[sterretje]

I never carry a mix of m42 and k-mount. It's either the one or the other. So if I use m42, the adapter is permanently on the camera.

It might be a solution for your dilemma

[Na Horuk]

Hey there. K mount lenses will work on Pentax bodies. Of course, if the lens is from before AF was invented - it won't have AF. Same goes for other features, like transmitting lens info (focal length) or auto-aperture.
m42 lenses can be used if you have the adapter. you put the adapter on the camera and then you mount the lens. Then you can remove the lens and the adapter stays on the camera. Now you can mount another m42 lens, or you can remove the adapter. Note that the genuine Pentax adapter is easy to remove (just use your nail to push a little lever), but most if not all third party adapters require a tool to be removed. This makes them much less practical if you want to switch lenses.
Definitely read up on adapter threads if you are planning on using adapters or manual lenses. Adam linked to a good one, but there are a couple others. Its easy once you get it and you save many headaches if you read up first.
I think those lenses you listed will be great. Good luck

[johnyates]

I use a pair of vise grips to put the adapter on the lens thread just a little bit tighter than my fingers allow.

You can use a K-mount rear lens cap for this job as well.

[mikeodial]

You can use a K-mount rear lens cap for this job as well.

Thank you.

[Kozlok]

You can use a K-mount rear lens cap for this job as well.

I go just a smidge tighter than that. I tried to use a lens cap once, but damaged it with the sharp corners of my adapter.

[jatrax]

So I can expect to be removing and replacing the adapter in the field to use the combination of lenses?

Not if you use the Pentax adapter and leave it on the camera. The only lens I have that has the adapter afixed to the lens is my S-M-C 400mm. But I just consider it a k-mount now since the adapter is always on. For the bulk of my m42 kit, I use the Pentax adapter and only carry M42 lenses that day. I dislike mixing them, as the process is different and I don't like switching back and forth in the field. One bag has all M42 and the other bag is k-mount.

[mikeodial]

Not if you use the Pentax adapter and leave it on the camera. The only lens I have that has the adapter afixed to the lens is my S-M-C 400mm. But I just consider it a k-mount now since the adapter is always on. For the bulk of my m42 kit, I use the Pentax adapter and only carry M42 lenses that day. I dislike mixing them, as the process is different and I don't like switching back and forth in the field. One bag has all M42 and the other bag is k-mount.

Thanks. This seems like the logical way to go. I am sure I can work around it. Just bought a Domke F8 bag and seems I can bring all these M42 lenses in the bag without any trouble.

[canonguy]

I take a different strategy. I have a dedicted BODY for my screw mount lenses and its my K10. I leave the screw mount adapter in it all the time. The reasons are many, but to start with the K10 is not very good with ISO above 400 ISO in my opinion with too much noise, so using fast old primes (f2.0, 2.8 or f3.5) helps with keeping the ISO down. Autofocus also not real fast on K10, so manual focus lenses are an OK sacrifice here. Got the K10 used for only about $120.00 as my first Pentax DSLR, so not much point in selling it because its not worth too much. This is a great way to give it a purpose, namely, how good of an image can I get from a 10MP sensor? Or what kind odfa unique images can I get from quirky lenses like the JCPenny 200mm f3.3 or my Vivitar 50mm f1.7 VMC lens. but I also like KOZLOK's idea of the generic adapter on each screw mount - I considered doing that also and I may do that yet.