For: Joao Varandas MARQUES

[karabog@xxxxxxxxxxxxx (Bogdan KARASEK)]

Hi,

The note I sent you came back because the system could not find you address,
so I am sending it to the list in the hope that you will pick it up.

>Hi,
>I=B4m a member of the Infrared photography list.
>I=B4m asking this to you outside the list
> because of your last post........"I know that you have to bracket your
>shots on either side but what E.I. do you use as a starting point?"
>I don=B4t understand the meaning of "bracket"!!=20
>And it seems you do  :)
>could you give some help here?
>Sorry to ask this apart of the list... but it=B4s probably a stupid=
 question
>to post ;)
>
>Thanks in advance
>
>
>Jo=E3o Varandas Marques
>Parede - PORTUGAL
>
>janeca@xxxxx
>
>http://www3.telepac.pt/bira/photos/fragmentos.html   (Photo Homepage)
>http://www3.telepac.pt/bira/haine/    (Band Homepage)
>
>PGP key available on request ;)
>
>
Hi,

I don't think that it was a stupid question to ask.  On the contrary, it
shows that there was some arrogance on my part in assuming that everybody
outside the North American uses the same vocabulary/slang. =20

I'll try to explain the term "bracketing" with an example for starters:

Let us assume that my lightmeter is set at ISO 25, thereby giving me an
exposure value of 1/250s at f.8. I can now take my picture exposed at 1/250s
at f.8 and then, I can bracket that exposure by taking that picture at
1/250s at f.5.6 and f.11 or I can bracket by keeping the aperture opening
constant, f.8, and bracketing with the speed, 1/500 and 1/125s.

In other words, you are also taking a picture with exposure values on each
side (bracket) of your main exposure value.

The reason for doing this is that sometimes the meter can be fooled by the
lighting conditions and this is just a guarantee in case something goes
wrong and the main exposure value and picture are all wrong.  It's better to
have wasted two negatives then having to go back and redo the whole shoot,
if it is at all possible.  Bracketing is especially useful with difficult
lighting conditions, such as back lighting, where the light is coming from
behind the head of the person you are photographing. Unless you are very
careful, your lightmeter will give a reading for the light and not the
person's face, resulting in a picture where the person's face is completely
dark and the rest of the picture is normal.  So, just to be sure, you
bracket your shot.  It's a way of compensating when you aren't sure.

With infrared film, it is especially difficult to get an accurate reading
because you cannot see what the meter is reading, so you bracket your
exposures.  Some people have told me that they do two exposures on each side
of the main exposure, just to be sure.

example:

bracket  bracket   main   bracket  bracket
  f.4     f.5.6     f.8     f.11     f.16

OR

1/1000   1/500      1/250   1/125   1/60


Anyway, this is the general idea. If this is still unclear, then don't
hesitate to e-mail me about further explanations or any other stuff you
don't understand.

=20

  Regards
        =20
         Bogdan=20
                             karabog@xxxxxxx
         Montreal
         Quebec
         CANADA


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Topic No. 3