 Posted: Sat Feb 01, 2025 11:24 pm Post subject: pentax K 28mm f3.5 vs pentax K 30mm f2.8 |
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marcusBMG wrote:
Two plums from the pentax primes line up head to head - I acquired the 30mm last year and have intended to do this test since. Not quite a fair contest the K 30mm is suffering from a blotch of fungus on a rear element. But IME the main effect of that might be a certain loss of contrast.
My usual 28mm test subject of the castle from the south side. Frames nicely at 28mm on my K3-ii, I moved back about 10m with the 30mm to get similar framing. There is one click on the aperture ring between f3.5 and f5.6 on the K 28mm this seems to be halfway stop wise ie about f4.5.
Well the K 28mm 3.5 is certainly my best 28mm, though I must admit to more often having the kiron made vivitar 28mm f2, KA mount, on the camera. For me on these results the 30mm is in the same ballpark as good 28mm's I have taken test pics of the castle with - a good lens but not in the same class as the K 28. I find that almost all the 28's I have tried tend to show some field curvature with this subject, and the sides are softer. When I check focus in 10x live view and move the focus point on my K3ii to the side, I can sharpen the image by a small refocus at the expense of losing centre field focus by the same amount - that's field curvature, the plane of focus isn't quite flat.
However I must certainly try to clean out the fungus and check the results...
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pentax ME super (retired)
Pentax K3-ii; pentax K-S2; Samsung NX 20; Lumix G1 + adapters;
Adaptall collection (proliferating!) inc 200-500mm 31A, 300mm f2.8, 400mm f4.
Primes: takumar 55mm; smc 28mm, 50mm; kino/komine 28mm f2's, helios 58mm, Tamron Nestar 400mm, novoflex 400mm, Vivitar 135mm close focus, 105mm macro; Jupiter 11A; CZJ 135mm.
A classic zoom or two: VS1 (komine), Kiron Zoomlock... |
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