Pentax-01 Standard Prime 8.5mm f/1.9 (Pentax Q) - Review / Lens Test
Lens Reviews - Pentax Q

Review by Klaus Schroiff, published November 2011


The release of the Pentax Q system produced some rather mixed reactions in the "blogosphere" - mostly regarding the small sensor size (1/2.3") of the camera. However, even so it remains a mirrorless system so we will provide some basic coverage here at

As of the time of this review the system offers 5 lenses - two "kit" lenses, a fisheye lens and two "toy" lenses. This review will focus on the Pentax-01 Standard Prime 8.5mm f/1.9. The first thing that we'll get used to is the focal length here. APS-C or micro-four-thirds lens specs are more or less familiar among "serious" users but 8.5mm sounds odd here. This relates to the size of the camera sensor which has a crop factor of 5.5x so in full format terms we are talking about "47mm" thus a standard lens. Now this is not the full story. The max. aperture of f/1.9 sound fast and it is terms of light gathering. However, if you apply the cropping factor (f/1.9x5.5 = ~f/10.4) things will appear not all that sexy anymore regarding the depth-of-field potential. You can still achieve some basic object isolation with this lens but only if you move very close to your subject.

The build quality of this tiny lens is very good. The outer barrel is made of some kind of alloy although the inner construction is made of plastic (plus the glass elements, of course). This results in a weight of merely 36g! THIS may give you an idea about the sense of the system - it is primarily about extremely small size and low weight. Even the smallest micro-four-thirds cameras and lenses are big in comparison. The focus ring operates smoothly with no wobbling whatsoever.

The focus speed of the lens is pretty fast - after all there's little to move anyway. Manual focusing is often difficult because the Pentax Q offers a max. focus magnification of just 4x which makes it difficult to judge the accuracy of your focusing actions - this is not so much a problem of the lens but of the camera. However, the focus-by-wire mechanism of the lens doesn't make things any easier here - there's also no distance scale.

Equiv. focal length47 mm (full format equivalent)
Equiv. aperturef/10.4 (full format equivalent, in terms of depth-of-field)
Optical construction8 elements in 5 groups inc. 2x UD elements
Number of aperture blades5
min. focus distance0.2 m (max. magnification 1:20)
Dimensions45.5 x 23 mm
Weight36 g
Filter size40.5 mm
Hoodbayonet mount, optional
Other featuresSP coating

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