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09-03-2009, 02:06 PM   #1
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Tamron 1.4 tc advice

I tried to photograph birds yesterday with my 100-300 zoom and felt like I couldn't get close enough. I am trying a Tamron 1.4 tc on my k20d. I have it inline with a 100-300 zoom and am focusing manually. I understand that my fstop will increase as it will need more light. Does the fstop on the k20d display accurately reflect the real fstop? Within its limitations, will I get reasonable pictures or should I return it and save for a longer lens? Any advice on using a teleconverter would be great.

Thanks,
Peter

09-03-2009, 02:20 PM   #2
Ash
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The K20D will tell you that the lens is f/4 when it's really f/5.6 (wide open when using the TC).
As a result, you may need to bump up EC by a stop or so to get adequate exposure.
09-03-2009, 03:29 PM   #3
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QuoteOriginally posted by Ash Quote
The K20D will tell you that the lens is f/4 when it's really f/5.6 (wide open when using the TC).
As a result, you may need to bump up EC by a stop or so to get adequate exposure.
Huh?

It's correct that the camera reports f/4 while it is actually f/5.6 with the TC.

But the camera should change other settings (shutter speed or ISO, depending on what mode the camera is in) to compensate for the light "lost" by the TC. You should not need to set EC.

I've read that someone had to set EC due to the peculiar behavior of the K10D's and K20D's (and maybe others') focusing screen. I can't confirm this with my 2 K10D bodies (they both have LL-60 screen), but even if you have to do this, it's a different problem.
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