| Joined: | Sun Apr 1st, 2012 |
| Location: | South Lakeland, UK |
| Posts: | 4066 |
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They seem to be going for around £200 on fleabay.
I assume that the DX lenses give their rated focal length on a DX body?
As JK says, the focal length of all lenses is as stated on the lenses.
Nikons DX lenses have a smaller image circle, (cheaper to produce). They can be used on FX bodies but the FX body will switch it's sensor to DX area by default, if you disable that you get extreme vignetting outside the DX image area. That's it. Some DX zooms do go some way to filling the FX sensor at the wide end I believe but I have never experimented.
Using an FX lens on a DX body has the advantage of better edge and corner sharpness because that's where all lenses tend to have some limitations and with an FX lens on a DX body you don't get to see the corners of the image circle, which in part causes the vignetting.
With the exception of the Sigma 10-20 which I no longer have and the 18-105 which I keep for IR, all my lenses are FX and have been since I got my D1 in 2006, I decided the DX was a temporary expedient until Nikon figured how to make full size sensors. So I bought my lenses with that in mind.
The DX format does have some advantages but also drawbacks, better for long lenses, as Eric points out but far worse for wides. To get a serious wide you have to go to silly short lenses, with the accompanying distortion and other issues. After the D3 I find using a DX camera like looking at the world though a keyhole, which I tolerate if I have to but it's not my preference. As they say, your experience may vary!
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Robert.