Teleconverter magnification - tested four.

Started Mar 23, 2014 | Discussions thread
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brandrx Forum Pro • Posts: 28,337
Teleconverter magnification - tested four.

Hi folks,

OK, so I did a test inside under a 75 watt tungsten bulb. I used four different teleconverters on a Pentax K-3 + Sigma 500/4.5 lens. Here is what I found out:

(1) Tamron-F 1.4X Pz_AF has the least amount of magnification. Note: I already know that my Kenko 1.5X Pz_AF has the same magnification as the Tamron-F 1.4X Pz_AF.

(2) Sigma 1.4X APO EX DG was just a very small amount greater than (1).

(3) Pentax 1.4X HD AW was just about the same magnification as (2). This one was the sharpest. I also had to dial in +0.7 EV to match the exposure of the other teleconverters.

(4) Promaster Spectrum 7 1.7X Pz_AF was greater than (3) and I already know that it is less then the Pentax-F 1.7X AF Adapter. So, I am going to assume that the Promaster 1.7X is really about 1.55X to 1.6X.

So, if (2) and (3) are in fact 1.4X then (1) must be about 1.35X or thereabouts.

The sharpness of (1), (2), and (4) are all about the same.

I also realize that this Sigma 500/4.5 doesn't do worth a damn under tungsten light.

I hope this helps some of you.

BTW: That Promaster 1.7X Pz_AF works great with the Pentax FA*300/4.5 lens. So, if that Promaster is really a 1.6X magnification that would give about a 480mm f7.2 lens.


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Pentax K-3
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