Re: Nikon D40 with 300mm lens AND teleconverter (Nikkor AF-S Teleconverter TC-20E II)

David J Taylor wrote:
greg@xxxxxxxxxxx wrote:

I see there's more to focal length measurements than I realised!

Yes, a simple rule is that with cameras like the D40, multiply the optical
focal length (the one on the barrel, and the speicifcation) by 1.5 to get
the equivalent filed of view, so the 18-55mm kit lens has the same FoV
as a 27 - 82mm lens on a film SLR, and the 70 - 300mm lens has a 105 -
450mm FoV.

That's misleading. Let's stick with focal length, and not confuse Greg with
FoV.

Greg says he's new to photography, so 70-300 and 105-450 are equally
meaningless, so I don't see that you've done him any favours anyhow. :-)

Greg, on a 35mm camera a 50mm lens gives a perspective similar to the human
eye, so a 300mm lense will give you a view like a 6x telescope. For a D40,
you will get a "normal" perspective through a lens around 50/1.5 = 33mm
focal length.

I think when you say, "a high zoom is essential", you mean a high
magnification is essential. ("Zoom" refers to a lense's ability to change
focal length.) A 300mm lens on a D40 will give you about 300/33 = 9x
magnification, like what you see through 8 or 10x binocs.

300*1.7 = 510mm, which mean 510/33 = 15x magnification. Or the other way
around, 300*1.5*1.7/50 = 15x.


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