[dadengler]

I've been using vintage lenses on my KP and I need clarification on something. I've searched this forum and elsewhere and tried vintage lenses on my camera. The catch-in-focus works with manual k-mount lenses but not m42 mount. Is that correct? Was that the same on the old K-3?

[scc]

Hi,
What I experienced with my K7 and a K 300mm f/4 manual lens is as follows:
With the K7 set for AF with focus priority, the shutter will not trigger unless the lens is in focus, which behaves like a “catch in focus”. Since the focus confirmation should not depend on the type (M42 or Kxx mount) but only on the phase detection of the AF system, it should work with the M42.
To my opinion of course.

[pschlute]

I've been using vintage lenses on my KP and I need clarification on something. I've searched this forum and elsewhere and tried vintage lenses on my camera. The catch-in-focus works with manual k-mount lenses but not m42 mount. Is that correct? Was that the same on the old K-3?

Your issue may be with the conductivity of the M42 lens mount. The camera needs to know a lens is mounted.

Detail the lenses that don't work.

[Not a Number]

As I recall most K-mount bodies need the pins on the body shorted out for catch-in-focus to work. One solution that I've seen is to take a piece of thin metal like an aluminum beverage can. Make a collar/ring that will cover the pins on the camera mount and remove any coatings on the collar down to bare metal.

If the barrel of the body is wide enough to cover the pins either remove the paint/coating on the rear of the lens that comes in contact with the pins. Or use a bit of metal foil.

[AnotherVoice]

As I recall most K-mount bodies need the pins on the body shorted out for catch-in-focus to work. One solution that I've seen is to take a piece of thin metal like an aluminum beverage can. Make a collar/ring that will cover the pins on the camera mount and remove any coatings on the collar down to bare metal.

If the barrel of the body is wide enough to cover the pins either remove the paint/coating on the rear of the lens that comes in contact with the pins. Or use a bit of metal foil.

Shorting out stuff hasn't been my experience. I own the KP and Catch-in focus works like a champ.

[pschlute]

Shorting out stuff hasn't been my experience. I own the KP and Catch-in focus works like a champ

Which lenses ?

[mlag]

As I recall most K-mount bodies need the pins on the body shorted out for catch-in-focus to work. One solution that I've seen is to take a piece of thin metal like an aluminum beverage can. Make a collar/ring that will cover the pins on the camera mount and remove any coatings on the collar down to bare metal.

If the barrel of the body is wide enough to cover the pins either remove the paint/coating on the rear of the lens that comes in contact with the pins. Or use a bit of metal foil.

Happens mostly with lens mounts or adapters that are painted/coated black. Should not be a problem on blanc metal ones...

[dadengler]

Your issue may be with the conductivity of the M42 lens mount. The camera needs to know a lens is mounted.

Detail the lenses that don't work.

Works (shutter fires when it reaches focus): SMC Pentax-M 50/f1.7, Helios 77K-4 50/f1.8, both are manual K mount.

Only beeps and focus indicator lights up when in focus (shutter fires regardless of focus): Super Takumar 50/f1.4, Super Tak 35/f3.5, SMC Takumar 55/f1.8, all are M42 mount.

Actually the K-3 does the same thing. I must be missing a setting.

Note: All of the contacts on the camera are visible with the M42 lenses.

---------- Post added 11-20-23 at 03:48 PM ----------

Shorting out stuff hasn't been my experience. I own the KP and Catch-in focus works like a champ.

On K-mount or M42?

[kypfer]

Note: All of the contacts on the camera are visible with the M42 lenses

That's exactly the problem ... without the contacts shorted the camera doesn't know there's a lens mounted so it won't perform catch-in-focus and will release the shutter irrespective.
In circumstances like this, assuming infinity focus isn't required, using one of the cheaply available "flanged" M42-PK adaptors, with the paint/coating scraped off to allow the contacts to short out, will allow catch-in-focus.

[Mikesul]

To clarify, Catch in Focus will work with all K mount lenses. No need for shorting. That was only necessary with the older lenses like M42.

[dadengler]

That's exactly the problem ... without the contacts shorted the camera doesn't know there's a lens mounted so it won't perform catch-in-focus and will release the shutter irrespective.
In circumstances like this, assuming infinity focus isn't required, using one of the cheaply available "flanged" M42-PK adaptors, with the paint/coating scraped off to allow the contacts to short out, will allow catch-in-focus.

Thanks, I was just hoping there was a back door work around in the menu somewhere. I wonder which are the two contacts that need to be shorted? Otherwise, the flanged adapter is probably the best idea, that or steadier hands on close focus.

[UncleVanya]

Thanks, I was just hoping there was a back door work around in the menu somewhere. I wonder which are the two contacts that need to be shorted? Otherwise, the flanged adapter is probably the best idea, that or steadier hands on close focus.

Flanged loses infinity focus.

[dadengler]

Flanged loses infinity focus.

That's why I only have the Pentax and K&F adapters. I guess I could just use a tripod when using close focus and wide open or maybe use K-mount lenses for that.

[kypfer]

Thanks, I was just hoping there was a back door work around in the menu somewhere. I wonder which are the two contacts that need to be shorted? Otherwise, the flanged adapter is probably the best idea, that or steadier hands on close focus.

I seem to remember it's the "seventh" contact, the one closest to the a/f screw-drive, that needs to be shorted to ground (one of the pins is also a ground), but I'll admit to just sanding away any coating in the general area until catch-in-focus works. Using a suitable metal tool on the lens-mount contacts on the camera (nothing sharp that might damage the gold-plating) it'll take just a few seconds to establish which pin needs to be grounded so's the shutter button won't release the shutter
Bear in mind catch-in-focus becomes unreliable (or doesn't work at all) once the lens is stopped down much below f/5.6 ... can be an issue with M42 lenses that (obviously) won't have auto-aperture on a K-mount camera or, indeed, with any pre-set (T2-mount) K-mount lenses.

[Not a Number]

I seem to remember it's the "seventh" contact, the one closest to the a/f screw-drive, that needs to be shorted to ground (one of the pins is also a ground), but I'll admit to just sanding away any coating in the general area until catch-in-focus works. Using a suitable metal tool on the lens-mount contacts on the camera (nothing sharp that might damage the gold-plating) it'll take just a few seconds to establish which pin needs to be grounded so's the shutter button won't release the shutter

Yes, it is only the "data" pin that needs to be shorted, though it does no harm electronically to sand a larger area. After all bare metal non-A lens cause no problems.