Teleconverter Question

[andrew_wilson5]

Can anyone tell me what a 1.7x teleconverter will do to my 50mm

1:1.4 lens. It will turn it into a 85mm 1:???. Can someone do the

math and get back to me?

[markku_ylilammi]

Just multiply both the focal length and max. aperture value by the teleconverter multiplicand.

 

1.7x converter makes 50/1.4 into 85/2.4

[maxpometun]

If you are talking about Pentax brand 1.7x converter and have a manual focus 50/1.4, in addition to lens extension you will get autofocus.

[yeow_teng_kuah]

I don't quite get it what do you mean by "If you are talking about Pentax brand 1.7x converter and have a manual focus 50/1.4, in addition to lens extension you will get autofocus". You get real auto focusing of the lens?

[maxpometun]

Andrew, sorry for such a late reply.

Yes, you will get a real autofocus on any Pentax AF camera body. Pentax 1.7x converter is actually called "SMC Pentax-F 1.7x AF adapter". It not only multiplies the length of the lens (and the aperture) by a factor of 1.7, but also converts any manual focus lens into autofocus one. AF is achieved, I believe, by moving the whole optical system inside the barrel of the converter. Effectively, you are attaching a moving rear element to your lens.

So, if you have MF 50mm F1.4, with SMC Pentax-F 1.7X AF Adapter attached you will get an 85mm F2.4 autofocus lens (assuming you have an autofocus camera body).

[maxpometun]

I'm sorry, my latest reply was intended for Yeow Teng Kuah.

[slawek_jacek]

Question to Andrew:

 

How do you find the combination of 1.7x teleconverter with 50mm 1:1.4 lens?

 

I expect to get my 1.7x TC soon. Having 50/1.4(M) and 50/1.7(A) and 28-105/3.2-4.5 zoom, I consider dropping my 100mm/3.5

 

I am more interested in good bokeh and contrast/colour aspects than in absolute sharpness.

 

Thanks