Sigma 2x teleconverter on a Sigma 300/f2.8

Good morning All

I have a Sigma 70-200/f2.8 and a Pentax DA* 300/f4 which I am very happy with. However, I want greater reach and am getting tired of the wait for the Pentax 560.

I am considering a Sigma 2x teleconverter which would give me 400/5.6 on the Sigma 70-200 or possibly getting the Sigma 300/f2.8 which would give me a 600/f5.6.

Has anyone got/tried/rejected either of these options?

Regards

Eoin

2*K5, Sigma 10-20, 24-70, 70-200 and Pentax 300

I use to have a Sigma 70-200 and I have the DA*300.
And I have a 2x Sigma in the classifieds, used only for a few test shots.
With the 70-200 it is OK, but with DA*300(manual focus) is ruining the picture. DA*300 at 69% is better than DA300+2x Sigma.
I didn't have the DA*300 when I bought the converter.
Now I don't need or use it.

Regards,
George

Hi George - I have just noticed and commented on your 2x in the classifieds.

I am unsure about your last 2 sentences. The 'it' that is neither used nor needed is the DA300* or the convertor?

Would the IQ of the 70-200 used at 150 with 2x converter (i.e. 300) match that of the DA*300?

Regards

Eoin

Sorry Eoin,
The 'it' is Sigma 2x.
DA* 300 is my favourite lens in terms of optical qualities.

George

First of all which version of the 70-200mm f2.8 do you have?
If it is any of the HSM lenses then the Sigma 2x will not work on it.

I have the MKI (non HSM) 70-200mm and it takes the Sigma 1.4x well but the IQ with a 2x is not good and AF speed is pretty dire.

I can't comment on the Sigma 300mm f2.8 but I was using a Pentax A* 300mm f2.8 with the Pentax 1.7x adapter and the IQ was excellent. I sold the lens last week though to buy a Canon EF 300mm f2.8L IS and that is in another class entirely, with a 1.4x you don't get any loss of quality and I am now after a 2x for it.

BTW, if you put a 1.7x on the DA* 300mm you get pretty good results although you lose full AF.

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No equipment list here .... move along the bus please.

Hi Mike

Many thanks for the constructive info.

For the second time (at least) this morning I am confused because I have just been onto the Sigma Imaging site and their compatibility list for teleconverters/lenses definately shows that the Sigma 70-200 APO DG HSM has full auto focus in the Pentax mount. What am I misreading or missing?

Eoin

You are not missing anything apart from the fact the Sigma web site is wrong.

You cannot use a Sigma teleconverter with one of their HSM lenses. Pentax are so far down on their list of important things to do they can't even be bothered to change that list.

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No equipment list here .... move along the bus please.

Here is another list that seems correct. As you can see, no HSM lenses are listed under Pentax.

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No equipment list here .... move along the bus please.

Ditto, and similarly with the Sigma 100-300 F4.0 non-HSM (well, there isn't an HSM version - or anything available new - in PKAF anyway)
John

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West London - with a K-5, a K-R & some Sigma and Pentax lenses (and a lot of old 35mm gear!)

Hi All again

Apologies for the silence - I have been away. I have spoken with Sigma's technical department who do not inspire confidence. After several totally incorrect answers, they have confirmed what you have all said but seemed quite disinterested in updating their website to show the correct teleconverter pairings.

Perhaps a move to the dark side is called for especially if the best that Pentax can come up with for Photokina is a full frame camera.

Regards

Eoin