Pentax K to Q-mount Adapter

Image Quality Tests

In order to gauge the true reach of the Q with the adapter, we started by performing a simple test.  We put the same lens on the Pentax K-5 (16.3 megapixels, APS-C) as on the Q (12 megapixels, 1/2.3") and then shot the same scene.  We scaled the resulting images for comparison.  The Q photo is the one on the left, while the K-5 photo is on the right.

The Q is the clear winner in terms of detail, and this difference is even more apparent when you view the two images in full size (Q full-size link, K-5 full-size link).  Note that the photo from the Q suffers from a great deal of chromatic aberration; we believe that this is due to diffraction and its small sensor size.  We have scaled both photos to a width of 1024 pixels.  Both photos were taken with the SMC Pentax-M 80-200mm F4.5 lens.

In order to see just how well the Q fared, next we faced it off against a somewhat tougher opponent.  We opted for the M 80-200mm on the Q because we wanted to keep the cost of the setup as low as possible. You'd be surprised how sharp this $60 lens can be!  Here are the results of the Pentax Q setup ($560 value) vs the Nikon D800 and the 70-200mm F2.8G VR II lens ($5400 value).  Both lenses were set to 200mm.

While the Q isn't quite as sharp, you're certainly getting much more than $560's worth in terms of image quality (D800 full-size link).  Our next comparative photo confirms this:

Again, there is a little more detail in the D800 file, but the Q holds its ground very well.  Keep in mind that we're using a $60 lens here!

Next we wanted to see if a premium lens mounted on the Q could close the gap a little bit more, so we took Pentax's equivalent of the Nikon lens: the FA* 80-200mm F2.8, and we put it on the Q.

Here, the difference isn't quite as big, but the value of the Q setup has also been bumped up to some $2000.  The key advantage of the DSLR in the particular shot is its better dynamic range and color depth.

Lastly we performed a comparison using the exact same lens: a life-sized macro with the Sigma 150mm F2.8.

Based on what we've seen, we'd say that for $560 you're getting about $3000 worth of image quality.  Not bad for a point-and-shoot sensor!

All photos featured on this page were developed from RAW files and taken at minimum ISO.  For best results with the Q, be sure to shoot at low ISOs.

The Bottom Line

The Pentax Q can come close to the image quality of a full-frame DSLR at a fraction of the price when using telephoto lenses with the same focal lengths.  Because the Q doesn't offer autofocus and has no viewfinder, however, it is no replacement for a professional wildlife or landscape setup. Despite this, for those who can afford to take their time when composing the shot, the Q with an adapted (D)SLR lens is a superb (and reasonably-priced) telephoto solution.  The only issue which the Q can't get around is that it doesn't give you the freedom to play with depth of field: using small apertures is not advisable becuase of diffraction.  Apart from this, you can be confident that the Q will be able to outperform any current Pentax DSLR when paired with the same telephoto lens.

The Q adapter has two weaknesses that you should keep in mind, though.  First, it's not of much use for wide-angle shots (even a fisheye lens turns into something along the lines of a telephoto), and the Q's small sensor would end up becoming a bottleneck anyway. Second, at longer focal lengths, composing your photo (or even finding your subject) can be very difficult.  The same goes for focusing.

Fortunately, there's a solution for the former problem.  Either get an optical viewfinder, or mount a spotting scope/red dot sight, as forum member Shawn67 has done here:

If you have a Weaver rails to hotshoe adapter (sold through third parties), we recommend using the Pentax Gameseeker RD10 red dot sight with the Q or Q10.  It really makes the camera easier to use with long lenses.  Alternatively, even a small optical finder will work better than live view in some cases.