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Carl Zeiss 50mm f1.4 Planar T* ZK lens on Pentax K1 DSLR
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PostPosted: Tue Feb 20, 2024 2:04 pm    Post subject: Carl Zeiss 50mm f1.4 Planar T* ZK lens on Pentax K1 DSLR Reply with quote

Clever people,


I'm considering getting a Carl Zeiss 50mm f1.4 Planar T* ZK lens (Pentax K mount).

The lens being manual focus, I'm in doubt if it will "communicate" exif, priority & shutter values to the camera body on a K1?

I have its 'cousin', the Milvus 50mm makro planar with my Nikon D3 where all values are passed on to the camera, so I would assume it's the same with th K mount version even if it's an older model, but would like to have this confirmed before buying.

Put another way, I have a Pentax 77mm limited lenses, one of my all time favourites. I assume the Carl Zeiss will function the same way in all manners except being without the autofocus feature?


Huge thanks in advance,

Kasper


Last edited by kasperbergholt on Fri Apr 05, 2024 10:34 am; edited 1 time in total


PostPosted: Tue Feb 20, 2024 5:05 pm    Post subject: Re: Carl Zeiss 50mm f1.4 Planar T* ZK lens on Pentax K1 DSLR Reply with quote

kasperbergholt wrote:
Clever people,


I'm considering getting a Carl Zeiss 50mm f1.4 Planar T* ZK lens (Pentax K mount).

The lens being manual focus, I'm in doubt if it will "communicate" exif, priority & shutter values to the camera body on a K1?

I have its 'cousin', the Milvus 50mm makro planar with my Nikon D3 where all values are passed on to the camera, so I would assume it's the same with th K mount version even if it's an older model, but would like to have this confirmed before buying.

Put another way, I have a Pentax 77mm 1.8 limited lenses, one of my all time favourites. I assume the Carl Zeiss will function the same way in all manners except being without the autofocus feature?


Huge thanks in advance,

Kasper


This should be covered in the K-1's owners manual booklet.
I'm not a pentax user, so no easy answer from here.
I did have a D-200 which is a similar time frame to the pentax, and the exif data could be manually entered as above.

-D.S.


PostPosted: Thu Feb 29, 2024 5:07 pm    Post subject: Re: Carl Zeiss 50mm f1.4 Planar T* ZK lens on Pentax K1 DSLR Reply with quote

Doc Sharptail wrote:
kasperbergholt wrote:
Clever people,


I'm considering getting a Carl Zeiss 50mm f1.4 Planar T* ZK lens (Pentax K mount).

The lens being manual focus, I'm in doubt if it will "communicate" exif, priority & shutter values to the camera body on a K1?

Huge thanks in advance,

Kasper


This should be covered in the K-1's owners manual booklet.
I'm not a pentax user, so no easy answer from here.
I did have a D-200 which is a similar time frame to the pentax, and the exif data could be manually entered as above.

-D.S.


Hello again,

I ended up getting the 35mm f/2 instead of the 50mm 1.4. There seems to be different generations of the different Zeiss classic lenses with KAF mount - some with an 'A' setting an some without. I got the first - and there's communication between camera & lens after setting the focal length (which the camera identified as '35'mm). In essence, it works like my 7mm 1.8 lens but without autofocus.

It's a fine piece of engineering.


Last edited by kasperbergholt on Wed Dec 25, 2024 5:53 pm; edited 1 time in total


PostPosted: Mon Dec 09, 2024 3:01 am    Post subject: Re: Carl Zeiss 50mm f1.4 Planar T* ZK lens on Pentax K1 DSLR Reply with quote

This post reflects several misapprehensions about both Zeiss lenses on Pentax as well how the various K mount versions work.

First, it's important to realize that there have never been any Zeiss lenses released in the "KAF" (K Autofocus) mount, and that includes Jena, Oberkochen, or licensed Japanese-made lenses. There are only K mount lenses (no contacts/A setting) and KA (with contacts/A setting). These are the first and second versions of the K mount respectively. KAF is up to its fourth revision, but no Zeiss lens has ever used any of them.

Secondly, claiming that A lenses "communicate" with the body or carry "data" is technically accurate, but only in the barest sense.

K mount lenses have exactly one active data pin, and it communicates exactly one binary value of on/off. When you turn the ring to the A setting, it's "on," and all other values are off. That's it.

Now, you might also notice cutouts with plastic inserts on the base of your KA lens as well. These use a simple passive scheme to encode two more values: max and min aperture of the lens. That's it.

Things they don't communicate: aperture values, focal length, focus position, flash metering information, lens ID, or for that matter, EXIF of any kind. If you open the lenses up you won't find ANY chips, encoding brushes, advanced electronics, or the like. Literally everything is handled camera-side with no other active communication with the lens. This is true of all lenses using the KA mount, including original Asahis, the Zeiss lenses in question, and even brand new lenses from Samyang, Irix, etc.

How do these lenses work, then? The answer is standardization. On every KA lens, the position for the aperture actuation lever on the lens for any given aperture value is always exactly the same. The body just needs to know the encoded aperture values to know where it's starting from when computing exposures based on a wide open reading and how far it can stop the lever down. All other things being equal, every lens with this type of mount is treated exactly the same by the body.

The earlier K mount with mechanically coupled aperture did not have these standardized positions. Aperture values were communicated by a separate mechanical lever, while the actuation lever is pushed down as far as it can go on every exposure, with its travel limited by a mechanical cam in the lens. In fact, on KA lenses, it works exactly this same way in any setting but "A"!

On later KAF bodies, including most Pentax DSLRs, the mount was "crippled" to remove support the mechanical communication lever, which is why turning the aperture ring on them doesn't update any information camera side on your K-1, and without the encoding on the lens mount, it will have no clue about either max or min apertures. You can still use the green button to stop down meter in M mode, but wide open metering is out for obvious reasons.


kasperbergholt wrote:
Doc Sharptail wrote:
kasperbergholt wrote:
Clever people,


I'm considering getting a Carl Zeiss 50mm f1.4 Planar T* ZK lens (Pentax K mount).

The lens being manual focus, I'm in doubt if it will "communicate" exif, priority & shutter values to the camera body on a K1?

Huge thanks in advance,

Kasper


This should be covered in the K-1's owners manual booklet.
I'm not a pentax user, so no easy answer from here.
I did have a D-200 which is a similar time frame to the pentax, and the exif data could be manually entered as above.

-D.S.


Hello again,

I ended up getting the 35mm f/2 instead of the 50mm 1.4. There seems to be different generations of the different Zeiss classic lenses with KAF mount - some with an 'A' setting an some without. I got the first - and there's communication between camera & lens after setting the focal length (which the camera identified as '35'mm). In essence, it works like my 7mm 1.8 lens but witouth autofocus.

It's a fine piece of engineering.