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Old Nov 25, 2011, 7:09 PM   #1
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Default The Q + DA 55-300 and DA 18-250

Hi All,

After waiting a few days longer than expected for my new K to Q adapter with aperture control, I finally got some sunshine to test it with the DA 55-300 and DA 18-250.

The day was starting to cloud over by the time I got to the Nature Center, so I didn't have as much time as I had hoped.

I started with the DA55-300 at 300mm. I could tripod mount this as my Tamron SP 80-200 f2.8 tripod ring fits the lens pretty well. I was also using my new 2.8x LCD loupe to give me some help with focusing. My only real concern was to get the focus correct, so forgive the compositions and poses. . . I was sitting on a bench about 20 feet away from a small tree off to the side of some of their bird feeders. All shots, except where noted were only downsized in steps with no other PP applied.

To give some perspective, this is from the same spot with the 47mm EQ Q prime, so it's essentially as seen by the naked eye. This was taken on a previous outing.

Pentax Q, DA 55-300 @ 300mm (1650mm 135 EQ), f5.8 , 1/400, ISO 320.

Pentax Q, DA 55-300 @ 300mm (1650mm 135 EQ), f5.8 , 1/500, ISO 320

Pentax Q, DA 55-300 @ 300mm (1650mm 135 EQ), f8 , 1/160, ISO 320

Pentax Q, DA 55-300 @ 300mm (1650mm 135 EQ), f8 , 1/125, ISO 320.

This is the same shot with my normal sharpening drill, maybe a touch too much. . .

Pentax Q, DA 55-300 @ 300mm (1650mm 135 EQ), f5.8 , 1/320, ISO 125

I switched to the DA 18-250, which doesn't fit in the tripod ring, so I got about 10 feet closer to the squirrel, and shot handheld, first at 18mm (99mm 135 EQ) to give some perspective.

DA 18-250, 250mm (1375mm 135 EQ),f6.3, ISO 125, 1/320 handheld

Here's the same shot with my normal sharpening drill

I'm really impressed! The JR K to Q adapter works great, and the aperture control is needed for the DA lenses as they have no aperture ring on the lens. The aperture control ring has six indents in between the two ends of its rotation, and since on every Pentax lens since the A series the aperture control lever on the lens is linear -- meaning for each stop, the lever moves the same amount -- each of the indents pretty should pretty accurately produce one stop difference in aperture.

Of course with the tiny sensor, diffraction will start to soften the image as you stop the lens down past f5.6, but as you can see with the shots at f6.3 with the 18-250, and at f8 with the 55-300, one can get away with shooting stopped down some, then bring it back with some PP.

Since these are consumer grade lenses, though they are both good ones, I hope this might illustrate how the Q can be used as a digital TC with some pretty good success.


Last edited by snostorm; Nov 25, 2011 at 7:15 PM.
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Old Nov 27, 2011, 9:27 AM   #2
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Interesting results - the camera does show the limitations of the two consumer lenses (I've also found the 55-300 somewhat soft at 300 when compared to the prime *300 lenses - it's not a fair comparison). It's nice to see that the pictures can handle post processing without falling apart. The bird really does come out nicely when sharpened.
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Old Nov 29, 2011, 4:31 AM   #3
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Stunning results, thanks for sharing them

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