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Author Topic: 1.6 Magnifier Michael  (Read 1719 times)
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« on: June 21, 2003, 01:26:27 PM »
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I was reporting on the fact that I changed to the 10D because of its superior high ISO capability. I mentioned the effective focal length of this combination as a matter of interest, but I also mentioned that it is an "apparent" increase not real, as you've pointed out.

As for the cropping factor, different companies measure it differently. It can be measured by diagonal, linearly or based on area. The way Canon does it it's 1.6X

Michael
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Bruce Lewis
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« Reply #1 on: June 21, 2003, 12:19:26 PM »
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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 Michael said

"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.

Regards,

Bruce
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Rainer SLP
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« Reply #2 on: June 21, 2003, 01:58:39 PM »
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Apart from what Michael said, I would have done that too because of the resolution.

In which way you crop you image afterwards does not matter. In any case you have a higher resolution, pixels per mm or pixels per inch, on the 10D and I think for motifs like this is it to welcome.

EOS 10D 3072 x 2048 pixels, chip size 22.7mm x 15.1mm giving you a total of 135.3 pixels per mm or 3436 pixels per inch

EOS 1Ds 4064 x 2704 pixels, chip size 35.8mm x 23.8mm giving you a total of 113.5 pixels per mm or 2882 pixels per inch.

I was between choosing the 10D and the 1Ds and decided for the 1 Ds because of no factor, because I like my wide angle lenses like the 16-35mm for panoramas as well as the 15mm full frame fisheye.

If I would not like so much the wide angle photography I would have taken the 10D for my bird photography. Maybe a 10D comes into my body collection too soon.
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regards Rainer

please visit www.rsfotografia.com


Thank You
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