[hangu]

This is a picture of Kindai M42 adaptor. It is more precisely machined than Pentax one. Its inner flange depresses the stopdown pin of some M42 lenses that do not have auto/manual lever. It costs about $100 or more.

It looks like it requires a tool to remove. That's a deal breaker in my book.

[pacerr]

Adding shims would be similar in effect, although miniscule, to adding an extension tube I guess!

Correct. As long as the shims do not act as a spacer between the lens seating surface and the body the only adverse effect could be clearance between internal parts - but that's rare.

The flanged M42 adapters act as a very thin (~ 0.8mm) extension ring preventing infinity focus. The flange serves to provide a surface for the lens latching notch. If you remove the flange so the outside diameter of the adapter is less than the inner diameter of the camera mount it has no effect on focus.

I've modified a number of 'em over the years. A very tiny dab of silicon seal, acrylic finger nail polish or rubber cement on the lens threads and on the lens base acts as a semi-permanent friction surface between the mounts to help secure the lens so it doesn't tend to unscrew as you focus. It's an economical way to convert M42's into K-mounts without damaging them.

H2

[Nesster]

... sounds to me like the adapter's threading is done 180 degrees wrong. Are you sure you're putting it onto the K mount in the right orientation (I've never tried to put one in in an alternate orientation, so I don't know if this is even possible.)

I have a Rikenon M42 that seems to have come out of the factory with a screwy mount - it goes on 90 degrees past 12 o'clock noon, on every camera / mount I have. With real screw mount cameras this puts the aperture pin way off from the mechanism that depresses it. With a K adapter it's not too bad, but the damn lens lacks the A/M switch. It came with a thin shim on it, which eliminated infinity.

[sherwood]

I have a Rikenon M42 that seems to have come out of the factory with a screwy mount - it goes on 90 degrees past 12 o'clock noon, on every camera / mount I have. With real screw mount cameras this puts the aperture pin way off from the mechanism that depresses it. With a K adapter it's not too bad, but the damn lens lacks the A/M switch. It came with a thin shim on it, which eliminated infinity.

Out of the factory ? Of course, if you bought it new. But if it was second hand... who knows ?

A used Helios-44M I bought on ebay, despite being in good condition, had one day been "serviced" and reassembled the wrong way. 180° off ! It was usable on my DSLR, but with the markings on the bottom...

It took me +/- 1 hr to open, clean, lube and reassemble the lens properly. Now it focuses a bit past infinity. It wasn't deliberate, but now I can get infinity focus even with a flanged adapter.

I'd like doing this with my MIR-1V, because the rear of this lens is so narrow that it only seats on the Pentax adapter. As there's no friction on the camera body, it's easy to unmount the lens accidentally (I removed the screw and spring from my adapters) !
With a flanged adapter, the lens is clicked as a k-mount one. But it doesn't focus to infinity.

[Nesster]

I figure it was so from the factory as the three screws holding the mount are locked in, I've tried a couple of times to loosen them... and at any rate, re-setting the thing will only give me 1/3 turns, and I'm not certain the aperture pin will work. One of these days, I say...

[frank]

I've used quite a number of different M42 to PK adapters, so far my favorite is this one:

Another M42 to PK Adapter - 黎环 - ClubSNAP Photography Forums

It fits better than the Pentax original, and you don't need a tool to remove it. It's kinda like a modified Kindai version mentioned above.

[ddhytz]

I've used quite a number of different M42 to PK adapters, so far my favorite is this one:

Another M42 to PK Adapter - 黎环 - ClubSNAP Photography Forums

It fits better than the Pentax original, and you don't need a tool to remove it. It's kinda like a modified Kindai version mentioned above.

Interesting. I notice in your post you said "One thing though, this '黎环' doesn't come with the spring to lock the lens in position when mounted, it only keep the lens in position by friction force. So it's only suggested to use the adapter with shorter focal length lenses (anything below 135mm) or some lenses with very stiff focusing ring. "

Judging by "friction force", "shorter focal length", and "stiff focusing ring" it seems a bit risky to use it.

One concern is that this adaptor may get stuck in the body one day. If that happens how do you take it out?

[titrisol]

I think this is correct; I also got a few of these cheapo adapters and have the smae problem
There is no way to put the adapter in the camera at 180 degrees I think.

... sounds to me like the adapter's threading is done 180 degrees wrong. Are you sure you're putting it onto the K mount in the right orientation (I've never tried to put one in in an alternate orientation, so I don't know if this is even possible.)

