K3 III / D FA 150-450 with/without Pentax 1.7x AF converter

Hello

I made today test pictures with my K3 III and the D FA 150-450 with and without the Pentax 1.7x AF converter.

I used the LV AF:

@ 450mm and without the converter:

now I set the K3 III to the 1.7x crop mode:

this picture has only 8.9 MP, instead of the 25.73 MP's of the sensor.

now with the 1.7x AF converter (and of cause the camera use not it's own 1.7x crop mode)

this picture has of cause the 25.73 MP of the sensor, but I did uploaded a smaller one.

and now I compare a zoom in:

I can not simple use a 100% view, because the 100% view of an 8.9 MP picture show still much more of the scene as a 100% view of a 25.73 picture do show, therefore I used for both a same frame in LR:

a frame from the 1.7x camera crop mode picture (it has not so much pixels) :

and a frame from the 1.7x AF converter picture:

I, personally, see no IQ lost do to the use of the 1.7x AF converter, but I get with the 1.7x AF converter the 25.73 MP's of the sensor, meanwhile the camera's 1.7x crop mode has only 8.9 MP.

Conclusion:

With the 1.7x AF converter I get the full sensor MP's, while the 1.7x camera crop mode ends up with 8.9 MP's. Well, 8.9 MP's aren't that small, but they're quickly lost if you want to enlarge the image in the PP. Then the 1.7x AF converter shows its strengths, as you can work with the full sensor MPs in PP for enlargements. On the other hand, there is also a limitation for the 1.7x AF converter, the resolution of the lens itself. The D FA 150-450 with the aperture open, for example, no longer has much reserve to continue to enlarge an image with the 1.7x AF converter in the PP, because the IQ decreases quickly. This looks completely different if the lens has a very high resolution. For example, my F* 300mm f4.5 has a large resolution, and then I can continue to enlarge images with the 1.7x AF converter in the PP and the IQ still remains good

best regards KPM2