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Old Mar 26, 2007, 9:22 AM   #1
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i want to buy a tele-zoom for my K100D.
i would like as much zoom as possible (animals & birds)
and i want to have fast focus !

important note, if AF or SR will not work in some cases, please point it, because i like to have them.

another important note, i looked at my pictures, and with the 50-200 i am using almost just the 200mm !!!
so this is the reason i want bigger zoom

currently i have 18-55 & 50-200 & TC tamron 1.4x

my thoughts were -

Sigma 100-300 F4,
this way i will have 100-300 with the best quality
with the TC 1.4 i will have a very good quality at 420mm F5.6 (i assume that TC will lower the quality),
people say that the SR will not work so good, because the camera doesn't know that i attached TC.

and now... lets talk about bigma (50-500 F4.0-6.3)
it's heavy ! i am afraid from it !
but 50-500mm... tempting

but if you will say that 100-300 is so much better, and with TC, it will still be better, then there is no issue.

please help...

thanks !

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Old Mar 26, 2007, 10:13 PM   #2
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Since you already own a TC and the DA 50-200, you might want to look around for one of the Pentax *300 lenses (there are several versions). I have the A*300 f4 (auto exposure, manual focus)and it's the best and sharpestlens I have - I love it. I don't find much of a need for something between 200 and 300 (I also have the DA 50-200), so the DA and the A*300 is a perfect combination for me, and the Pentax prime 300 lenses should be sharper than one of the zooms.

I know what you mean about the weight of the Bigma - it's too much for me!
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Old Mar 27, 2007, 1:37 AM   #3
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PERSONALLY, I find the Sigma 70-300mm and Tamron 1.4x TC a great and low cost solution to those desires.

And with the TC it is effectively a 630mm lens in 35mm terms.
Not quite the BIGMA's native 750mm, but a whole lot lighter, and a TON less money.

And I notice (other than the one stop of light loss) very little to no IQ impact of the Tam TC with. And except in very low (like well post sunset) light, very little AF impact either on the 10D dispite the effective f/8 at 300mm with the TC... not sure if the 100D's AF is as good.
I won't say it never hunts/misses in those conditions, but rare and always gets it on second try. Never a problem before sunset.

And as a bonus it is also, while not a 1:1, but still decent 1:2 macro lens.

(The Tamron 70-300mm seems much the same, but I haven't used one)

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