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Old May 25, 2011, 10:13 PM   #1
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Default Which is Sharper? FA 300mm f4.5 + AFA 1.7x or Sigma 150-500mm?

Hi All,

I'm in the process of deciding between the two setup. Because of poor lighting condition (under shade), I will have to shoot wide open very often.

My question is - When shooting wide at max zoom with the FA 300mm + AFA 1.7x and the Bigmos, which one is sharper?

Appreciate your help if you have experience with the two set up.
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Old May 26, 2011, 4:06 PM   #2
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Hi calvinlo,

I can't speak for the Sigma, since I've never owned one. From what I've read, it's a bit sharper than the Bigma wide open at 500, or at least that's been my impression from user accounts. My impression from what I've seen posted from this lens is that my FA*300/4.5 + 1.7x AFA combo is sharper, but I'm biased. . .

I've used the FA*300/4.5 + 1.7x AFA, and have never worried about shooting the combo wide open. I've shot this combo with every body I've owned, and this is the main reason why I've not obtained any of the Sigma xx>500 zooms. At just a @2.3 lbs (1070g) it's considerably more compact and lighter than any of the Sigma >500 zooms.

Realize that at f7.7 max aperture, it's slower than any of the Sigmas by about 1/3-2/3 stop, so you'd have to shoot it at a slightly higher ISO, and AF in marginal light might be slightly more difficult, but in most daylight situations, AF has been not much of a problem for me, mainly because of the focus limiting that the AFA imposes which cuts down on lock to lock hunts significantly.

I'm attaching 5 examples from 4 different bodies. All are wide open (showing f8 as the aperture since the AFA automatically multiplies by 1.7x and rounds to the nearest "normal" Av) except #2, which was shot at an indicated f10, so would be @ f5.9 at the lens. #1 is with the K100D, #2&3 are with the K10, #4 is with the K20, and #5 is with the K-7.

All were handheld and have been processed with sharpening and resizing, but I try to only sharpen to compensate for the softening caused by the downsizing.

This combo is pretty much my default carry around birding lens.

Scott
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Old May 26, 2011, 10:44 PM   #3
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Those are fantastic shots! I'm amazed that they are taken wide open. I hope the kenko 1.5x (which I also have) will work just as well.

Anyway, thank you very much for your pictures - they're certainly worth a thousand words. I've decided to go for the FA 300mm f4.5.
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Old May 31, 2011, 1:18 AM   #4
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My first shots with the FA 300mm f4.5 coupled with the Kenko 1.5x...

The Yellow-vented Bulbul was slightly more than 15m away...with bad lighting. The shots are highly cropped from 12mp to about 3mp.

Shot wide


Shot while stopping down 2/3 stop


Initial Impression - Not bad at all, sharp and no CA, no PF...I like it. The experience this time is so different compared to when I used the kenko with the DA 60-250mm last time. Now I understand that primes and teleconverters are really made for one another. Next time I will try the FA 300mm with the AFA 1.7x when lighting condition is better.
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Last edited by calvinlo; May 31, 2011 at 7:49 PM.
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Old Jun 4, 2011, 7:01 PM   #5
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The FA* is sharper.
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