I Dare You!

by peter_budo

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24
votes
4answers
4k views

Does my crop sensor camera actually turn my lenses into a longer focal length?

So, I mount a 200mm lens on my Canon 450D. It effectively becomes a 320mm lens. Is this the equivalent of 320mm on a full frame camera? That is, from what I've figured out I get an equivalent field of ...
25
votes
3answers
12k views

How can I calculate what the effect of an extension tube will be?

There must be a mathematical description of the difference that an extension tube makes to a lens -- is it something that can be easily described? (For example, with teleconverters you can say things ...
5
votes
2answers
489 views

How do zoom, magnification, and focal length relate?

Zoom lenses and cameras with superzooms are often sold with a times ("×") zoom number — like a 12x zoom or 30x zoom. The question How do I convert lens focal length (mm) to x-times optical zoom? ...
5
votes
2answers
1k views

How can I estimate the reproduction ratio of an unknown macro setup?

If I have a macro setup consisting of more than a normal 1:1 lens (tubes, reversal, or anything else), how can I measure the reproduction ratio (2:1, 1:1, 1:2, 3:1, etc.)? What process can I follow ...
4
votes
1answer
894 views

Does maximum aperture change with focus distance with the Canon 60mm f/2.8 macro lens?

This site says The Canon EF-S 60mm f/2.8 Macro USM Lens loses 1/2 stop at 1:5, 1 stop at 1:3, 1.5 stops at 1:1.5 and 2 stops at 1:1 (lifesize). Can anyone confirm that at 1:5 magnification, ...
6
votes
2answers
3k views

How can I calculate magnification ratio I get by reversing a lens?

I am looking for a way to mathematically determine the maximum magnification ratio that is possible/practical to achieve by reverse mounting a non-macro lens, prior to purchasing the lens. See ...
8
votes
3answers
1k views

How Much Can Lens Magnification Be Improved Without Significantly Lowering Image Quality?

Currently I own only a 1X magnification macro lens (35mm F/2.8) but I am playing with a rented Canon MP-E 65mm lens which can go to 5X. The photography at that magnification is a world apart! The ...
3
votes
1answer
146 views

What is Effective Aperture?

What is Effective Aperture? And how it can affect my exposure? Also how does it relate to magnification? A question that talks about effective aperture but without details