> I wonder if it makes a difference choosing between D or G version of any of the 1.4 or 1.8 50mm lens when using the lens reversed and coupled with a telephoto lens for macro photography.
As I think you know, the G lenses are hard to control aperture-wise, so when they're reversed you'd need to make special arrangements to keep its aperture open. Although not exactly rocket science, this is just something else to worry about with a G that you don't have to hassle with using a D lens - so I'd go with the D for that reason alone.
> I read at kenrockwell.com that the 50mm f1.4G was faster in AF but had worst distortion than 1.4D.
Are you sure you read that properly? The 50/f1.4 AFS G is the slowest AF of all of the 50mm's. None of them are quick, but the 1.4 AFS is the least quick.
As far as distortion goes, it's not a big deal. It's far less bad than many other lenses, and these days with software being what it is, virtually ALL lenses have a fair amount of optical distortion, field curvature and corner fall-off. I'm pretty sure that the designers are allowing those to creep in so that they can get other things - that cannot be accommodated in software. Even top-flight lenses such as the Nikon 24-70/f2.8 AFS and 70-200/f2.8 AFS have pretty noticeable optical distortion, to say nothing of the wider range models such as the 28-300 and 18-200. Even the prime 60/f2.8 AFS Micro has a surprising amount of field curvature and a little distortion.
Finally, the 50/f1.4 D and 50/f1.8 D have pretty minimal distortion, so even if that site is correct in saying that the 50/f1.4 G has worse distortion, that doesn't tell you very much. More distortion than "not very much" is not a very useful statement...
> For my intented use of the 50mm makes sense to spend more in the 1.4 version instead of 1.8?
I sure can't see it. For macro work you will be opening the reversed lens up, and while I'm not intimately familiar with the 50/f1.4 D, I do know that it isn't sharper than the 1.8 when both are wide open. But then again, that's with the light going in the usual direction; I sure don't know anything at all about how either of them work reversed. (I can't find the optical diagram at the moment, but I am pretty certain it's not one of the symmetric formulas.)
_____ Brian... a bicoastal Nikonian and Team Member
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