Another Tele-converter question...


Classvino

Link Posted 02/04/2007 - 20:18
I want to move up a size in my lenses - been looking at the "Bigma" and similar sized zooms... I have assorted other lenses (mostly PK-A lenses) and thought that I might also pick up a tele-converter...

There's been a bit of talk recently here on these, and I've heard some info in other spots as well...

I realize that not all lenses work with all converters - at least that's what the things I've heard and read seem to indicate... Sigma, Tamron, Vivitar and others all make them, but they all say diffferent things about them...

I don't mind not having AF - I only use it a little bit anyhow, but I'd like to be able to use the metering on my K10D... Are there any recommendations as to which converter will work with the greatest number of lenses?

I was looking at the shorter teleconverter (1.4X), but recommendations on the 2X are equally welcome...

Thanks;
Jamie
--------------
MZ-6,K10D,K20D,Grip,DA*Zooms,DA 18-55-200 Kit,FA50,1.7TC,AFZ360
For Saleentax FA28-90,FA100-300,Sigma EX28-80,DC18-200,
Makinon 500mm Mirror

George Lazarette

Link Posted 02/04/2007 - 21:27
Perhaps the best all-round teleconverter for the K-mount is the Pentax F 1.7X AF. It provides auto-focus for any lens mounted on it - even manual focus lenses - and the quality, like all Pentax tele-converters, is very high.

The auto-focus mechanism has a limited range, so the main lens has to be close to correct focus (but not that close).

And of course, it has the Ka contacts, so the K10D will meter properly with it.

G
Keywords: Charming, polite, and generally agreeable.

McBrian

Link Posted 02/04/2007 - 21:51
Do not buy the Sigma EX APO 2x for use with Pentax lenses as most of these don't fit, the rear lens element collides with the front element of the converter, don't know if the 1.4x does the same but I hazard to say it does. Tamron make a nice AF 1.4x with the electrical contacts as do Kenko and I'm pretty sure they fit most Pentax lenses.

As George mentions I have found the Pentax 1.7x to be very good but they are commanding a rather high price (150+) on ebay at the moment.
Cheers
Brian.
LBA is good for you, a Lens a day helps you work, rest and play.

fatspider

Link Posted 03/04/2007 - 18:22
McBrian wrote:
Do not buy the Sigma EX APO 2x for use with Pentax lenses as most of these don't fit, the rear lens element collides with the front element of the converter, don't know if the 1.4x does the same but I hazard to say it does. Tamron make a nice AF 1.4x with the electrical contacts as do Kenko and I'm pretty sure they fit most Pentax lenses.

As George mentions I have found the Pentax 1.7x to be very good but they are commanding a rather high price (150+) on ebay at the moment.

The Bigma has a two position lock on the barrel, one is to lock the lens and prevent creeping I assume the other (marked "Conv" is to also prevent the rear element colliding with a converter, dont know if this applies to both the X2 and X1.4 tho'
Best bet would be to check the rearmost position of the rear element before fitting any lens to any brand TC

I remember buying a X3 converter for my Om30 for the Solar Eclipse, my 35mm lens had a protruding "flange" on the mount to prevent it been fitted to a converter due to its pronounced rear element.
Why cant Pentax do that?
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Mongoose

Link Posted 03/04/2007 - 23:15
I'm not sure about the 1.4x, but I know the Bigma can only be used from something like 100-500 with the 2x APO
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