settings.
>
>
>
>