Sony-P67/645 Pentax-A SMC 120mm F4 macro 1:1

There is a first time for everything, and this time I got my hands on a cheap secondhand P645 120mm F macro at the used market of CP+ in Yokohama.

I got mine for about 12.000 yen, ($120) but can generally be had on ebay for about $200~

Mine came without lens hood, but I had a spare 67mm filter thread metal lens hood lying around. The lens is 700g (without lenshood, adaptors etc) It has super smooth focusing, and a really long focus throw which comes in hand when trying to focus with in macro photography as the depth of field is ridiculously narrow.  The barrel also extends really far at 1:1 magnification.
With the crop factor on FF it works out to about 180mm FOV.

And hand holding this beast in the wild is close to impossible at f4 @ 1:1 even with the Sony IBIS The super thin DOF shown below when testing close focus is something like 1mm

Test setup

Here is what I am doing to try and get comparable results. I.e consistent setup

First off:

  • Level and 90degrees shooting for even length to focus plane and the setup.
  • Same framing for all lenses. I.e longer focal length will be shot from further away to achieve same framing. (see images below)
  • Lighting is done by softbox and flash to eliminate any motion-blur.
  • ISO50 for low noise, 1/200sec shutter and exposure adjusted through flash.
  • Shot tethered into CaptureOne Pro 9, with only White balance, CA and Crop adjustment - No additional sharpness added. exported to 100% quality Jpeg in sRGB at 2048px wide.

Sharpness test

Above shots are f4, f8, f11, f16, f22, f32

Below is a 100% crop for pixel peeping, please open the image in a new window or download to see in full size.

Already wide open at f4 the image is pretty sharp, but above that the image just gets better, and at f22 light diffraction starts to set in on the FF sensor, and at f32 the image is pretty soft.

Closing thoughts

Really sharp once stopped down below f5.6 until f11 and really fun to use, but for handheld shot you really need a tripod or a flash setup. Certainly it is well worth the $120 I paid. :)

It really is a challenge to keep focus at the focal length with such a narrow DOF, and I often found my breathing was enough to throw off focus. But it was quite rewarding to use the lens and also good practice, and I will likely use this lens more in the future for other projects.

Check out the real life gallery below for macro and non-macro examples.


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