200-400 VR does not equal prime lens sharpness?

Started Nov 2, 2006 | Discussions thread
Thom Hogan Forum Pro • Posts: 13,660
Re: 200-400 VR does not equal prime lens sharpness?

Jonathan F/2 wrote:

I was looking at this review, and it made it seem like the 200-400
VR was equal to the sharpness of the 300.

Did you look at the samples? It seems clear to me that the 300mm f/2.8 stopped down to f/4 gets a sharpness benefit of the stopping down that the 200-400mm f/4 doesn't get. So at 300mm f/4, the 300mm lens is a bit better, as you'd expect.

To get to 400mm, you have to add the 1.4x to 300mm (okay, we're now comparing 420 v. 400). Both lenses are now being used wide open, and the effects of the converter are now hurting the 300mm. The 200-400mm is now a bit better, again as you'd expect.

I see two problems with the 200-400mm:

1. Because it's f/4, you're almost always using it wide open. It isn't quite as good at f/4 as it is at f/5.6.

2. It doesn't handle TCs very well. Even the 1.4x requires you to stop down a stop to get what I'd call good results, so we're now at f/8, yuck. The 1.7x and 2x are unusable on the 200-400mm with a D2x, IMHO (you get the double whammy: at 2x you really need to stop down at least two stops to get the best sharpness, which puts you past the visible diffraction point of the D2x; moreover, you're at f/16, which means you're likely to have boosted ISO to keep your shutter speeds up).

Honestly, I was somewhat disappointed image-wise with the 200-400.
While very good, I would not say this lens is at prime quality as
some people would say.

It's darned close (a better example to test against would be the 300mm f/4 AF-S, by the way), which is surprising for a big zoom. But it isn't as good as the f/2 or f/2.8 primes.

If anything, I find this a very expensive
complimentary lens as opposed to a neccessary purchase.

I would say it differently: it's a situational or compromise lens. There are a few situations where it excels due to the zoom flexibility. But if you're always using it at the long end as a replacement for a prime, you're making a slight compromise. The 400mm f/2.8 at f/4 is better than the 200-400mm, for example.

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Thom Hogan
author, Nikon Field Guide & Nikon Flash Guide
editor, Nikon DSLR Report
author, Complete Guides: D50, D70, D100, D200, D1 series, D2h, D2x, S2 Pro
http://www.bythom.com

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