Pentax 50-135mm SDM DA* F2.8 w/ kenko x2 converter

**bezuidar** · 09-02-2010, 12:18 AM

Hi there

Just a question. I have added this lens to my K20D with a Kenko x2 converter.

The camera only pics up the focal length at 135mm and not 270mm as it should be with a x2 converter.

I have set the camera at Av priority, F8. Because the camera can only read focal length 135mm instead of 270mm, is my F-stop F8 or F16 now?

Fotos taken shows quite a lot of depth of field...

thanks

Bezuidar

Adam · 09-02-2010, 12:30 PM

You lose two effective stops with a 2x TC, so when your lens is at F8, the effective aperture is indeed F16. The DOF will be greater, but the effect isn't that dramatic due to the increased focal length.

**bezuidar** · 09-02-2010, 09:47 PM

Thanks for the info, make sense!

09-02-2010, 12:18 AM	#1
bezuidar Site Supporter Join Date: Aug 2010 Location: Centurion, South Africa Photos: Gallery Posts: 377	*Pentax 50-135mm SDM DA F2.8 w/ kenko x2 converter** Hi there Just a question. I have added this lens to my K20D with a Kenko x2 converter. The camera only pics up the focal length at 135mm and not 270mm as it should be with a x2 converter. I have set the camera at Av priority, F8. Because the camera can only read focal length 135mm instead of 270mm, is my F-stop F8 or F16 now? Fotos taken shows quite a lot of depth of field... thanks Bezuidar

09-02-2010, 12:30 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 49,612	You lose two effective stops with a 2x TC, so when your lens is at F8, the effective aperture is indeed F16. The DOF will be greater, but the effect isn't that dramatic due to the increased focal length. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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09-02-2010, 09:47 PM	#3
bezuidar Site Supporter Join Date: Aug 2010 Location: Centurion, South Africa Photos: Gallery Posts: 377 Original Poster	Thanks for the info, make sense!

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