price and size not criteria is the 24-70 way better than the 24-85mm for landscapes

Started Jan 19, 2013 | Discussions thread
VincentR Regular Member • Posts: 124
Re: Yes. NT...

There's no doubt that the 24-70/2.8 will be sharper than the 24-85 VR, both in the centre and at the borders at the same f/stops, provided the shooting conditions allow the best technique to be used with each lens. This factor is often ignored.

When testing a lens for maximum optical performance, one should use a tripod and a stationary target. In these circumstances, the 24-70/2.8 will (or should) produce noticeably sharper results at the same f/stops..

However, following is a couple of examples of the sorts of comparisons which might be made in practice, in the field, without a tripod.

(1) The 24-70 at 70mm, F5.6, ISO 400 and at a shutter speed of 1/200th, compared with the 24-85 at 85mm, F5.6, ISO 100 and a shutter speed of 1/50th, based upon a very conservative 2-stop advantage of the VR system.

Let's suppose that neither focal length was quite long enough and that both images have to be cropped to some degree for a pleasing composition.

The 24-70 shot, although potentially sharper, has to be cropped more, which will reduce and perhaps even eliminate its advantage regards detail and sharpness.

In addition, the inevitable reduction in SNR and Tonal Range etc at ISO 400, which was necessary to achieve the higher shutter speed required, because the lens lacks VR, will reduce the resolution even more.

In such a situation, I suspect the cheaper and lighter 24-85 VR would produce better results.

(2) Let's compare both lenses at, say, 40mm in lighting conditions which are not ideal. Let's assume the 24-85 lens with VR has a 3 stop advantage, as claimed. We use the 24-70 at 1/160th, F2.8 and ISO 400. In the same lighting conditions, we can use the 24-85 VR at 1/20th (3 stops down), F4 and ISO 100.

Now, at F2.8 and 40mm, the 24-70 is probably not sharper than the 24-85 at 40mm and F4. The results at Photozone suggest this, testing both lenses with the Nikon D3X.

Again, the extra noise at ISO 400 will detract from the image sharpness of the 24-70, and the shallower DoF at F2.8 may not be desired. Again, the 24-85 produces at better result.

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