I have a Rikenon M42 that seems to have come out of the factory with a screwy mount - it goes on 90 degrees past 12 o'clock noon, on every camera / mount I have. With real screw mount cameras this puts the aperture pin way off from the mechanism that depresses it. With a K adapter it's not too bad, but the damn lens lacks the A/M switch. It came with a thin shim on it, which eliminated infinity.

[titrisol]

BRILLIANT!
where can I buy one?

I've used quite a number of different M42 to PK adapters, so far my favorite is this one:

Another M42 to PK Adapter - 黎环 - ClubSNAP Photography Forums

It fits better than the Pentax original, and you don't need a tool to remove it. It's kinda like a modified Kindai version mentioned above.

[m42man]

It fits better than the Pentax original, and you don't need a tool to remove it. It's kinda like a modified Kindai version mentioned above.

I must take issue with phrases such as "more precisely machined than the Pentax..." and "fits better than the Pentax...".

The whole point of the Pentax adapter design is that it is a loose fit INTENTIONALLY. In fact, it's VERY accurately made, such that the looseness is lost as you screw the lens onto the camera.

It's because of this that it's the only type of adapter (except for the flange type) which definitely never need a tool to remove it.

You only lose out with this adapter if you use it with certain lenses which have a slightly raised lip, which fits within the diameter of the adapter; in this case, the lens will tighten onto the adapter, but not the camera mount, so you're left with the original adapter looseness.

I have a couple of such lenses, but it's relatively easy to make up a plastic shim of the correct dimensions (the most important being the thickness!).

[patolds]

Ahhh, very wise!

A sort of not-too-permanent locktight to secure the thread....why didn't I think of that! BRILLIANT!!!

Turn the flange off the adapter...now that gives me ideas!!!!

Thanks and cheers

Paddy

[Nesster]

I have a similar adapter with the inside flange to hold the aperture pin in. It works, but does have some of the usual issues third party adapters generally have.

If you look carefully at a proper K mount lens, and the Pentax K adapter, you'll see the bayonet tongues are not symmetrical, nor are all 3 the same. Most 3rd party adapters have these tongues symmetrical and identical, with slopes on each one. This is why they don't lock in well, and why they can turn too far in the camera.

[frank]

Interesting. I notice in your post you said "One thing though, this '黎环' doesn't come with the spring to lock the lens in position when mounted, it only keep the lens in position by friction force. So it's only suggested to use the adapter with shorter focal length lenses (anything below 135mm) or some lenses with very stiff focusing ring. "

Judging by "friction force", "shorter focal length", and "stiff focusing ring" it seems a bit risky to use it.

One concern is that this adaptor may get stuck in the body one day. If that happens how do you take it out?

It's not risky at all. As a matter of fact, I took off the spring even when I was using the original Pentax M42 adapter. It's far easier to use w/o the stopper spring.

First of all, it won't stuck in the body if used as I described. Secondly there are two tiny holes on the edge of the ring for you to put tool in so you'd be able to 'turn' it out of the body if really need to .

BRILLIANT!
where can I buy one?

I bought from China. If you want, I got a couple spare ones left (ordered for local Pentaxians, but a couple of them never came to collect)

I must take issue with phrases such as "more precisely machined than the Pentax..." and "fits better than the Pentax...".

The whole point of the Pentax adapter design is that it is a loose fit INTENTIONALLY. In fact, it's VERY accurately made, such that the looseness is lost as you screw the lens onto the camera.

It's because of this that it's the only type of adapter (except for the flange type) which definitely never need a tool to remove it.

You only lose out with this adapter if you use it with certain lenses which have a slightly raised lip, which fits within the diameter of the adapter; in this case, the lens will tighten onto the adapter, but not the camera mount, so you're left with the original adapter looseness.

I have a couple of such lenses, but it's relatively easy to make up a plastic shim of the correct dimensions (the most important being the thickness!).

Well, I've used many adapters including the original ones from different eras, I have to say the original Pentax adapters aren't the best out there, other than you don't need a dedicated tool to remove it from the camera body

[agraspar]

Make sure you source a genuine Pentax K mount adapter. Part number 30120.

Where would it be best to buy the K mount adaptor online? Thanks in advance!

[stevebrot]

Where would it be best to buy the K mount adaptor online? Thanks in advance!

Google "pentax 30120"


Steve