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04-02-2007, 09:52 AM   #16
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QuoteOriginally posted by Richard Day Quote
I posted a short review of some of my initial findings here:
Lens tests by Richard Day
Doh! (slapping forehead) I guess I should actually READ the entire post before making a request!

04-03-2007, 01:45 PM   #17
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How about a 200mm F2.8?

In theory, you should be able to buy a lens which reaches to 200mm at F2.8 for under $1000. Sigma has the 80-200, and Tamron has just announced a 70-200, both constant F2.8. I can't find a price for the Tamron yet but the Sigma lists for under $1000 at www.slrgear.com. Weight in the 1100-1200g range, about 2/3 of a Bigma.

Then, by attaching TCs as needed, you can do 300mm at F4 (1.5xTC) or 400mm@F5.6 (2xTC). Cost and weight for 200mm lens and TCs are less than a 300mm or 400mm AF lens new, and weight is less as well. At F5.6 or less, post-TC, autofocus shouldn't suffer.

Downsides:

1. Conventional wisdom is that a 1.5xTC eats one stop of light, so that a 200/2.8 with a 1.5xTC *should* equal a 300/F4. But the 300/F4 might be clearer & sharper in practice.

2. With a 200mm lens, you can't attach a 2xTC to get 600/F8, which may be important to how you use your current 300/F4.

3. 200mm F2.8 K-mount lenses are hard to find, because there is so much more demand than supply.

Despite these problems, when I first looked at fast long lenses, I tentatively concluded that the best long-term buy was a constant F2.8 lens reaching to 200mm. On paper, they are more affordable and more portable. With the right selection of TCs, you can have 300/F4 and 400/F5.6 on demand---and you get an excellent 200/F2.8 lens in the bargain.

Am I missing something?

--Brett
04-03-2007, 07:49 PM   #18
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QuoteOriginally posted by Brett Turner Quote
In theory, you should be able to buy a lens which reaches to 200mm at F2.8 for under $1000. Sigma has the 80-200, and Tamron has just announced a 70-200, both constant F2.8. I can't find a price for the Tamron yet but the Sigma lists for under $1000 at www.slrgear.com. Weight in the 1100-1200g range, about 2/3 of a Bigma.

Then, by attaching TCs as needed, you can do 300mm at F4 (1.5xTC) or 400mm@F5.6 (2xTC). Cost and weight for 200mm lens and TCs are less than a 300mm or 400mm AF lens new, and weight is less as well. At F5.6 or less, post-TC, autofocus shouldn't suffer.

Downsides:

1. Conventional wisdom is that a 1.5xTC eats one stop of light, so that a 200/2.8 with a 1.5xTC *should* equal a 300/F4. But the 300/F4 might be clearer & sharper in practice.

2. With a 200mm lens, you can't attach a 2xTC to get 600/F8, which may be important to how you use your current 300/F4.

3. 200mm F2.8 K-mount lenses are hard to find, because there is so much more demand than supply.

Despite these problems, when I first looked at fast long lenses, I tentatively concluded that the best long-term buy was a constant F2.8 lens reaching to 200mm. On paper, they are more affordable and more portable. With the right selection of TCs, you can have 300/F4 and 400/F5.6 on demand---and you get an excellent 200/F2.8 lens in the bargain.

Am I missing something?

--Brett
Well thought out, Brett. Thanks for the input. In general, I agree with you. However, I just saw a Sigma 70-200 f/2.8 (used) go for almost $1100 on ebay! I checked and a new one (if available) from Sigma4less is around $750. I know supply and demand, but that's really nuts.
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