Sep 24 2014

DA40 XS on the Q


The Pentax Q has a tiny little mouse dropping of a sensor, 1/2.3″ (a measurement as clear in information as liters/100km would be to a horse that just found out he had one horespower)   What it means though is that it only has about 1/30 of the surface area of a 35mm film frame.  If you want to equate the field of views between those two disparate sizes while using the same lens you need to multiply the focal length by 5.6 on the Q.  In this case the DA 40 XS would wind up being the equivalent of a 224mm f2.8 lens on 35mm film.    And that is what makes this a neat little combination, it functions like a close focus telephoto and because the lens is so thin it fits the little camera nicely.  Another benefit of the small sensor is that it provides greater depth of field for a given aperture.  I know that sounds counter intuitive in this ‘thin is in’ shallow depth of field mad world but when you’re measuring it in millimeters having a little extra in focus without the need to stop the lens down can be a real advantage.  So not only is the DA40 XS a great lens on an APSc DSLR with an adapter  it fits nicely on the Pentax Q and here is another hint ‘it fits on a 35mm SLR’ too  Pentax-DA 40mm F2.8 XS on film.

May 2 2013

Pentax “Adapter Q for K Mount Lens”

I just picked up my Q to K-mount adapter so that I can use the lenses from my DSLR or Pentax K-01 as telephoto lenses.  The crop factor in terms of 35mm film for the Pentax Q is a whopping 5.5x.  What this means is that my 100mm macro becomes a 550mm equivalent lens.  Even a 50mm lens gives a field of view that a 275mm lens would on 35mm film or a “full frame” digital sensor.  When I choose to add photographic equipment I ask myself  “Does this expand what I am able to do photographically?”, the Q with this adapter certainly does provide me with something I didn’t have before.


I only had about an hour of fading light at a nearby park to make a few test shots but even in that short time I was able to see there are some new possibilities with compressing the view (extreme telephoto) and macro where the small sensor gives more depth of field.  All of this takes up very little extra room if you are already carrying the lenses for use on a camera with a larger sensor.   The limitations with the Q relating to its small sensor and high ISO performance are brought to the foreground with the need to use higher ISOs to achieve fast enough shutter speeds.  With further testing I’m sure I will find the point at which I can balance these competing parameters and achieve a result that I am happy with.  For now though here are images from my first foray into K-mount lenses on the Q.

I used the DFA 100 WR macro, the SMC Pentax-M 1:1.7 50mm and the SMC Pentax-A 1:2.8 28mm.