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Re: [OM] shutter speed

Subject: Re: [OM] shutter speed
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Mon, 21 Dec 2009 10:54:48 -0600
Now comes the really fun part.  Guessing the aperture and ISO.

Since we can safely conclude it was about 1/4000 and "Sunny 16" there is
another clue. The picture itself looks like it was shot pretty wide open
with most likely a 70-200 F2.8 wide-open or at most F4. The photographer
probably sought to maximize shutter speed so I was going to guess F2.8 as
the ragged, but soft Bokeh kinda suggests that lens at or near wide-open,
but needed just enough DoF to get the entire tripod in focus as well as
increasing quality a touch.

So, we we have 1/4000 at F4 in sunny-16 conditions. An equivalent exposure
is 1/250 at F16. Or inotherwords, if this was sunny-16 conditions, the ISO
would be approximately ISO 200. But, wait. The sun is lower, so it's not
mid-day, so it looks like Sunny-16 down two stops. The golden colors and the
direct lighting from behind the photographer gives me pause that Sunny 16
isn't valid. So, I need to slow my shutter speed down two stops or increase
ISO.

So, instead of ISO 200, 1/250 at F16, I'm guessing ISO 800, 1/250 at F16.
The equivalent exposure is therefore ISO 800, 1/4000 at F4.

However, the folded in bubbles in the bokeh highlights indicate an
aspherical lens shot wide-open, or worse yet, use of a teleconverter. But
it's probably a Nikon, so F4 could still be the aperture. When conspring
with a higher ISO, the bokeh tends to get a little more ragged looking.
Judging from the AoV, this is looking more like a 300mm shot, so the
photographer used a 1.4 teleconverter which doesn't actually give you the
bokeh of a 300mm lens, but more of a 200mm lens magnified.

My guess is ISO 800, 1/4000 at F2.8 with 1.4 teleconverter. Lens is the
70-200 F2.8 at or near the long-end.

Ok, back to work now.

AG
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