Originally posted by lytrytyr Those lenses are all available in the native Pentax M42 mount:
ZEISS Large Image Format Lenses | Industrial Lenses
---------- Post added 07-22-17 at 10:29 PM ----------
Zeiss rate both the 25/2 and 25/2.8 the same on their sharpness scale,
good for a 3.4 micron pixel size at 30% contrast.
lytrytyr, from your statements above, I strongly suspect you don't own any of the modern Zeiss "Classic" lenses.
First, on my two Pentax K1 cameras, the Zeiss f/2 is noticeably sharper and more detailed than the Zeiss f/2.8 lens that I owned for years and used on the same "
REAL WORLD" test subjects. Your response is typical of someone whose only experience with either of these lenses is a quick Google search and finds an obscure laboratory test to prove your point. I'll take real world results on the very camera that I shoot with any day over lab tests that were not done using a Pentax K1 camera.
Here's what the premiere independent lens tester (
Roger Cicala) in the USA has to say about the sharpness of the Zeiss 25/2 lens:
"In terms of pure resolution it’s superb, generating numbers in our testing similar to the legendary 21mm f/2.8. Sharper than the Nikon or Canon 24mm f/1.4 lenses when shot at f/2.0. Sharper than any 35mm, 50mm, or 85mm lens we stock at f/2.0. And that’s both in the center and overall (weighted average) sharpness. But there’s a bit of a catch: that’s for testing at middle distances (10 to 25 feet). But at infinity (where the MTF charts are made) it doesn’t seem quite as good (it’s still good, but not amazingly good)." Second, I am certainly aware that Zeiss makes these lenses in the M42 mount. Zeiss ZF lens (Nikon Mount) in the Nikon mount are much more available on the used market than are the rarer Zeiss ZS (M42 mount) lenses.
For years I have watched Ebay auctions on Zeiss ZS (M42 mount) lenses. I have only found the following three versions Zeiss Classic lenses ever on sale on Ebay - 25/2.8, 35/2, and 50/1.4. The Zeiss 25mm f/2 lens that this thread is focused on has NEVER been available on Ebay to my knowledge in the ZS (M42 mount).
For the last few years, both Adorama and B&H have sold only two Zeiss ZS lenses - 25/2.8 and 35/2. Both of these lenses were also made by Zeiss in the Pentax K mount, so why would a K1 shooter ever want to buy one of these two Zeiss lenses in the M42 mount?
I have never seen a Zeiss 25/2 lens in M42 mount offered for sale by either a major retailer or on Ebay. That makes me doubt if any ZS mount 25/2 lenses were ever made by Zeiss. If you think I'm wrong - please show me where I might buy a Zeiss 25mm f/2 lens in M42 mount.
P.S. I have shot dozens of M42 lenses on my K1 cameras. I have used them on a variety of M42 - K adapters (including various genuine Pentax versions). The M42-K adapters I have owned are flimsy/weak compared with Leitax adapters. Further, Leitax adapters are stronger and better made than any of the dozens of Zeiss lens mounts I have held and examined. When it comes to choosing the tightest and most secure mount for my expensive (and often heavy) Zeiss lenses, I purposely choose Leitax mounts over both M42-K mounts AND Zeiss mounts.