UPDATE! Pentax 55mm f/2.8 lens hairline scratches
Related: Pentax, Pentax 645 D FA 55mm f/2.8 AL[IF] SDM AW, Pentax Lenses, Pentax medium format
See previous post below.
According to Pentax (and my estimation of Pentax just went up for owning up to it):
We have noticed some similarities in our DA 645 55mm AW lens. It appears to be very small disturbances (apparently in the optical adhesive between elements). However, this does not affect performance. In fact, this lens has produced outstanding images that were enlarged to 3'x4' with no anomalies.
I have no doubt that the design is capable of outstanding images, but (in general) whether each and every physical sample of any particular optical design is also capable of its potential is not a defensible claim, as proven by my own experiences. No manufacturer can build the same design in quantity without variation.
A follow-on note:
We also noted some microscopic particulates. Still, no performance problems. (It could be that your Nikon and Zeiss lenses use different materials and element groupings).
This I think is harder to justify. The lens has a slight but visible haze, which is not going to help contrast. If I can see it, then it’s in the image the lens projects to the sensor.
Several things should be noted:
- "this lens" means the lens(es) Pentax used, not the lens I have (and one wonders if such lenses were cherry-picked). Every sample varies from every other. What Pentax has observed could be a non-issue with their sample(s), but could be an issue with the one I have. If I can see something, then so can the sensor.
- I intend to look for issues by shooting into the sun and with strong backlighting situations. These scratch-like patterns catch the light (that is how I can see them!), so the question is whether they show up in real images or not. That all depends on where they are in the optical path.
- The apparent haze that I see could lower lens contrast. I still don’t have the camera, so I cannot shoot samples to see how this plays out. But I don’t see this haze effect with my Nikon or Zeiss lenses.
I have another sample on the way from B&H Photo, and that will prove instructive.
