Ström (strom_photo@usa.net)
Wed, 19 May 1999 22:17:31 -0400 (EDT)
In another posting I described my handling of exposure, development and
printing of negatives from indoor and outdoor photography. I mentioned in
passing that I use a Hasselblad camera. I did not mention that I use the same
spot meter in both circumstances, which is a Minota Flash Metre IV. It is
effective for spot metering reflective light in both flash and incident
settings. I have checked it against camera meters and incident meters
(Sekonic and Minolta). The Hasselblad camera I use requires lenses with copal
(leaf) shutters. The fastest shutter speed is 1/500 second and the slowest
(camera controlled) is 1 sec. In studio I always use 1/125, whether handheld
or tripod. I vary the strobe power to accommodate this. For outdoor
photography I always use a tripod and vary the shutter/aperature according to
the metered light, film speed, and depth of field. I do not work in the realm
that requires compensation for reciprocity error. The use of a strobe (in my
studio a 2400 watt strobe is sufficient for my work) demonstrates that indeed
shutter speed is usually irrelevant. There is one exception, however, that
should be noted. When using a leaf shutter, the strobe in use my limit the
shutter speed. For example, the strobe synchronization may not permit a
shutter speed of let us say 1/500. The fastest shutter may only be 1/250 or
even 1/125. This can be easily measured with a good spot meter. Since I
invariably use 1/125 as my shutter speed, I can rely on the relationship
between the strobe power setting, reflective spot meter, and the camera's
aperature. It is not wise to vary a shutter speed while in the studio--it
should be kept the same for all work. Outdoors is another matter and depth of
field and lighting conditions will dictate what is required.
Ström
Date:
Wed, 19 May 1999 18:47:36 -0700
From:
Richard Knoppow <dickburk@ix.netcom.com> | Add to Address Book |
Block address
Subject:
Re: Indoors film speed
To:
alt-photo-process-l@sask.usask.ca
Reply-to:
alt-photo-process-l@sask.usask.ca
At 05:59 PM 5/19/99 -0700, you wrote:
>John Erbes wrote:
>>
>> At 11:39 AM 5/19/99 -0700, Gary Miller wrote:
>> >Speaking of the difference of shooting outdoors as opposed to
shooting in
>> >the studio, why are the outdoors negatives so much more dense. If
I am
>> >taking a meter reading both inside and outside shouldn't the
negatives
>> >ultimately be the same density if I am rating the film at the same
ASA. I
>> >know that Carl has mentioned the difference between using a spot
meter
>> >reading outdoors as opposed to a flash meter reading in the studio.
But
>> >shouldn't it all be relative? My shoots from outside are much more
dense and
>> >stained than my studio shots.
>>
>> Gary,
>> It's my understanding that film speeds are slower indoors typically
by a
>> stop or so as compared to their rated outdoor speed. I don't know
why,
>> but I'm sure that someone on the list will explain.
>>
>> John Erbes
>
>In THE BOOK OF PYRO by G. Hutchings on page 66 he discusses the
>increased densities of the negs. due to the internal flare bouncing
off
>the inside of the camera. The increase is, according to his testing,1
>stop in added exposure.
>
This just can not be made as a general statement. First, the amount
of
flare is going to be dependent on the construction of the camera. Some
cameras have excellent flare baffling, post 1954 Roleiflex's and
Rolleicords for instance. Secondly, flare affects mostly the toe
exposure
and has little effect on the overall density of a negative. The
statement
also assumes that interior lighting is going to be more flare free than
exterior lighting. Perhaps true for carful studio lighting but not as a
general statement.
This is simply not the cause of a consistent large difference in the
exposure of negatives made under two conditions.
One possible cause, if the interior lighting is via strobe is
inaccurate
shutter speed. For strobe the shutter speed has no effect in
controlling
exposure. It mearly has to open before the flash and shut after it. For
exposures with continuous light, as with daylight, the shutter is going
to
have a profound effect. Mechanical shutters are not exactly precision
instruments, especially old LF shutters. An Ilex, for instance, was
speced
for only +/- one stop when new, they can easily be a stop or more off
speed. Other large shutters are not much better.
About the only way you can tell is to use a shutter calibrator like
the
one available from Calumet. They are not expensive and will blow the
whistle on inaccurate or inconsistent shutters.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
____________________________________________________________________
Get free e-mail and a permanent address at http://www.amexmail.com/?A=1
This archive was generated by hypermail 2.0b3 on Thu Oct 28 1999 - 21:39:34