Help ... advice on m42 extension tubes

Godfrey DiGiorgi gdigiorgi at
Mon Jul 19 18:09:40 EDT 2010

On Mon, Jul 19, 2010 at 11:47 AM, Sam L <samthegreat at> wrote:
> I was perusing the pentax forum marketplace and saw an add for pentax
> m42 extension tubes for $15.
> They seem to include 12, 20, 36mm.
> Here's a photo:
> I am clueluess about extension tubes but have heard plenty of people
> say they use them for doing macro work.
> I'd like to have the ability to play around and do some macro stuff.
> Is this an appropriate set?  Good price?  Are there limitations I
> should be aware of?
> I'll be mounting them to my k-x via the pentax m42 adapter.  Someday
> maybe I'll mount them to a spotmatic.
> Would I be way better off getting a set up k-mount tubes?

The real question, Sam, is "What lenses are you going to use the
extension tubes with? What sorts of subjects do you intend to

There's no point to buying M42 threaded extension tubes if your lenses
are all Pentax K bayonet mount. Extension tubes work best with
symmetrical and mild telephoto lens designs.

I highly recommend reading John Shaw's excellent book "Close-ups In
Nature" before buying any macro equipment.


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