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Old Jan 3, 2007, 4:47 PM   #1
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[suP]Am i correct in asuming that if i had a 70-300 and added the 2xTC then the focal length would jump up to 140-600mm [/suP]

[suP]and with the 1.4x TC on the same lens would jump to 98-420mm am i right or have i completely lost the plot...???[/suP]
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Old Jan 3, 2007, 5:04 PM   #2
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You have made the correct deduction.

However there is no free lunch, the 2x TC will subtract 2 stops (f/4 becomes f/8 ) and the 1.4x will subtract 1 stop (f/4 becomes f/5.6). This could be enough to cause autofocus to fail. Second point, TCs magnify the center of the image and can cause excessive distortion if the lens and TC are not of the finest pro quality.

Not all TCs will work with all lenses. In fact lens elements may touch at certain points causing expensive damage.

Bottom line, TCs were meant to be used with pro grade prime telephoto lenses, not consumer grade telephoto zooms. Even then the 2x TC does produce visible image quality degradation while the 1.4x may be less visible.



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Old Jan 3, 2007, 5:12 PM   #3
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Thanks Bob,

Just wondered if getting a 1.4 would be cheaper then getting a Canon 100-400

or the Sigma 170-500 or 50-500 and getting a slightly cheaper zoom lens....But your right i'm going to save and get myself the longer lens...I was thinking about the 50-500 or 170-500 which one would you recommend out of the 2...??

Or would you suggest a different lens altogether...I want distance but for about £600.00 $1150.00 USD's
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Old Jan 3, 2007, 5:22 PM   #4
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Andrew, what do you want the lens for as this will make a difference on the choice.

One that I would suggest you add into the equation is the Tamron 200-500 which for about £650 will give some pretty tidy results! Again until the use is deduced thenmaking a recommendationwill be hard!!!
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Old Jan 3, 2007, 5:40 PM   #5
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I'd like to go out into the Great British Countryside and look for whatever wildlife/Birds there are...I live in Knowle West in Bristol and the only bloody Wildlife around here are Rats and Pidgeons...And i would shoot them but not with my Camera...Lol
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Old Jan 3, 2007, 5:45 PM   #6
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That's cool, have a look at the review on http://www.photozone.de/8Reviews/index.htmlwhich cover the lenses you have mentioned. For me it would be the 50-500 Sigma or 200-500 Tamron in the price range you are working to (Tamron being choice). You have Bristol Cameras near you so worth popping in as they seem to do both lenses you are talking about. Have a play, see what they feel like, get more opinions (especially those using them) and go from there.
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Old Jan 3, 2007, 5:52 PM   #7
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Do you mean the Tamron SP AF 200-500 f5-6,3 DI
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Old Jan 3, 2007, 5:52 PM   #8
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Yep
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Old Jan 3, 2007, 6:13 PM   #9
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Bristol Camera Company got it for £619.00 all in

I'm going to check Jessops as they say they can match plus 4%

Just looked and they got £30.00 off there lenses over £600.00

"BUT"!! They don't stock it or have it listed...Damn....

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Old Jan 3, 2007, 6:14 PM   #10
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I saw!!!! Nice
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