b_yen2

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<p >I have the following in my hands now Tamron 400mm/4.0 Nikkor 400mm/3.5 Nikkor 500mm/4.0</p>

<p >I bought them all to try out... I plan on using them on a Canon 5D</p>

<p >-- Greg Peters</p>

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What was the result of your tests?<br>

I didn't realize the 400mm/3.5 was such a great lens. And, it beat out a Tamron 400mm/4 in tests.<br>

I have a Tamron 400mm/4, using it with a Nikon TC301 wide open..for a 800mm/f8 combo. I'm thinking of selling it, & getting a Nikon 400mm/2.8 (used with TC301 2x) or Nikon 400mm/3.5 (used with TC301 2x).<br>

There are some 400mm/2.8 available used for ~$1400 (heavily used)..suppose I stopped it down to f3.5, would it be as good as 400mm/3.5? Thinking of springing for a 400mm/2.8, instead of a used 400mm/3.5 ($1000 - $1600 used).</p>

<p>My application requires 800mm focal length, so the above solution is 400mm + 2x doubler. Another approach, is a 600mm/4 + 1.4x (840mm FL). However, the 600mm/4 is big & heavy, as is the 400mm/2.8 (15 lbs?). If the 400mm/3.5 is such a superior performer optically, then it also has the benefit of being lighter.</p>

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<p>I am considering 2 options:<br>

1) Nikon 400mm/2.8 EDIF + TC301 (2X) = 800mm/5.6<br>

2) Nikon 800mm/5.6 EDIF</p>

<p>I've tested a Nikon 400mm/2.8 EDIF in astronomy, on a star-field. Very well corrected, pinpoint stars even at the edges (well, they were symmetrically triangular shaped, not round). A TC300 (or 301) should give a nice image, maybe with some aberrations.<br>

How would a 800mm/5.6 compare with the above?<br>

Option 1) is more compact, as I need a 800mm lens for travelling around the world. The 800mm would be pretty bulky.</p>

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