Sorry to open this again, but I can?t understand something Michael said.
In his article ?Lunar Eclipse? http://www.luminous-landscape.com/location...ipse-2003.shtml
"I wanted greater magnification and also needed a higher ISO, and so I switched to my new Canon 10D along with a Canon 2X extender on the 500mm f/4 lens. This gave me an apparent focal length of 1,600mm at f/8, and more importantly I was able to use a coincidently matching ISO of 1600."
On the apparent focal length of 1600 mm, the same lens on the 1Ds would have had a focal length of 1000 mm and would have produced a wider field of view. However, if that image was cropped to the same field of view as the 10D, would it be any different.
I thought that there was no conceptual difference, so there would be no advantage to use the 10D, other than to save the cropping.
If so, is Michael?s statement accurate?
It doesn?t work out to 1.6 exactly when I do the simple arithmetic. The 10D produces an image of 3072 x 2048 pixels. The 1Ds produces an image of 4064 x 2704 pixels. The 1Ds image size is that of the 10D divided by 1.32. If you cropped the 1Ds image based on a 1.6 factor, it would become 2540 x 1690 pixels. I don?t know what conclusion to draw from these specifics.
Any enlightenment would be appreciated.