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Re: (meteorobs) Daylight Leonid Meteor Strom

In a message dated 98-11-01 18:10:59 EST, you write:

Rob<< 
 Perhaps I've missed the point here, but why would anyone use a fast film
 in daylight.  With 100 ISO film at f3.5, the daylight sky here gives a
 1/500 sec exposure.  This is much faster than necessary to freeze a
 fireball.  The slower films will give a much improved grain.  There is
 probably no need to have any depth of field either, so closing the lens
 down from full aperture would only be required if the image quality is
 poor at full aperture.  At f2.0 you could easily use 25 ISO film without
 any blurring of the fireball or handshake.
  >>

Rob, I havne't thought it all thru just yet, but my photographic instincts
tells me that I would want a faster film than ISO 100. Since I'm using black
and white, the next fastest speed would be ISO 400. I consider Plus-X with an
ISO of 125 to be essentially 100. I plan on using two camera's. One will have
a 135mm lens and the other with my 200mm. I'll play accordingly to activity at
the time. Might use both alternately?  If I used a 50 mm lens, any fireballs
that show up might appear as scratches or a small black speck on the negative.
There will be no bright trailing as in night time meteor photography. I also
want to have some high contrast if at all possible for anything in the sky to
show up. Thus I plan on using a deep red filter with the 200mm f/3.5 and a red
filter with the 135mm f/2.8. I'm also considering the usage of a polarizer
with probably the 135mm. Since I don't have mega buck lenses, I will not have
the aperature wide open and will have to step down some so that the image may
come out a little sharper. The filter factor for the deep red filter is 16 and
the Red filter is 8. The polarizer factor is 2.5. If I had a film of 400 ISO,
I can expect to have a normal bright daylight shutter and f/stop setting at
around 1/500 sec at f/16 as a base to figure my exposures from.  I expect to
be moving the camera around quite rapidly. With a telephoto lens, movement
shows up quite easily from both ends....that is the movement from the camera
itself and the movement of the distant objects. A shutter speed of 1/125th may
be adequate, but I want a little insurance and chose to not go less than
1/250th sec. So if I start out with an exposure of 1/500th sec at f/16, let's
see what the filter factors might force me to do? A filter factor of 16 for
the Deep red filter would mean that I would have to multiply the exposure by
16 or open the aperature by 4 f/stops. Leaving the shutter at 1/500th sec I
would end up with an f/stop of either f/5.6 or f/4. For the 135mm with the Red
filter and filter factor of 8, I would end up with an f/stop of f/8 or f/11.
Now if I use the polarizer on the 135mm, I might have to open the aperature
another stop to around f/5.6 or f/8?  If I used film with an ISO setting of
100 and do the same for it with the same equipment above, I would end up with
a shutter speed of 1/125th sec at f/4 or f/2.8. I don't feel comfortable with
a shutter speed of 1/125th in this case nor a wide open aperature for my
telephoto. Now these settings would work probably for smaller lenses in the
range of 50mm I"m sure. Personally, now that I've walked thru it, I will stick
to black and white film with an ISO setting of 400. In my case I will most
likely use HP-5. Though T-max 400 probably will work just as well? 
George Zay