Re: analemma

OG wrote:
"Mike" <mike@xxxxxxxxx> wrote in message news:ptZfh.66475$rv4.64543@xxxxxxxxxxx

How does one go about photoing the analemma over a year? Do you combine 12 -20 pics? You probably
need a sun filter too otherwise too much glare. How is it done?

The current master of the photographic Analemma is probably Anthony Ayiomamitis

http://www.perseus.gr/Astro-Solar-Analemma.htm



Mike/Owen,

I describe the technique here: http://www.perseus.gr/Astro-Tips-Analemma.htm . I should point out that "12-20 pics" is way too few and something around 40 exposures are required.

The three most critical exposures are the extremes of the analemma which occur on the solstices and the cross-over point which occurs around April 12-13 and/or Aug 30-31.

I suggest you decide which analemma you wish to pursue (ie. what time of the day is best for you) and then to identify the range of the sun in azimuth and altitude at that time for one complete year ... this will help you identify which lens(es) are suitable by providing a sufficient field of view to accomodate the complete range of movement.

I also suggest that you use Baader's ND5.0 visual filter and proceed with a few test exposures to make sure your focus is spot on (use tape to ensure the barrel of the lens does not rotate for shift and/or focal length if using a zoom) and, more importantly, the exposure is appropriate (ex. with ISO 100, you probably want somethign like 1/125 sec which is about three stops OVER-exposed so that the sun will be captured adequately when it is low in the sky).

Since the sun changes its azimuth and altitude by varying amounts during the year, BE PREPARED for periods when you will be taking an exposure every 4-5 days as well as other periods when your exposures will be 2-3 weeks apart.

Anthony.
.

Relevant Pages

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