Venus transit

The June 8, 2004 Transit of Venus
from Tabriz - Iran

Technical infos
Optic :	Canon photographic lens EF 400 mm f/5.6 L + Canon EF 2x II (equivalent focal length of 800 mm at f/11)
Camera :	Canon EOS 10D ( raw CRW files)
Filter :	Baader Astrosolar ND 5.0
Mount :	Tripod
Location :	University of Tabriz - Iran
Exposure :	1/180 sec at ISO100 (electric remote control)
Processing :	Raw decoding, flat-field, stacking and wavelet processing in Iris 4.16

A minimalist setup (note the Tabriz city in the foreground)

Some view of the transit...
(image size is reduced by a factor two - click on the images for see original format)

5H27 UT

5H38 UT

6H58 UT

The image quality of the couple Canon EF 400 mm 1:5.6 L + Canon Extender EF 2x II

Stack of three individual unmanipulated images and simple mean of red, green and bleue channel layer (original size scale). The Bayer RAW image is converted to a gray level image with the gradient interpolation method of Iris software. 6H58 UT image.

The same image after a slight wavelet filtering (wavelet coefficient under Iris: 2.4, 1.3, 1.0, 1.0, 1.0). Sun granulation is clearly visible.

Part of the sun surfaces. Left, Canon EOS 10D + Canon EF 400 mm (scaled by a factor two - spline interpolation). Right Canon EOS 10D + Canon EF 400 mm + Canon Extender 2x. No processing is applied to this images. The resolution gain given by the Canon Extender is evident (more favorable sampling).
Click here for download a raw image sample (CRW file - size: 4.6 Mb) - Click here for download a debayerized unprocessed image sample (FITS file - size: 2.1 Mb)

Possible detection of the atmospheric ring around 5H34 UT (the ring is caused by sunlight refracted towards us by the atmosphere of the planet). Stack of 9 images and the result is scaled by a factor two. At left the contrast has been changed to show this elusive aureole outlining the disk of Venus. At right, a vertical gradient of one pixel is applied (bas-relief effect).