Today I'll be showing you some M42 screw mount lenses, and how they work
with Pentax cameras. Have three lenses with me today.
Have a 128mm F/2.8 Mamiya Sekor M42 mount. Screw type mount. Aperture
pin. There's an auto/manual knob you can change. The pin become spring-loaded
and it cycles the aperture. Not cycles... but it changes the aperture. Pretty
simple layout. Got your manual aperture control. Auto aperture setting. We don't
use that on current cameras, so just leave that in manual. You've got your focus
ring. This lens is pretty tight, so it makes it difficult to use.
I also have a Chinon 55mm F/1.7 this is my favorite M42 lens that I have. Nice
smooth... it's clean. Aperture works nicely. It's pretty rounded for an older cheap
lens. Also have a Mamiya Sekor 55mm F/1.4. Really rough, glass is
dirty. Aperture does work, but it's kind of... Not sure what I would call it. It's not
really close at all to being round. Probably changes as I cycle it.
Focus ring gets looser as I rotate it. Anyways, so we've got three M42 lenses
here. I have a Pentax *ist D camera body to use as an example. Of course, it's got the
K-mount. Have an adapter here this is the M42 to K-mount adapter. This is the
official Pentax one. It's got a metal piece here. That locks the adapter into
place once you rotate it. The pin will slide and then won't be able to rotate
until you push down on this metal. And then I'll show you an example. It's got
an orange dot. So orange dot to orange dot.
So it's in place. You have to rotate it.
That's locked in. See it won't move. To unlock it.. you've got that metal piece in there
you push down on it rotate it backwards. Pull it out.
So once I get this back in. Lock it into place...
It's locked down. Use the Chinon. All you do is rotate it until you can tell
that it's no longer going to move. Put your aperture into manual. You don't really
need to deal with that. Got your aperture ring. That's how you control that.
Focus ring...
Ahh, Pentax cameras... this is an older body, but all of them you'll get focus
confirmation. You know, the red dots in the viewfinder with manual lenses. This
is an older body. It doesn't have Shake Reduction, but all of the more recent
Pentax bodies have in.. in-body shake reduction. So with M42 lenses you'll get
--- shake reduction. Which is a great feature to have with, you know, older
thirty-year-old lens or something. You can also get catch-in-focus setting. So
what you do.. You'll put that catch-in-focus setting on. And you'll rotate your
focus ring and the camera will take a photo once it sees that the picture is
in-focus. Based on, I guess, I haven't used it much, but...
on whatever focus point.
So besides that, metering will work just fine with the M42 lenses.
So all you really need to care about is your aperture,
and of course your focus.