[Leica] Re: [Lieca] Infinity / Jim & Aurora Borealis

[Jim Brick <jim@brick.org>]

At 09:58 PM 12/17/97 +0100, you wrote:
>Let's suppose your idea is correct, Jim: At which distance would 
>you adjust the 1.4/35 asph M Summilux at f 1.4, if you want to 
>take pictures of the stars ? I don't want to upset you, I'm asking 
>seriously, because of Tom Kline's yesterday question (pix of the 
>Aurora Borealis). I wouldn't know anything else, than the infinity
>symbol - even if the object of desire is 2000 lightyears from home :)
>
>Alf

Alf,

It's my feeling that with a subject like the Aurora, there's nothing that
is really in "focus" anyway. It's not an object (like the moon), it's  a
luminous phenomenon that consists of streamers or arches of light appearing
in the upper atmosphere of a planet's magnetic polar regions, and is caused
by the emission of light from atoms excited by electrons accelerated along
the planet's magnetic field lines. This, in my opinion, will look the same
on film with a 24mm or 35mm lens, wide open, and set on infinity or just
backed off from infinity. It's not going to be tack sharp, because it isn't
a sharp subject. Since the Aurora appears "in the earth's atmosphere", it's
minimum distance is 40 miles and maximum is 600 miles.

A point of interest, the Space Shuttle flies at around 190 miles up. It,
therefore, can fly through the Aurora.

How about the moon. Take a long lens and focus on the moon. You can focus
past the moon. The moon is about 238,900 miles away from the earth.

An object 2000 lightyears away is, at best, a tiny tiny pin point on the
film. Perhaps smaller than the circle of confusion. Remember, we are
talking about regular over the counter Leica lenses, not telescopes. I have
not experimented with stars. I did photograph Hale-Bopp. My best shots were
at about 70mm and 135mm (70-180 zoom) and my 350 Telyt, all wide open, and
I indeed had to focus on the comet. At the infinity stop, it was not in
sharp focus, that is, I could detect a difference.

Please realize that all of my discussion about infinity and lenses is my
humble opinion. This is the way I see it. And it has proven to be correct,
for me, for a good many years. So I will not change my habits, even if the
scientists or other worldly scholars prove that infinity is closer than we
thought. The only fly in the ointment might be a lens designed, knowing
that there is no such thing as infinity, with the infinity stop set so that
at maximum aperture, everything beyond wherever the stop is set, will fall
within the circle of confusion and be considered sharp. But we are
splitting hairs here.

So, for me, every photograph I take, I first think "depth of field".
Knowing what I actually want in focus, will guide me as to where I focus.
Remember the 1/3 - 2/3 rule. This is why R Leicas and View cameras are my
main tools. As I said before, I never set the lens on the infinity stop. My
training prohibits it. I break out in a cold sweat thinking about it.

If anyone wants to see a really great picture of Hale-Bopp AND the Aurora
Borealis in the same photograph, go to:


http://www.alaskaone.com/didier/index4-1.htm

Jim