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PostPosted: Sun Jul 05, 2009 1:37 am 
Hi,
I'm trawling this excellent web site and many others with the view of buying one of the Sigma 500mm offerings for wildlife. But after reading all the info and opinions, I'm beginning to wonder what use a long zoom is.

It would replace a 300mm f4 Nikkor and TC14 converter (420mm f5.6). Wide open (the only aperture that matters with wildlife), this combo has a relative resolution (MTU50) of 1847 in the centre and 1576 in the periphery. This translates to pin-sharp and sharp, soft appearance coming in at around 1400.

The Nikkor 80-400 f5.6 at 400mm wide open has 1781 in the centre and a woeful 1242 in the periphery (that surprised me). And the Sigma zooms are being compared to that benchmark. The prime lens with converter is sharper in the centre, and the zoom is picture-spoiling soft in the periphery. Do the Sigma 500's perform better at 400mm than the Zoom-Nikkor? Peripheral softness wide open seems to be an issue with the Sigmas, also.

The argument that the periphery doesn't matter with a tele because the subject is only in the centre seems for children! I would've thought that anyone caring about wildlife compositions would need a sharp periphery, and it's essential for landscapes.

The obvious advantage of the zoom is that you can back off quickly should the subject change or for a looser composition. By backing off a little with a zoom, you would have a slightly sharper 300mm lens of around f5, I suppose. With a few more seconds, I can remove the 1.4x converter and have a crackingly sharp and even 300mm f4 lens, that one review calls the closest to a perfect lens yet reviewed.

By adapting the 300mm prime to my Olympus 4/3 2nd body, I get a pin-sharp manual focus 600mm f4 image stabilised lens that weighs 1400 grams (and focusses closer than any of the zooms). My 300mm f4 and 1.4x, both ruggedly made, were purchased 2nd hand for less than the cost that the Sigmas are selling for 2nd hand.

I'm still interested in a long tele zoom; I guess I'm wanting to be convinced of their advantages:
Is the backing-off ability really valuable while working wildlife?
Does peripheral softness spoil your pictures, other than bullseyed shots?
And is anyone using a 1.4x converter with one and getting publication quality?
Many thanks!
Wayne Lawler :o


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PostPosted: Sun Jul 05, 2009 6:16 am 
I'm not surprised that the 300mm Nikkor gives you better performance than the 80-400mm zoom. If you're after absolute image quality, a prime is always going to be better than a zoom (all else being equal). Zooms compromise image quality for convenience, as you've so clearly explained in your post.

Are you able to live with the reduced quality for the convenience of backing away? Or is the image quality unacceptable and you require a prime? In this situation, I think the best thing for you to do is to rent the 80-400mm for a few days and then test it out in the field. Not many of the members on these boards do the sort of photography you're into at the level you're at. Thus we're not able to contribute in any meaningful way other than speculate or point you to MTF charts on the web ;)


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PostPosted: Sun Jul 05, 2009 9:22 am 
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Joined: Sun May 25, 2008 12:48 pm
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Location: UK
Have you ever had your subject get closer than expected so that you couldn't get it all in shot? If so, a zoom can be useful, but alternatively you could also use a 2nd body with shorter lens.

Can't comment on border softness as I use the Canon 100-400 which is quite consistent. Of course any softness such as misfocus can spoil a shot. When I use it with a TC, I find it incredibly difficult to get accurate MF so I rarely do so.

Not a practical option given you're on Nikon, but the sharpest telephoto zoom at the moment seems to be the Sony 70-400. Based on reviews at photozone, the Tamron 200-500 (up to 400) and Sigma 80-400 might be adequate too.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
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PostPosted: Mon Jul 06, 2009 12:54 am 
Pgtips and Popo,

That's a wealth of info and good advice. Thank you! I'll investigate those leads and ideas. Focus issues are a reason why I'm looking around to modernise. As my eyeballs become less and less nubile, I'm finding more and more missed focus disappointments when I review images on screen that I was confident about in camera.

Yes, a second body is another way to back-off, but it also takes a few seconds. It means a third body for me, because the second generally has a bigger blunderbus lens. There's a limit to what you can carry and fuss with.

Your question is searching - whether that situation arises often enough to go the zoom route. I've been covering fauna surveys recently, and find the young team members, all keen and well-equipped budding wildlife photographers, often get the shot with their auto-everything zoomers, while I fidget with my more clumsy pro gear. When I get the shot, it's sharper and closer, but often I just feel foolish! :?

I hear them saying to themselves, "This old guy is set in his ways, using gear from last century." But in fact I'm always looking for the better way...

Yes, Nikon 400mm users do get lens-envy looking across at Canon these days, unless they're wealthy weightlifters. I get choppered in to many locations, and the pilots take a dim view of me turning up with a giant lens. A tripod is bad enough! Vale the sharp and petite 400mm f5.6 Nikkor.

Thanks so much for your advice. It's a real help.
Wayne


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