[RioRico]

This question arrived in a PM and I think it's worth exposure.

I'm throwing this at you because I'm pretty sure you know the answer and it doesn't seem to warrant a forum question.

Is there any difference between mounting a M42 lens onto M42 extension tubes and then an adapter to the camera body, vs. mounting the M42 lens via the adapter onto K mount extension tubes? If not, then having one set of K tubes should be sufficient?

Well, there is *mostly" no difference between mounting a screwmount lens onto screwmount extension which is mounted via adapter to the camera, and mounting the lens on an adapter onto PK tubes mounted on the camera. Like this:

lens -- M42 extension -- adapter -- camera
vs
lens -- adapter -- PK extension -- camera

So you'd think that one adapter and one set of tubes would be enough. But life is more complex. Some factors:

1) For longer lenses, just one set of tubes, even with bellows attached, won't be long enough to achieve much magnification. I need bellows plus several tube sets for close usage of 160-190mm enlarger lenses. Luckily, tubes are very cheap.

2) Various cheap M42 tubes from different sources, and the standard cheap PK tubes, may be of different thicknesses. I often use thin tubes to rather finely adjust the focus ranges of some lenses, and sometimes 1mm can make a difference.

3) Not all M42 tubes have the same depth of threading. This means I can put a mid-range enlarger lens on a deep-thread tube and have some focusing ability, rather than be stuck with a fixed-focus. Thus I keep several different sets of M42 tubes.

I also have several sets of standard cheap PK tubes. These are useful for more than just macro work. I may glue a tube and mount to a wide projector or copy lens body, using those as a cheap PK adapter, to be mounted on PK bellows. That's how I manage to use some exotic (and cheap!) Schneider and Rodenstock and Extar lenses. Other lenses with odd or no mount threads can be adapted by drilling a hole in a cheap thick black PK or M42 body cap, then inserting the lens, and mounting it on extension. But sometimes gluing a tube to the lens body is the only trick that works.

I find that some lenses need my heavier PK bellows and tubes, and some are just fine with the lighter-weight M42 extension; and some REQUIRE one system or the other to get the right fit. If you just want to put an M42 lens on extension for general close work, then the answer to your question is, "No difference". If you want to use a wide range of lenses in curious ways, then it's good to have more gear.

[Jean Poitiers]

Bonsoir RioRico,

Thanks ... good info and worth the post and should be an article/sticky IMO. I had the same basic question, too ... picked up a Super Tak 55/1.8 and was thinking about some tubes, etc., in order to experiment.

Salut, J