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**Docbot** · 09-08-2014, 05:38 PM

I have updated the firmware and the 1.4x rear converter works great will my all primes and the 50-135mm zoom, but when I use it with my 18-135, the auto focus hunts and hunts. Sometimes it won't even focus.

Has anyone else experienced this? Any suggestions?

**pearsaab** · 09-08-2014, 05:49 PM

It works best with apertures of 4 or less. I don't think that lens has the speed to use the teleconverter.

Sandy Hancock · 09-08-2014, 05:50 PM

The converter is designed to work optimally with lenses having a maximum aperture of f/4.0 or faster. I assume you are using the 18-135 at the long end, so that might be your problem.

[edit]Beaten to it! What Amy said

[/edit]

**clackers** · 09-08-2014, 09:05 PM

Docbot, unfortunately you don't get something for nothing. You're getting 1.4 times the magnification, but losing the light ... the lens is being turned into an f4.9 to f7.8 one - wide open! No guarantees for the AF once you do that.

**sergysergy** · 09-08-2014, 10:16 PM

It will work in very good light conditions. Other than that you will have to use manual focus or live with the constant hunting. That is my case with the same lens and the Tamron 1.4

09-08-2014, 05:38 PM	#1
Docbot Site Supporter Join Date: Oct 2010 Photos: Albums Posts: 35	1.4x converter with 18-135 WR--autofocus hunts! I have updated the firmware and the 1.4x rear converter works great will my all primes and the 50-135mm zoom, but when I use it with my 18-135, the auto focus hunts and hunts. Sometimes it won't even focus. Has anyone else experienced this? Any suggestions?

09-08-2014, 05:50 PM	#3
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,275	The converter is designed to work optimally with lenses having a maximum aperture of f/4.0 or faster. I assume you are using the 18-135 at the long end, so that might be your problem. [edit]Beaten to it! What Amy said [/edit] Last edited by Sandy Hancock; 09-08-2014 at 05:51 PM. Reason: Too slow

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09-08-2014, 05:49 PM	#2
pearsaab Otis Memorial Pentaxian Loyal Site Supporter Join Date: May 2011 Location: Richmond, Virginia USA Photos: Gallery \| Albums Posts: 2,900	It works best with apertures of 4 or less. I don't think that lens has the speed to use the teleconverter.

09-08-2014, 09:05 PM	#4
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Docbot, unfortunately you don't get something for nothing. You're getting 1.4 times the magnification, but losing the light ... the lens is being turned into an f4.9 to f7.8 one - wide open! No guarantees for the AF once you do that.

09-08-2014, 10:16 PM	#5
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,175	It will work in very good light conditions. Other than that you will have to use manual focus or live with the constant hunting. That is my case with the same lens and the Tamron 1.4

1.4x converter with 18-135 WR--autofocus hunts!

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