new 1.4 teleconverter

tkon · 09-23-2014, 06:37 PM

after reading the PENTAX review on the new 1.4 teleconverter it was not recommended for use with 70-300 consumer zoom which I had recently purchased
why is that and what is suggested in lieu on using a Pentax converter?

**sergysergy** · 09-23-2014, 07:51 PM

All TCs work better with fast lenses because you lose some stops. The 70-300 is not fast enough. It may work in bright days though.

https://www.pentaxforums.com/articles/photo-articles/k-mount-teleconverter-guide.html

**jpzk** · 09-23-2014, 08:03 PM

Good question which leads me to another one:

Would this TC work with the DA 55-300 ?
I "almost" let my son use my converter (that same new HD 1.4x) on that lens of his but saw that the elements were moving while zooming .... wouldn't that cause the teleconverter and the lens components to "knock" against one another ?

MadMathMind · 09-23-2014, 08:21 PM

Originally posted by jpzk

Good question which leads me to another one:

Would this TC work with the DA 55-300 ?
I "almost" let my son use my converter (that same new HD 1.4x) on that lens of his but saw that the elements were moving while zooming .... wouldn't that cause the teleconverter and the lens components to "knock" against one another ?

There is a list:
http://c758710.r10.cf2.rackcdn.com/files/support/manual/1394730000_DA_Rear_c...lity_Chart.pdf

The 55-300 is explicitly listed as compatible, although autofocus may not work toward the long end unless you have a ton of light. Usually, minimum aperture f/8 is the absolute best you can hope for in phase detection autofocus systems, and 1.4 x 5.8 = 8.12 is right at the limit. At the short end, it should still be ok. At max focal length, you will do best to switch to live view. That should work.

**sergysergy** · 09-23-2014, 08:42 PM

My 55-300 works with the Tamron 1.4x. So does the 18-135 WR but you need good light. The rear elements do not protrude too much so I do not think there should be a problem.

mtux · 09-23-2014, 09:04 PM

Originally posted by jpzk

Would this TC work with the DA 55-300 ?

The AF won't work in the range of 135mm to 300mm because the lens become about f/5.6 thus with addition of the TC it will be an f/8 lens (One stop light loss) So only in very bright daylight the AF may work! or may not work at all! And the Viewfinder will be dim for manual focusing too.

Sandy Hancock · 09-23-2014, 09:07 PM

The HD DA 1.4x Rear Converter is designed to work optimally with lenses with a widest aperture of f/4.0 or faster.

It will work with the DA55-300, just not optimally. Certainly, no damage will be done.

Hemppo · 09-23-2014, 11:42 PM

I have da55-300 + tc1,4 combo in use. It works but it really isn't the best pair. At the long end the IQ and focus performance will drop significantly.

That's the reason why I'am currently waiting for a da*300 to be delivered...

bvanes · 09-24-2014, 10:15 AM

Did someone test the TC 1.4 converter with a SMC F* 4.5 300?

**boriscleto** · 09-24-2014, 10:19 AM

The 55-300 works fine with a Vivitar Series 1 1.4x.

09-23-2014, 06:37 PM	#1
tkon Inactive Account Join Date: Jan 2014 Posts: 1	new 1.4 teleconverter after reading the PENTAX review on the new 1.4 teleconverter it was not recommended for use with 70-300 consumer zoom which I had recently purchased why is that and what is suggested in lieu on using a Pentax converter?

09-23-2014, 11:42 PM	#8
Hemppo Senior Member Join Date: Oct 2008 Location: Hämeenkyrö, Finland Posts: 190	I have da55-300 + tc1,4 combo in use. It works but it really isn't the best pair. At the long end the IQ and focus performance will drop significantly. That's the reason why I'am currently waiting for a da300 to be delivered... Last edited by Hemppo; 09-24-2014 at 01:23 AM.*

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09-23-2014, 07:51 PM	#2
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,176	All TCs work better with fast lenses because you lose some stops. The 70-300 is not fast enough. It may work in bright days though. https://www.pentaxforums.com/articles/photo-articles/k-mount-teleconverter-guide.html

09-23-2014, 08:03 PM	#3
jpzk Site Supporter Join Date: Jan 2009 Location: Québec Photos: Gallery \| Albums Posts: 8,251	Good question which leads me to another one: Would this TC work with the DA 55-300 ? I "almost" let my son use my converter (that same new HD 1.4x) on that lens of his but saw that the elements were moving while zooming .... wouldn't that cause the teleconverter and the lens components to "knock" against one another ?

09-23-2014, 08:21 PM	#4
MadMathMind Veteran Member Join Date: Dec 2013 Location: Houston, TX Photos: Gallery Posts: 1,717	Originally posted by jpzk Good question which leads me to another one: Would this TC work with the DA 55-300 ? I "almost" let my son use my converter (that same new HD 1.4x) on that lens of his but saw that the elements were moving while zooming .... wouldn't that cause the teleconverter and the lens components to "knock" against one another ? There is a list: http://c758710.r10.cf2.rackcdn.com/files/support/manual/1394730000_DA_Rear_c...lity_Chart.pdf The 55-300 is explicitly listed as compatible, although autofocus may not work toward the long end unless you have a ton of light. Usually, minimum aperture f/8 is the absolute best you can hope for in phase detection autofocus systems, and 1.4 x 5.8 = 8.12 is right at the limit. At the short end, it should still be ok. At max focal length, you will do best to switch to live view. That should work.

09-23-2014, 08:42 PM	#5
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,176	My 55-300 works with the Tamron 1.4x. So does the 18-135 WR but you need good light. The rear elements do not protrude too much so I do not think there should be a problem.

09-23-2014, 09:04 PM	#6
mtux Veteran Member Join Date: Apr 2013 Location: the Netherlands Photos: Gallery \| Albums Posts: 2,444	Originally posted by jpzk Would this TC work with the DA 55-300 ? The AF won't work in the range of 135mm to 300mm because the lens become about f/5.6 thus with addition of the TC it will be an f/8 lens (One stop light loss) So only in very bright daylight the AF may work! or may not work at all! And the Viewfinder will be dim for manual focusing too.

09-23-2014, 09:07 PM	#7
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,276	The HD DA 1.4x Rear Converter is designed to work optimally with lenses with a widest aperture of f/4.0 or faster. It will work with the DA55-300, just not optimally. Certainly, no damage will be done.

09-24-2014, 10:15 AM	#9
bvanes Site Supporter Join Date: Sep 2010 Location: Haarlemmermeer Photos: Gallery Posts: 13	Did someone test the TC 1.4 converter with a SMC F* 4.5 300?

09-24-2014, 10:19 AM	#10
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,477	The 55-300 works fine with a Vivitar Series 1 1.4x.