Well, this will be the last post in my lifetime on the transit of Venus in front of the sun. We have a couple of reader photographs of yesterday’s rare astronomical event.
The first comes from reader Pete, who calls our attention to his group of ten photos on his online album.
The photos were taken with Canon EOD 7D using a 70-200mm f/2.8 lens (at 200mm, obviously!) with a 2x teleconverter, yielding an 400mm effective focal length, or about a 13x zoom compared to a “standard” 30mm focal length for that body. I placed a 1000x (10-stop) neutral density filter on the lens, but even so had to use 1/8000s exposure at around f/16 for a reasonable exposure. Focus was manual using the LCD “live view” with 10x magnification to try to get as sharp an image as possible.Interestingly, for this purpose it was better to use the 7D over my newer and higher resolution EOD 5D Mk III body, because in spite of the higher total pixel count, fewer of the 5D3’s (larger) pixels would cover the image. This is generally true for astronomical subjects: higher pixel density in the sensor is more important that a high pixel count, as long as noise is kept under control.
‘The videos and images displayed here are constructed from several wavelengths of extreme ultraviolet light and a portion of the visible spectrum. The red colored sun is the 304 angstrom ultraviolet, the golden colored sun is 171 angstrom, the magenta sun is 1700 angstrom, and the orange sun is filtered visible light. 304 and 171 show the atmosphere of the sun, which does not appear in the visible part of the spectrum.