Nikkor 18mm f4 AI sharpness on corners?

Started Jun 20, 2013 | Discussions thread
HSway
Senior MemberPosts: 2,756
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Re: makes no sense
In reply to gammada, Jun 24, 2013

gammada wrote:

brightcolours wrote:

A 18mm prime on APS-C? Why? You are better off just using a 18-55mm VR kitlens, to be frank.

If you were talking about a D700 instead, it would make sense.

Just look at an UWA zoom for APS-C. Either the Tokina 12-24mm f4 DX, or the Sigma 10-20mm f4-5.6 DC. Or if you have a bit more money to spend, either the Tokina 11-16mm f2.8 DX or the Sigma 8-16mm DC.

Any idea on how sharp is the Tokina on the corners? Price is spot on for me.

As for why would I want an 18mm lens on an APS-C sensor, well, it all has to do with geometric distortion. Since the photos I sell must have perfectly aligned horizontal and vertical lines, I'm a bit afraid of going wider and then having to do extensive work fixing that distortion.

There isn’t a reliable relation between the FL and amount of the distortion. Some lenses have minimum distortions at very wide angles. For example the Sigma 8-16 has distortions close to zero at 14mm.

Nikkor 10-24 has negligible distortion at 14 and 18mm and close to non-existent in between.

Tokina 11-16 at 16mm and the 12-24 has also very little distortion at 18mm.

11-16 is the sharpest of the lot followed closely by Sigma – including the corners. They are all very good and the (lowish) price of the Tokina 12-24 should go down with the recent release of 12-28 - could be interesting on a second-hand market.

I expect the sharpest dx uwa lenses will become the new Samyang 16mm f/2.0 ED available in a few weeks in Europe (Samyang has it for 'ultra wide' but I see it more like bordering on wide angle) and the delayed Samyang 10/2.8 ED. Distortion data are not available yet I think, that is to be checked. Excessive distortions could be a problem for this shooting. For "perfectly aligned horizontal and vertical lines.." though, you will always need to do appropriate corrections, often run automatically in many software applications. 18 mil lens for architectural/interior photography is typically not wide enough. If you have no special reasons I’d recommend some of the dx UWA zooms where the zooming function is extremely useful, sharpness high and the price reasonable.

good luck,

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