Re: [KOML] Aerials

[Harris Goldstein <hgoldstein@ibm.net>]

It is my understanding that some lenses focus past infinity (optical experts -
feel free to weigh in and confirm or deny).  Since the KO focusing is done by
the camera body, not the lens, you have to validate your camera/lens.  I did it
on land on a tripod - it was fine either by luck or design.

Even if your 1000ft AGL (above ground level), if you're shooting obliques
(which you probably are) the distance to your primary subject is greater than
1,000ft.  At a 45deg angle, it will be about 1400 ft.  While your subject is on
an angled plane, with foreground closer than background, the depth of field
should accommodate (even with the 180mm).  But the smaller the f/stop (I tried
to keep it at no greater than f/8, and preferably f/11) the better.

Vibration can usually be dealt with by using a fast 1/500 shutter speed and
isolating yourself as much as possible from the airframe.  This last point is
critical.  Your arms cannot be touching; your butt should be the only
connection between the film plane and the engine.

The biggest problem is atmospheric haze.  However bad it looks through the eye,
it looks worse through the lens.  A good UV filter helps some, but some days
you just can't shoot.  And you can't shoot into the sun.  If shooting color, a
film with high contrast helps as well.

Obviously, when you combine small f-stops and fast shutter speeds, you need
fast film (ISO 400).  Grain may be objectionable, but lack of sharpness is much
more so.  This brings us back to the need for a large negative (assuming you're
using all/most of the negative).

Harris


John J Stafford wrote:

> > So, I should focus at infinity? I tried that but if I remember the
> > finder showed that I was out of focus. I will try again and report back.
>
> My experience with aerial photography includes the Big Stuff: USAF recon
> RB66 and Voodo RF101 airplanes in the sixties. Sure, we used monsterous
> hardware (like 9" by 180 fool rolls of film, shot in stereo), which doesn't
> relate to our work, but two other things did. First, the motion of the
> focal plane and film relative to the direction of the aircraft is
> important. Our take on this is to either not use FP shutters (which the KO
> does not), or to be certain that the FP shutter travels in the same
> direction. Since we don't have the option of a film traveling across the
> shutter, use the very highest shutter speed you can. The other point,
> pertinent here, is that just because you are at 1000 feet, does NOT mean
> that the ground is at infinity. 1000 feet is really pretty low (compared to
> my experience), and bare in mind that you are shooting at a relatively flat
> target - one that really shows when you haven't perfect focus.  Dunno how
> well the KO accomdates 'infinity', especially with its longer (180mm) lens
> (which is wonderful on land.)
>
> I have several aquaintences who shoot aerials, and unfortunately the best
> of them is not very good. It seems they all have problems first with focus,
> steady cameras and fast shutter speeds and second, with LIGHT. They just
> don't get it.