Landon Noll's target field and 2 cameras

Coordinating Eclipse Observations

As previously stated:

The following image shows my target field of view relative to the Sun during the 29 March 2006 Eclipse 80 km south of the Jalu Oasis in Libya near 28º17’53.5”N (28.2982ºN) - 21º34’10.9”E (21.5697ºE):

Landon Noll's 2006 eclipse target zone 

The above chart shows stars down to the 12th magnitude.  (A 12th magnitude Vulcanoid could be between 3.5km and 10km in diameter).  The dashed red line running through the Sun/Moon and the center of the rectangle is the ecliptici.  Zenithi is up.  The VEq red plus marks the Vernal equinox: the place where the Ecliptic and the Equator (0 deg declination) meet.  The magnitude of the brighter stars are marked by 2 or 3 digit numbers.  To get the visual magnitude, divide the number by 10.

The rectangle above is 6.4º wide and 4.3º high.  The edge of the box that is closest to the Sun is 4.1° from the center of the Sun's disk.  The far edge of the box is 10.5° from the center of the Sun.

Here is information about my camera setup:

I will shoot the above field of view with a Canon EOS 20Da Red/almost-near-IR sensitive camera and a Canon EF 200mm f/2.8L II USM lens operating at f/2.8.  I will be using a B+W 72mm Infracolor Orange 099 Infrared Glass Filter to filter out light shorter than 600 nm.

I am also planning to shoot with a Canon EOS-1D Mark II N in the visible wavelengths and a Canon EF 70-300mm f/4.5-5.6 DO IS USM lens operating at f/5.6.  I will be using a standard B+W 58mm UV Haze 010 filter on this camera.

The lens will be zoomed to about 235mm to get a slightly larger (~4%) field of view.

Both cameras will be mounted on a Orion Sirius EQ-G GoTo Mount, setup and polar aligned during the previous evening.  Both cameras will have noise reduction turned off.  Both lenses will be on manual focus.

Both cameras will be automatically driven with a Canon TC-80N3 Timer Remote Controller device.  The timer will drive the cameras by taking a sequence of "N second" exposures separated by an internal 1 second.  The 1 second internal is forced due to the way the TC-80N3 operates, unfortunately.  I will start both cameras about 5 minuts before 2nd contact (start of totality) and let them run a few minutes after 3rd contact (end of totality). 

BTW: It is my practice to try and gain as much directly human sensory experience from the eclipse as I can. I want to be fully engaged to see, hear, feel, smell etc. as much as possible during the eclipse.  Thus I never operate with equipment during totality.  My eclipse experiments are designed to run by themselves so that I directly experience as much as I can from the event. 

To help calibrate the images and because the camera will operate during totalty with noise reduction off, I will take a few dark frame exposures with noise reduction on followed by a few exposures taken with noise reduction off before the start  and after the end of the exposure sequence.

I plan to establish the "N second" optimal exposure value by performing a zenith test during the next 2-3 weeks, weather permitting.    Because we are near the solar minimum I expect to see a large, bright and well formed corona.  Because of high altitude dust that is frequenttly found over the Sahara, I expect a somewhat greater than average amount of light scattering.  Both of these might produce a somewhat brighter than average sky during totality.  On the other hand 4m 3s is a longer than average eclipse, and we will be obseving near local noon where the moon's shadow will be nice and round offering a optimal shadow during the middle of totality.  For these reasons I believe that a zenith test where the Sun's disk is 5.4° below the ideal horizoni might serve as a good model for the 2006 totality conditions.  (The typical eclipse is equiavalent to about 5.5° below the ideal horizon.)

I have not determined an optimal ISO setting for either camera. 

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Submitted by chongo on Mon, 2006-03-20 09:04.

Using the XEphem tool for the location 28º17’53.5”N (28.2982ºN) - 21º34’10.9”E (21.5697ºE), the minimum separation between the Sun and Moon occurs at 10:29:30 UTC (0º0'07" separation).

The 10:29:30 UTC value differs from the previous value that I used (10:28:50.5 UTC).  That 39.5 second difference does not matter very much.  Still just to check my calculations, here is the target location details:

If my calculations are correct, the center of the Sun at the middle of the eclipse (10:29:30 UTC) will be about RA 00:31:16.7s Dec +3:22:28.0.  In order to place the center of the right-hand edge (of the 6.4º wide field of view) at 10.5º from the Sun, the center of my field of view needs 7.3º from the center of the Sun.  To maximize the chance ti image a Vulcanoid, this 7.3º from the center of the Sun needs to be along the ecliptici.  I have chosen to image on the west / right-hand side of the Sun.  This means that the center of my field of view will need to be near RA 00:04:26.9 Dec +00:29:00.0.

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Submitted by chongo on Sun, 2006-02-26 03:22.

My experience with normal landscape photography suggests that The 1D Mark II N can operate at ISO 800 without too much noise.  The 20Da might be as good as the 1D Mark II N according to some signal-to-noise measurements I have seen.

When I view the Art of Seeing Noise vs ISO test, the ISO 200 image looks best for the 20D.  The OutbackPhoto ISO set suggests that ISO 100 is best for the 20D.  This seems suggest that ISO 100 or ISO 200 might be best for the 20Da. Moreover, with multi-second exposure times with noise reduction turned off, I might be better off shooting towards the ISO 100 end of the scale anyway.

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Submitted by chongo on Mon, 2006-03-20 08:11.

I plan to use both of my cameras at ISO 100.  While ISO 200 does not increase the noise by much, it may be safer to use ISO 100 because it is the lowest possible noise setting.

 

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Submitted by chongo on Sun, 2006-02-26 02:08.

My guess is that the "N seconds" in the above article will be between 4 and 20 seconds.  I would not be surprised to find that it will be about 10 seconds for the 20Da.

To reduce the chance of one camera's shutter vibration impacting the image of the other, I would prefer to have both cameras taking exposures of the same duration.

The 20Da's 099 filter, by blocking wavelengths shorter than 600nm will reduce noise due to sky glow.  However, if the 1D Mark II N camera images over the most of visible wavelengths, then it will collect more light for the same exposure time even when it is using twice the f-stop.  Therefore I may need to boost the 1D Mark II N lens f-stop above f/5.6, lower the ISO, or I may need to use a filter of some kind.

BTW: If the 20Da must operate at ISO 100, then the 1D Mark II N cannot use a lower ISO setting (ISO 50 degrades image quality).

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Submitted by chongo on Mon, 2006-03-20 08:07.

I plan to use a Canon EF 200mm f/2.8L II USM lens on the Canon EOS-1D Mark II N as well as the Canon EOS 20Da.

Also my tests show that the B+W 72mm Infracolor Orange 099 Infrared Glass Filter on the Canon EOS 20Da increases exposure time by 40% over the clear B+W 58mm UV Haze 010 filter on the Canon EOS-1D Mark II N.  For example a 10 second exposure on the Canon EOS-1D Mark II N with the UV Haze (clear) filteris the same as a 16 2/3 second exposure on the Canon EOS 20Da with the 099 orange/red/IR filter.

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