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03-26-2010, 03:36 PM   #16
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Here's som pictures at close focus

1st : Takumar old lens at 200mm

2nd : Tamron 18-250 @ 200mm

3rd : Tamron 18-250 @ 250mm

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Last edited by audiophil; 03-26-2010 at 03:42 PM.
03-26-2010, 03:39 PM   #17
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Another exemple at close focus

1st : Takumar old lens at 200mm

2nd : Tamron 18-250 @ 200mm

3rd: Tamron 18-250 @ 250mm
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Last edited by audiophil; 03-26-2010 at 03:45 PM.
03-26-2010, 03:55 PM   #18
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Now Infinite focus :

1 TAKUMAR 70-200 @200

2 TAMRON 18-250 @200

3 TAMRON 18-250@250

4 TAKUMAR 70-200 @200

5 TAMRON 18-250 @250
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03-26-2010, 03:59 PM   #19
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QuoteOriginally posted by Marc Sabatella Quote
Can you post samples shot at infinity focus? The phenomenon you describe is very well known at close distances, but shouldn't be an issue at infinity. But I've never used the 18-250 and can't say how it compares in practice. Some small discrepancy is to be correct - like maybe the actual focal length is 243mm instead of 250mm - but no way should it be coming out less than 200 at infinity.
Marc, it looks like you were right, close focus gives magnified result with the old Takumar lens, however at infinite focus pictures shows same angle of view with both lenses...

Why is that?

Thanks

Phil

03-26-2010, 09:41 PM   #20
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QuoteOriginally posted by audiophil Quote
Marc, it looks like you were right, close focus gives magnified result with the old Takumar lens, however at infinite focus pictures shows same angle of view with both lenses...

Why is that?

Thanks

Phil
It is the way the lenses were engineered. Internal focus and internal zoom result in the advantages of lenses that do not expand as they are focused and zoomed, and where the front element does not turn while you focus, but often only obtain their full rated mm at infinity focus.
03-27-2010, 06:30 AM   #21
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Ok thanks, makes perfect sense.

All the best,

Phil
03-27-2010, 06:51 AM   #22
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QuoteOriginally posted by Canada_Rockies Quote
It is the way the lenses were engineered. Internal focus and internal zoom result in the advantages of lenses that do not expand as they are focused and zoomed, and where the front element does not turn while you focus, but often only obtain their full rated mm at infinity focus.

I guess I'm invisible. That's exactly what I said earlier, but nobody seemed to notice. But you just show up and pointed to the obvious, and everybody notices. I guess God gave you more persuasion power than me.
03-27-2010, 09:57 AM   #23
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QuoteOriginally posted by flyer Quote
I guess I'm invisible. That's exactly what I said earlier, but nobody seemed to notice. But you just show up and pointed to the obvious, and everybody notices. I guess God gave you more persuasion power than me.
Yves, c'est la vie, malheureusement.

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