Tele Connverter + DA* lens = AF?

Magnus W · 01-09-2008, 11:08 AM

Hello.
As the header says: Can you use autofocus on the DA* 50-135 with, for instance the Rear Converter-A 2X-S? Some says yes, others say no. And exactly what contacts are needed on the converter for the SMD to work?

question, questions -- MW

blende8 · 01-09-2008, 11:40 AM

Originally Posted by Magnus W

Hello.
As the header says: Can you use autofocus on the DA* 50-135 with, for instance the Rear Converter-A 2X-S? Some says yes, others say no. And exactly what contacts are needed on the converter for the SMD to work?

Currently there is no converter known that works with SDM.
There is an extension tube though, the Kenko Uniplus tube 25, that works.
So, in principle it is possible.
Why it's not working with the converters, nobody knows.

EDIT: What I wrote here is apparently wrong. See below.

*Tyama* · 01-09-2008, 12:12 PM

I tried my DA* 16-50 with a Rear Converter A 2X-S on a K10D and can verify no AF with this combination. Also if I remember right the camera asked for a focal length for SR on start up.

Don't have any answers on the contacts.

Magnus W · 01-09-2008, 12:39 PM

Bummer!
I thought it sounded too good to be true.

But thanks for quick answers.

-- MW

*dkittle* · 01-09-2008, 12:47 PM

I have used my Tamron 1.4x converter with the DA* 50-135mm and SDM continues working. I have noticed that the AF system hunts even more. Usually it hunts and doesn't lock, but if I ease up on the shutter release and again depress half way, it'll lock instantly. Kind of a wrr, wrrr, wrrr, flashing AF indicator, let go of shutter release, press shutter release half way and I get instance AF confirmation.

blende8 · 01-09-2008, 01:42 PM

Originally Posted by dkittle

I have used my Tamron 1.4x converter with the DA* 50-135mm and SDM continues working.

That's interesting!
Could you please post a photo of the converter, front and back?

This hunting is the same with my tube. Strange ...

TDN · 01-09-2008, 02:06 PM

Originally Posted by blende8

Currently there is no converter known that works with SDM.
There is an extension tube though, the Kenko Uniplus tube 25, that works.
So, in principle it is possible.
Why it's not working with the converters, nobody knows.

I think both Tamron and Kenko converters have the necessary contacts for Powerzoom and SDM...

http://images1.buzzillions.com/image...315718_300.jpg

blende8 · 01-09-2008, 03:02 PM

Originally Posted by TDN

I think both Tamron and Kenko converters have the necessary contacts for Powerzoom and SDM...

Yes, the Kenko has all the contacts but does not work. I have word on this from more than one.
My personal opinion is that it has to do with the depth of the powerzoom contacts.
For example, the triplet set of tubes from Kenko does not work, too.

01-10-2008, 08:46 AM

My Kenko 1.5 teleconverter works just fine with my DA* 50-135 lens. I use it all the time with no problems. Who ever said it doesn't work, might have a defective one.

Kenko | 1.5x DG AF Tele-Converter for Pentax AF | K15AFDGPK

Hapo · 01-10-2008, 09:17 AM

How do you like that Kenko 1.5x, generally speaking?

01-10-2008, 09:42 AM

Originally Posted by Hapo

How do you like that Kenko 1.5x, generally speaking?

I like it, though I have no experience with any other TC. I don't have any images with me that I can post but I can do it later when I get home.

Talisker · 01-10-2008, 10:23 AM

Originally Posted by TDN

I think both Tamron and Kenko converters have the necessary contacts for Powerzoom and SDM...

The Tamron and Kenko 1.4x converters are identical apart from the name (I've had a Tamron for a couple of years, my wife just bought a Kenko one!). Unsurprisingly, both of them work with my 50-135mm!