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Old Nov 7, 2003, 4:14 AM   #1
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Default Teleconverter and Hockey Pix

Hi All,
I am purchasing the 70-200mm VR lens (f2.8) for taking indoor hockey photos (using natural lighting) for my D100.

I understand that using a Teleconverter, that I lose 2 fstops. Will I lose the light gathering power that I need if I use a teleconverter with this lens at a hockey rink? [I understand that F2.8 is the min for shooting quality indoor hockey photos]

Do I still lose 2 fstops if I am using a VR lens ?
---I thought I read someplace that the VR lens enables you more flexibility.....

Which Teleconverter am I better off with the 1.4 or the 2x?

My objective with using the Teleconverter would be to get a 300MM lens, while still retaining a small fstop.....

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Old Nov 7, 2003, 8:45 AM   #2
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If you place the TC between the lens and the camera, the loss of light is a matter physics, so you will loose it no matter what lens you have. Nothing you can do about it. It's just a question of how much light you loose.

The more the magnifying power of the TC, the more light you loose. The 1.4x TC loose 1 fstop. The 2x TC looses 2 fstops. (This is why the odd "1.4"xTC value. Why not 1.5x? Makes the math easier.... It's because then you would loose slightly more than 1 fstop. Loosing exactly 1 fstop is more important than easy math.)

Personally, I wouldn't use a 2xTC. That will probably cost you too much light for indoor shooting.

You should still have VR, though.

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Old Nov 8, 2003, 8:16 PM   #3
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Eric S. brings up some good points, albeit waaaaay outta my league! :lol: . I do know that when I use my 2x TC, the autofocus is extremely slow. I can't imagine using it to shoot fast paced action such as hockey. But then again, I'm an amatuer.
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Old Nov 9, 2003, 8:50 AM   #4
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Almost all cameras (but I don't believe all, I'm not sure) do AF based on contrast detection. They sample the scene at the AF point and detect when it gets sharper, then they shift the focus in the direction that makes it more "in focus". Until it hits it's definition of "in focus".

The key is that "in focus" is detected by the constrast at the AF point. To detect constrast you need light. Without light making shadows and showing details, it's harder to detect constrast. If you add a teleconverter, you loose light, which makes detecting contrast harder (and therefor AF harder.)

This is one of the little thought of bonuses of the faster lenses (lenses with a smaller f-stop/larger apeture.) They provide more light to the AF system, and so could help the AF system work better.

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Old Nov 10, 2003, 12:21 AM   #5
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With the TC-14 II, your 70-200 f/2.8 would effectively become a 98-280 f/4. But since you already have the FOV crop of 1.5 from the smaller D100 sensor, then the combo would be equivalent to 147-420 f/4, and that without losing any of the benefits from the silent wave motor of that lens. Eric S is right about the light gathering abilities of a lens diminishing with teleconverters. with the TC-20 II, your lens would become a 210-600 f/5.6, but I've read by then the image degradation becomes more noticeable than in the TC-14 II.

As for VR, I suppose the marketing people would have you believe it's a miracle feature in lenses. It helps get that steadiness in certain shots, but if the subject moves then your desired image will be blurred regardless of VR. It will provide the 3 stops power to help get a reasonably sharp subjects (I've managed 1/5s once), VR has no barings on aperture size or the ammout of light that gets to the camera.
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