Pentax PK Adapter same as M42 ?

[mcwidi 2]

First post. I have a M43 Panasonic Lumix G2 and recently purchased a lens on eBay that I want to adapt to the G2. The lens is a (Pentax) Asahi SMC Takumar 55mm 1.8 with a screw type mount. The lens also has a switch that can be set at MAN or AUTO. Before I purchase an adapter I need clarification as to weather or not a Pentax PK adapter is the same as an M42? Also should the switch on the lens be set at MAN or AUTO? Thanks for advice or comment.

 

[Aoi Usagi]

No, they are two different mounts. M42 is the screw mount and the PK mount is a bayonet mount .

 

[Lightshow]

First post. I have a M43 Panasonic Lumix G2 and recently purchased a lens on eBay that I want to adapt to the G2. The lens is a (Pentax) Asahi SMC Takumar 55mm 1.8 with a screw type mount. The lens also has a switch that can be set at MAN or AUTO. Before I purchase an adapter I need clarification as to weather or not a Pentax PK adapter is the same as an M42? Also should the switch on the lens be set at MAN or AUTO? Thanks for advice or comment.

You will need an M42 adapter, with the later lenses, there can be some issues with mounting and causing binding if the adapter has a flange at the bottom of the adapter that is to depress the pin, IME it's because the opening is too narrow, a round file will take care of that, you can spot the issue when the aperture ring won't turn, and focus is stiff, and possibly a gap between the mount surfaces.

If your adapter has the flange, it won't matter which setting you choose, but if the adapter has no flange, then you will have to set it to the manual setting to be able to adjust the aperture, also not every M42 lens has an auto/man switch, so if you plan to buy more M42 lenses, I'd get the one with the flange.

 

[Tom Caldwell]

First post. I have a M43 Panasonic Lumix G2 and recently purchased a lens on eBay that I want to adapt to the G2. The lens is a (Pentax) Asahi SMC Takumar 55mm 1.8 with a screw type mount. The lens also has a switch that can be set at MAN or AUTO. Before I purchase an adapter I need clarification as to weather or not a Pentax PK adapter is the same as an M42? Also should the switch on the lens be set at MAN or AUTO? Thanks for advice or comment.

You will need an M42 adapter, with the later lenses, there can be some issues with mounting and causing binding if the adapter has a flange at the bottom of the adapter that is to depress the pin, IME it's because the opening is too narrow, a round file will take care of that, you can spot the issue when the aperture ring won't turn, and focus is stiff, and possibly a gap between the mount surfaces.

If your adapter has the flange, it won't matter which setting you choose, but if the adapter has no flange, then you will have to set it to the manual setting to be able to adjust the aperture, also not every M42 lens has an auto/man switch, so if you plan to buy more M42 lenses, I'd get the one with the flange.

All good advice,

But as a beginnner - as far as I know the internal flange that automatically pushes in the rear pin on a lens so equipped to allow aperture control from the camera was a later invention by (Chinese?) adapter manufacturers who for want of a name have called it a "pin pusher" - it certainly overcomes the problem of those M42 lenses that don't have a MF/AF switch that had to have some sort of mechanical intervention to mechanically hold the pin shut or to have to jam the mechanism in some way.

Early MF lens adapters found a way to easily keep the pins of their Helios-44 lenses of a type depressed without need of a pin pusher ledge - if anyone needs to know this let me know and I will tell all.

Some early M42 lenses before MF/AF types that were purely MF with no pins to hold shut have a deeper inner mount flange which extends beyond the pin pusher flange and will not mount properly on the M42 adapter so equipped. If the pin pusher flange can be removed then this would cure the problem - but as many adapter manufacturers have not anticipated this removal process the pin pusher washer leaves an inner gap which makes registration distances using the grub screws alone flakey to say the least. A well made adapter should have a machined fixed inner ledge that will still operate after a pin pusher washer is removed. Otherwise the only recourse is to find a smaller internal diameter flush-fitting washer to replace it. These are usually made out of unobtainium.

Luckily these lenses are relatively few. I have a very nice early Enna Tele-Ennalyt 135mm f3.5 that is made that way. Luckily I had an early bought M42-LM made without pin-pusher that I could dedicate to this lens.

 

[mcwidi 2]

Thanks for sharing your knowledge and expertise.