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Re: [OM] Blood moon

Subject: Re: [OM] Blood moon
From: bj@xxxxxxxxxxxxxx
Date: Sat, 11 Oct 2014 02:34:28 +1300
Chuck wrote
Message: 2; 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
.................
Thanks for that.

Admittedly, this moon (below) is one of the images taken 
when it was rather closer to earth. May 2012.
http://zone-10.com/tope2/main.php?g2_itemId=14681

Also taken with the Zuiko 300/4.5 at f/11
Save the image and enlarge it with FS; you should find 
the degree of detail is quite nice.
Part of the difference is the direction of the illuminating 
light; in THIS image it is good side light which picks out 
surface details. In the case of the recent blood moon - no 
such benefits were available; dull frontal lighting, and not 
much of that either, which required me to make 
progressively large changes to the exposure parameters 
as the moon became less and less visible..

Brian


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