Originally posted by Jasvox Forgive me if this has been asked already or if its a sore subject....but I am going to ask anyway...
1, Will older Pentax lenses work on a full frame camera, if Pentax launches one, someday? I know some older lenses aren't recommended for APS-C sized cameras, just wondering if any older ones are FF compatible?
2, Which current, newer generation lenses designed for DSLR will also work with full frame? I know there some out there, but who knows which ones?
Jas
1) Any pre-DA series lens was designed to fill the 35mm frame. Consequently, any pre-DA series lens would presumably work with the aforementioned imaginary 'full frame' Pentax DSLR -- as 'full frame' means the image sensor would comply with the size of a 35mm film frame.
2)DA lenses are 'supposedly' designed for the smaller APS-C (also an antiquated film size) sized sensor -- which would cause the edges of the image frame to darken if used on a camera that uses 35mm film or a sensor the same size as a 35mm frame; this is called vignetting.
All lenses suffer from some degree of vignette -- but the effect would be greatly pronounced in a lens that projects a smaller image circle than the size of the sensor (or film frame) designed to record it.
3)Some people, claim that many DA lenses do in-fact project an image circle that will accommodate the larger 35mm frame. I don't know anything about this question. As I don't have a film camera or the will to test such things. But some people do, and they will probably reply with their experiences. Furthermore, as far as I know, Pentax doesn't release the size of the image circle that each lens produces.
4)DA lenses also 'supposedly' have extra coatings on the rear elements to reduce flare. . as in a film camera the film absorbs the light. In a digital camera, much of that light just bounces off the sensor -- causing imaging problems. Tho I have never seen nor experienced such phenomenon with any pre-DA lenses that I have ever used on my camera. This attribute is unrelated to the size of the sensor.
5) Pentax lenses break down like this:
M42, K, M, A, F, FA, and DA.
[M42, K, M, A] manual focus [F, FA, DA] auto focus
[M42, K, M, A, F, FA] 35mm frame [DA] APS-C frame
any revisions from those in the know are welcome!