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Author Topic: Nikon lens confusion  (Read 1986 times)

PeterAit

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Nikon lens confusion
« on: December 29, 2008, 01:36:00 pm »

Hi all,

I have been using my Nikon D80 with the 18-135mm f3.5-5.6G ED kit lens and the Sigma 10-20 mm DC HSM wide angle zoom. I have liked the results, but some posts on this site suggest that I could get considerable better sharpness with better lenses. But, I am a bit confused. I see that Nikon SLRs have 2 sensor sizes: DX at 24x16mm (which the D80 has) and FX at 24x36mm (the D3, for example). How does this relate to lens choices? Nikon has a series of lenses specifically for DX sensor cameras and then others that do not specify they are for a particular sensor size. So, 3 questions:

1) Are the focal lengths of the DX series lenses the actual focal lengths or the "35mm equivalent" focal lengths?
2) Can I use non-DX Nikkor lenses on my D80?
3) If the answer to (2) is yes, will the effective focal length on the D80 be longer because of the smaller sensor?

Thanks in advance.

Peter
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Peter
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DarkPenguin

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Nikon lens confusion
« Reply #1 on: December 29, 2008, 01:55:31 pm »

Quote from: PeterAit
1) Are the focal lengths of the DX series lenses the actual focal lengths or the "35mm equivalent" focal lengths?

They are the actual focal lengths.
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Chairman Bill

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Nikon lens confusion
« Reply #2 on: December 29, 2008, 02:35:19 pm »

You can use non-DX lenses on your camera, but there is a 'conversion factor' of about x1.5 to apply to the effective focal length. Your 10-20 zoom has a field of view equivalent to that of a 15-30mm on a full-frame DSLR like the D3. A non-DX lens such as a 70-210 zoom, on your D80 would give you a focal length equivalent to that of a 105-315mm zoom on a full-frame camera, a 24mm would give you a field of view equivalent to a 36mm, and so on. Non-DX lenses give an advantage in telephoto terms because a 200mm becomes a 300mm, but any non-DX wideangles become less wide.

Tony Beach

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Nikon lens confusion
« Reply #3 on: December 29, 2008, 04:21:09 pm »

Quote from: PeterAit
1) Are the focal lengths of the DX series lenses the actual focal lengths or the "35mm equivalent" focal lengths?
They are the actual focal lengths.

Quote
2) Can I use non-DX Nikkor lenses on my D80?
Yes, and you can even use your DX lenses on an FX camera.

Quote
3) If the answer to (2) is yes, will the effective focal length on the D80 be longer because of the smaller sensor?
"Effective focal length" is a misnomer.  The main issue is that it ignores "effective" aperture as it relates to DOF.  For narrower DOF you will need a faster lens on DX than on FX, about one stop faster.  Can you imagine a 200mm f/8 lens?  That is the practical "equivalence" of the longest end of the lens you are using now, so it becomes glaringly obvious how much better a faster lens will be at the longer focal lengths you are using as far as creative potential (such as potential bokeh) is concerned.
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