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Pentax Adapter K for 6x7 Lens (6x7 to K Mount) Review RSS Feed

Pentax Adapter K for 6x7 Lens (6x7 to K Mount)

Reviews Views Date of last review
4 27,851 Mon December 23, 2019
Recommended By Average Price Average User Rating
75% of reviewers $120.75 9.50
Pentax Adapter K for 6x7 Lens (6x7 to K Mount)


This is an adapter allowing you to use Pentax 6x7 mount lenses on K-mount bodies, including DSLRs as well as film SLRs.

You will have to use stop down metering as the adapter neither has aperture contacts nor an aperture stop down lever.

Pentax Adapter K for 6x7 Lens
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Light Loss
0 stops
0 elements, 0 groups
Mount Variant (Rear)
Mount Variant (Front)
Inner/Outer Bayonet
Weather Sealing
Diam x Length
Production Years
(in production)
User reviews
This adapter allows for mounting Pentax 6x7 lenses on a K-mount camera.
The only exposure modes supported are M and Av with stop down metering, and Bulb. The adapter has no aperture stop down lever and no lens information contacts.
Full-Frame Support
Price History:

Add Review of Pentax Adapter K for 6x7 Lens (6x7 to K Mount)
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Loyal Site Supporter

Registered: September, 2017
Location: Medellín
Posts: 1,286
Lens Review Date: December 23, 2019 I can recommend this lens: Yes | Price: $160.00 | Rating: 10 

Pros: Build quality, compatibility.
Cons: No tripod mount.

Build quality is top notch, tight tolerances, as you would expect from Asahi. The only downside I have found is that it doesn't have a tripod mount. For shorter lenses, not really a problem, but for longer ones without a tripod mount it gets cumbersome and I really prefer not to exceed its design limit with a longer lens like the 67 300/4 with the camera being the one mounted on a tripod. I'd rather use it handheld with one hand under the lens, the other on the camera.
All in all, longer lenses always have a tripod mount which also allows the barrel around it to rotate for portrait or landscape orientation, so I would trade this option on the adapter with a tripod mount. Or having the option of both.
Site Supporter

Registered: July, 2017
Location: Cinco de Mayo
Posts: 511
Lens Review Date: March 5, 2018 I can recommend this lens: No | Price: $98.00 | Rating: N/A 

Pros: Strong Build.
Cons: Be aware for the "Incompatible Version"

Editorial note: this user reviewed a version of the adapter with a Nikon lens mount

BE Carefully: I buy this adapter and I found INCOMPATIBLE with the K mount on modern cameras. Maybe this version needs a diferent review.

I think that this will fit in earlier K mount devices, but in my K3II, KX, ME, SF10 and SFX the adapter simply DOES NOT FIT.

After reviewing the adapter and comparing the frame of other lenses, I verified that the distance that separates the inside of each tooth from the bayonet is narrower in the adapter than in the lenses; that why It stuck and cannot be twisted any longer tha a few milimeters.

For clear indentification of this variant, this adapter has a tiny SCREW in the side of the bayonet mount, has a level, and the RED dot in the K mount side is very small.

Giveaway winner!

Registered: December, 2007
Location: beantown
Posts: 944

3 users found this helpful
Lens Review Date: December 7, 2011 I can recommend this lens: Yes | Price: $135.00 | Rating: 9 

Pros: Handy on smaller format to run full open
Cons: no tripod mount

I originally wanted to mount my 300mm on a K body, but I soon realized that I was also gaining the sharpness towards the center in the processes for any 6x7 lens. This works out even better when I need to photograph indoors with dSLR in poor lighting and prefer low ISO for maximum resolution or just the option to have max aperture and still have edge to edge or corner to corner goodness to work with. I've had people say a good digital lens will do the job, but to have a sweet spot that is 3/5 or 1/3 of the frame is usually achieved at f5.6 or smaller. My 105mm will give mostly the entire frame area on a APS-C a maximum resolution and at f2.4 or a modest cost of f2.8 to push it. Yes, this has been an amazing tool to reach for in quite a few assignments. I suppose some of those third-party version will be as good and with a tripod socket, but I will say that I'm comfortable just bean-bagging for now and knowing this is factory perfect fit to my collection of gear.
Inactive Account

Registered: September, 2009
Location: SoCal
Posts: 1,292

2 users found this helpful
Lens Review Date: November 29, 2010 I can recommend this lens: Yes | Price: $90.00 | Rating: N/A 

Pros: Well built, all aluminum/steel
Cons: Necessarily large

My Pentax K mount to 6x7 adapter is labeled:
Ashai Pentax Japan - Adapter K for 6x7 lens

The construction is very good and is all metal and reasonably light weight. The adapter's larger maximum diameter clears the penta prism on my LX and K 20D fine. I have only used it with one larger 6x7 lens (Tak 135 macro) and the assemby with extension tubes is very well attached to the camera body. There is no lens system in this adapter, it is basicaly a spacer/adapter that allows for the full focus range.

In the mid section of the adapter is a large knurled knob. By rotating this you release friction on the barrel and the lens attached can be fully rotated. There are four detent positions built in at 90 degrees for vertical and horizontal. Possibly some 6x7 lenses have a rectagular stray light shield in the rear of the lens. The 6x7 helicoid extension accessory does. I assume this rotation system is to align that as well as the lens aperature adjustment to a handy position or a tripod mount equipped lens.

Using the adapter with a digital or film body you will be on full manual. There are no electrical contacts or aperature fingers.

The 6x7 lenses attach using a three tab bayonet system similar to the k mount. The adapter also has a male bayonet ring on the outside major diameter using four tabs. In the 5 and 7 o'clock positions on the major diameter in the above picture, the male bayonet tabs can be seen.

There are aftermarket adapters available which might be of lesser quality. One illustration did show a boss in the center section I assume might be for a tripod mount. Unconfirmed; I do not believe the afternarket adapters have the so called 'outer bay' lens extension tube mount for the 400MM and up lenses.

I aquired this adapter because I had a nice 6x7 Takumar 135 macro lens. Using it has been fun as the big lens is just a great thing to focus and use in spite of the size and weight (suprisingly light). This also will allow use of all the other 6x7 glass available. The digital body with the adapter and Tak 135 lens is a very solid mount but the size makes it all a bit unhandy as a walk around. That would be about the same as a mid-size tele lens.

Regarding the external bayonet mount flanges. There are special 6x7 lens extension tubes illustrated in the Accessory section that apparantly attach to them. These are used to improve the close focus ability of longer 6x7 tele lenses above 400mm.

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