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Re: [OM] Blood moon

Subject: Re: [OM] Blood moon
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Thu, 09 Oct 2014 08:05:23 -0400
I'd like to offer some technical advice for the next try.

At 300mm the image size on the sensor is only 2.75mm. That means you've had to do a fairly severe crop which is showing some noise at ISO 400. Also at 300mm you're shooting at a 600mm 35mm equivalent. The 35mm formula for maximum exposure time of the moon without showing motion blur is 600 / (Focal Length). So with a 1 second exposure time you are exactly at the maximum and so pushing the limits. You've also made the exposure at f/11. That is well into diffraction territory for a 4/3 sensor. For ordinary photography maybe not noticeable. But for high magnification (severe crop) it might be.

Taken all this together I would suggest that you take your next shot using an aperture of f/5.6. Under optimal conditions f/11 is actually the best performing aperture for the 300/4.5 but the performance at f/5.6 is not much worse. Shooting at f/5.6 would allow you to split the exposure difference between ISO and shutter speed and gain 1 stop on each. You could have used f/5.6, ISO 200 and 1/2 second. Also, at f/5.6 you'd have a brighter image for focusing.

There are two more total eclipses coming up next year in April and September so maybe you'll get another couple of chances. Until then you can practice on the non-eclipsed moon which should be a bit easier.
<http://en.wikipedia.org/wiki/List_of_21st-century_lunar_eclipses>

Chuck Norcutt


On 10/8/2014 5:05 PM, bj@xxxxxxxxxxxxxx wrote:
Hi all,
The best of a bad lot.
http://zone-10.com/tope2/main.php?g2_itemId=14672

Cheers, Brian

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