Contacter l'auteur / Contact the author

Recherche dans ce site / Search in this site



The solar analemma

The analemma of 10h UT over Zeus' temple, Athens.

Text and pictures by Anthony AYIOMAMITIS

Problems and Issues (IV)

My initial expectations with respect to potential problems and issues centered on the weather. I have always felt that skies in Greece are sufficiently clear and stable to challenge the infamous clear skies of Arizona and this was something that I would formally reconfirm during the course of this project which lasted nearly two years (see Table 3).

However, I soon discovered that my only real challenge was the accidental tripping of the film advance lever as it repeatedly did ruin a number of analemmas (fortunately early during the shooting schedule of the first run causing restarts up to nearly three months later than the original start date).

As a key consideration and objective of this twelve-month exercise was to generate Figure 14 using actual analemmas - in lieu of the theoretical figure in the di Cicco article (S&T, Mar/2000, pg 136) - I sought to not only use the same physical lens (Canon FD 24 mm f/2.8) for all 473 images (11 analemmas with 43 images per analemma) but also the same camera bodies that were fully compatible with this lens. My two personal Canon A-1 series cameras have a specific switch for multi-exposures that make this exercise a no-brainer. 

However, the Canon AE-1 series camera which is also fully compatible with the FD series of lenses does not have such a feature and the interested photographer must resort to the unorthodox technique of tripping the rewind button at the camera base plate and then advancing the film lever.

For some bodies of the Canon AE-1, there is enough extra friction in the mechanism to move the film a bit even though the rewind button has been pushed - once the film moves, however slightly, the rewind button will pop back out and re-engage the advance and, as a result, render this backdoor method useless. 

Regrettably, it is this unfortunate scenario that repeatedly ruined a number of my analemmas during the first two to three months of this project. For the three "problem" Canon AE-1's, I would soon discover that I would have to trip and hold in place firmly the rewind button at the camera base plate using a small flat screwdriver while simultaneously advancing the film lever. With a fourth Canon AE-1 body (09:00:00-10:00:00 UT analemmas), I would simply totally forget the above modus operandi on one occasion (Sep 26/01) and ruin yet another double analemma in progress losing four weeks worth of imaging.

The analemma of 10:28:16 UT over Parthenon, Athens.

The most problematic Canon AE-1 body was later purposely reassigned to a single analemma (15:00:00 UT) so as to minimize the number of desired multi-exposures from 86 (double analemma) to 43 (single analemma). 

Nevertheless, imaging with this camera was restarted on five different occasions and, on the fifth and final restart, I did consider prematurely retiring this camera body by personally "launching" it into satellite orbit and pursuing a replacement immediately thereafter,  thus finally terminating this chronic and incessant "Greek tragedy".  

After frequent aborted starts, all involving my newly acquired Canon AE-1 camera bodies and with sufficient lost multi-exposures to assemble the equivalent of nearly three analemmas, I prepared a checklist (Table 4) so as to eliminate, where possible, any future and further additional delays or accidents wherever possible. 

Readers interested in pursuing analemmas of their own using the Canon A series cameras should certainly select the Canon A-1 as its built-in multi-exposure mode is ideally suited for this project.

In contrast, each of the five Canon AE-1 bodies led to at least two restarts due to a failure in the unorthodox method for taking multi-exposures mentioned above and which painfully reminded me of the classic ancient Greek story about the punishment Hades handed out to Sisyphus to roll a block of stone up against a very steep hill which would eventually roll back down as he reached the top; Sisyphus would have to restart all over again and would keep doing so for eternity!  

Nevertheless, my heart would stop each and every time I would engage the film advance lever on my various Canon A-1 and AE-1 cameras as one accidental true film advance and the complete analemma to-date (or two analemmas if imaging a multiple analemma which I eventually did successfully accomplish using four of the cameras) is rendered incomplete and, therefore, meaningless ! Of course, this cardiac arrhythmia would be something that would progressively get worse and worse with each analemma that would progress further and further between accidental film advances.  

The analemma of 11h UT over Athens.

On a related note, the field of view of my Canon FD 24mm f/2.8 lens (53 x 74 arc coverage in landscape mode) is such that it was possible to attempt a double analemma photo. Very careful placement of the permanent mount with respect to azimuth and even greater care in the determination of the altitude for the camera mount was exercised due to the extremely little room left for error. 

Using the figures in Table 1 for example, the range in altitude for the 09:00:00-10:00:00 UT double analemma (48.8) is such that an error less than 10% is available or, practically, less than 5% in either direction. The tolerance for error was even less for the 11:00:00-12:00:00 UT analemma where the range in altitude was 49.3. 

A blessing in disguise is the fact that if an error does occur in the proper placement of the camera and/or its permanent mount with respect to altitude and azimuth respectively, one complete analemma should still be produced once the exercise has been completed.

Aside from a camera with the ability to properly take multiple exposures, an appropriate wide-angle lens and a shutter release cable, it is also advisable that a right angle finder (such as the Canon Angle Finder B) be used to assist in properly framing the analemma (vis a vis the lack of available tolerance for error, for example, if imaging a double analemma) and for monitoring the progress of the imaging, for five of the eleven analemmas in this exercise had a maximum altitude in excess of 65.

Something that was overlooked but became obvious after the fact is the camera straps which hang freely while one is carrying the camera with mount in his/her hand. These straps have a tendency to lock onto objects which protrude and, hence, destroy the permanent and fixed position on their mount using silicon. This is something that occurred not once but twice during the first marathon attempt and was resolved during the second marathon attempt by their complete removal from the strap lugs.

The analemma of 12h UT over the Temple of Aphaia (490-480 BC), Athens.

On one occasion, the accidental locking between camera strap and protruding object was so vigorous that the camera was completely dislodged from the constructed mount (another restart!).  

A subtle consideration also worthy of mention is the change in time each spring and fall where clocks are adjusted backward or forward by one hour. I have (almost) consistently worked in UT format during the 21-months duration of this exercise so as to avoid any confusion and, more importantly, yet another set of restarts.

This did not prevent me, however, during late April/2002 from shooting an hour early the analemmas at 06:00:00 UT and 07:00:00 UT when my mind was working with the local time in effect prior to the time change a few weeks earlier. This is something that would occur once again in mid-October/2002 when the analemma at 09:00:00 UT was taken with the camera for the 08:00:00 UT analemma due to a similar confusion. 

These three images of the sun have been removed digitally and, fortunately, did not adversely affect the final images for these analemmas as a result of overlapping solar disks. The analemma of 07:00:00 UT and 08:00:00 UT were however restarted in 2003 and these are these last images that are reproduced on this page.

Last chapter

The weather factor

Page 1 - 2 - 3 - 4 - 5 -

Back to:


Copyright & FAQ