teleconvertors

john ross · 01-15-2010, 10:02 PM

Hi,

I have a Sigma DC 75-300 f4/5.6 AF lens and I would like to know if there is a 1.4 or better teleconvertor that I can use with it and my K20D body and still retain auto focus.

Ole · 01-15-2010, 10:11 PM

Tamron-F AF Teleconverter - 1.4X Pz-AF MC4

It is a very decent 1.4x converter, supports screw-drive autofocus.

**Rense** · 01-16-2010, 03:59 AM

Hi John, welcome to these forums!
Probably you should have asked your question in the right section?

**Ash** · 01-16-2010, 01:39 PM

Welcome to the forum John - do be weary of where you post as it matters for archiving purposes.

The Tamron 1.4x TC is probably your best option, but will make AF function painstakingly slow and difficult in anything other then optimal lighting conditions, not to mention causing further image quality degradation to that of your existing consumer lens.

J.Scott · 01-16-2010, 01:48 PM

Originally posted by Rense

Hi John, welcome to these forums!
Probably you should have asked your question in the right section?

moved to lens discussion forum...

Oggy · 01-16-2010, 02:21 PM

Originally posted by Ole

Tamron-F AF Teleconverter - 1.4X Pz-AF MC4

It is a very decent 1.4x converter, supports screw-drive autofocus.

I to have the Tammy and it "supports" both screwdriver and SDM/HSM focus. When I say "supports" I mean that it might focus one in four times on a reasonably bright stationery subject. Then there is the loss of IQ.

TCs are not great.

**Lowell Goudge** · 01-16-2010, 02:52 PM

note that while a 1.4x TC will probably AF at the short end, it probably won't at the long end

at 300mm when you add the 1.4x you will have 450mm F8. Most AF only works to F6.7.

01-15-2010, 10:02 PM	#1
john ross New Member Join Date: Jan 2010 Location: Dubai Posts: 1	teleconvertors Hi, I have a Sigma DC 75-300 f4/5.6 AF lens and I would like to know if there is a 1.4 or better teleconvertor that I can use with it and my K20D body and still retain auto focus.

01-16-2010, 02:52 PM	#7
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	do you need AF supported note that while a 1.4x TC will probably AF at the short end, it probably won't at the long end at 300mm when you add the 1.4x you will have 450mm F8. Most AF only works to F6.7.

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01-15-2010, 10:11 PM	#2
Ole Administrator Join Date: Sep 2006 Location: Copenhagen, Denmark Photos: Gallery \| Albums Posts: 4,408	Tamron-F AF Teleconverter - 1.4X Pz-AF MC4 It is a very decent 1.4x converter, supports screw-drive autofocus.

01-16-2010, 03:59 AM	#3
Rense Site Supporter Join Date: Dec 2008 Location: Zetten - The Netherlands Photos: Gallery \| Albums Posts: 9,050	Hi John, welcome to these forums! Probably you should have asked your question in the right section?

01-16-2010, 01:39 PM	#4
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	Welcome to the forum John - do be weary of where you post as it matters for archiving purposes. The Tamron 1.4x TC is probably your best option, but will make AF function painstakingly slow and difficult in anything other then optimal lighting conditions, not to mention causing further image quality degradation to that of your existing consumer lens.

01-16-2010, 01:48 PM	#5
J.Scott Inactive Account Join Date: Mar 2007 Photos: Gallery Posts: 3,675	Originally posted by Rense Hi John, welcome to these forums! Probably you should have asked your question in the right section? moved to lens discussion forum...

01-16-2010, 02:21 PM	#6
Oggy Inactive Account Join Date: Sep 2009 Location: West Sussex UK Posts: 235	Originally posted by Ole Tamron-F AF Teleconverter - 1.4X Pz-AF MC4 It is a very decent 1.4x converter, supports screw-drive autofocus. I to have the Tammy and it "supports" both screwdriver and SDM/HSM focus. When I say "supports" I mean that it might focus one in four times on a reasonably bright stationery subject. Then there is the loss of IQ. TCs are not great.