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Egg Salad · 02-20-2010, 07:38 AM

I've got some questions regarding Tamron's focus clutch system - but this may also apply to Sigma's 20-28mm f/1.8 Macro primes.

If both camera and lens are set to AF I have no manual control over focusing - right?
When I set the camera to MF but leave the lens on AF the lens can't be focused at all.
And if I set the lens to MF and the camera to AF the focus ring will just rotate like any other screw driven lens.

Is this correct?

Zebooka · 02-20-2010, 09:17 AM

Originally posted by Egg Salad

I've got some questions regarding Tamron's focus clutch system - but this may also apply to Sigma's 20-28mm f/1.8 Macro primes.

If both camera and lens are set to AF I have no manual control over focusing - right?
When I set the camera to MF but leave the lens on AF the lens can't be focused at all.
And if I set the lens to MF and the camera to AF the focus ring will just rotate like any other screw driven lens.

Is this correct?

1. Yes, see next point
2. Yes, you would roll focus ring, but distance scale wont rotate (if lens set to AF).
3. Yes, your could burn your AF motor. Also focus ring will rotate when camera does AF.

Raybo · 02-20-2010, 09:33 AM

http://www.tamron.com/assets/pdfs/A001_70200.pdf

Egg Salad · 02-20-2010, 10:38 AM

Ok, thanks. Just wanted to have it confirmed.

02-20-2010, 07:38 AM	#1
Egg Salad Veteran Member Join Date: Jul 2009 Location: Berlin, Germany Posts: 344	Questions about dual clutch focusing system (Tamron 70-200): I've got some questions regarding Tamron's focus clutch system - but this may also apply to Sigma's 20-28mm f/1.8 Macro primes. If both camera and lens are set to AF I have no manual control over focusing - right? When I set the camera to MF but leave the lens on AF the lens can't be focused at all. And if I set the lens to MF and the camera to AF the focus ring will just rotate like any other screw driven lens. Is this correct?

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02-20-2010, 09:17 AM	#2
Zebooka Veteran Member Join Date: May 2008 Location: Russia, Siberia, Novosibirsk Posts: 323	Originally posted by Egg Salad I've got some questions regarding Tamron's focus clutch system - but this may also apply to Sigma's 20-28mm f/1.8 Macro primes. If both camera and lens are set to AF I have no manual control over focusing - right? When I set the camera to MF but leave the lens on AF the lens can't be focused at all. And if I set the lens to MF and the camera to AF the focus ring will just rotate like any other screw driven lens. Is this correct? 1. Yes, see next point 2. Yes, you would roll focus ring, but distance scale wont rotate (if lens set to AF). 3. Yes, your could burn your AF motor. Also focus ring will rotate when camera does AF.

02-20-2010, 09:33 AM	#3
Raybo Veteran Member Join Date: Dec 2007 Posts: 872	http://www.tamron.com/assets/pdfs/A001_70200.pdf

02-20-2010, 10:38 AM	#4
Egg Salad Veteran Member Join Date: Jul 2009 Location: Berlin, Germany Posts: 344 Original Poster	Ok, thanks. Just wanted to have it confirmed.

Questions about dual clutch focusing system (Tamron 70-200):

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