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From: MikeWhy on 19 Jan 2010 14:18
"J. Clarke" <jclarke.usenet(a)cox.net> wrote in message
>>> On Sat, 16 Jan 2010 05:04:40 -0800, Charles Packer wrote:
>>>> For the three scenes I'm shooting with a tripod at a fixed location
>>>> [...] I can use all the speed I can get for the low light
>>>> conditions I'm shooting in.
>>> Why do you need all the speed you can get, if you're using a tripod?
>> I shoot before dawn on clear days (to be free of shadow), a
>> little later on cloudy days. My shutter speed is typically
>> around 1/15 second, but on many days I need to go down as
>> to 1/8 or 1/6. On cloudy days when I can shoot at 9 AM I
>> can use 1/30. At these speeds I have to accept any blur
>> caused by wind moving the tree branches, but a plus of
>> shooting early in the morning is that the air is usually still.
>> I'm using an ISO setting of 400. I would worry about
>> noise with ISO any higher. This is not normal photography!
>> I intentionally "blow" the sky because I'm going to crop
>> it out anyway. The trees are way dimmer than the sky and
>> I try to get the tree part of the histogram as high on the
>> x-axis as possible.
> It seems to me that what you would in an ideal world like to be able to do
> is shoot at about 1/focal length (the "rule of thumb" for hand-holding
> non-IS lenses--in the absence of more information on subject motion it
> a reasonable place to start) in your worst-case conditions.
> So let's assume that you're at the 25mm end of your stated range. So you
> want to shoot at 1/25 and you're now shooting at 1/6. That's close enough
> to 2 stops to make no never mind.
> So how fast a lens would you need? 2 stops faster than f/3.5 is f/1.8.
It would take pretty expensive glass to get good sharpness wide open.
Depending on focal length, the depth of field might not be sufficient.
Stopping down a few solves a lot of the ills, but of course needs a longer
exposure to compensate. Video has the limitation that the shutter speed
can't exceed the frame rate. Shooting from a stable tripod removes much of
the shutter speed constraints, and leaves only the more subjective motion
blur requirement. It's a tough call. Anyway, it still comes back to f/1.8
even when available might be too soft on image quality.
I did something similar a few years ago with a camcorder looking out a
window in a spare bedroom. It sat undisturbed for 45 days, waking itself
every hour to shoot 2 seconds of video. Two seconds was about right to make
sense of the random activities it captured: the neighbor walking his dogs,
joggers on the footpath, the wind as evidenced in waves and trees, and the
quality of light as the day passed and weather systems moved through. I will
say, though, even after editing out the completely dark night shots, it was
still agony to watch all the way through. That tape spanned the spring
equinox, averaging about 30 seconds of tape per day -- 15 hours of daylight
at 2 seconds every hour. I had 45 days, or about 20 minutes of video.
Good luck on your project.
From: Wolfgang Weisselberg on 20 Jan 2010 16:24
J. Clarke <jclarke.usenet(a)cox.net> wrote:
> same ballpark at the T1i, and there is a 14-35 f/2.0 lens for it (the
> Olympus uses a smaller sensor than the Nikon and Canon, so that lens on an
> Olympus body gives the same field of view more or less as a 28-70 on a Nikon
> or Canon).
Only on full frame. The OP's using a 1.6x crop frame camera, so
the 14-35 would give the same viewing angle as 17.5-43.75mm on