With M42 you can use Av metering. It's better to
test first to see if you need to set +/- compensation for that
aperture. They are usually consistent from f/4 to f/16

For focus with M42 it's better to set the lens at f/5.6 or wider
so that you can focus at that aperture. A lot of zoom lenses are
f/5.6 wide open anyway. This is more accurate than focusing wide
open and then stopping down especially with top glass because
there is usually a focus shift. Sonnar types do this more than
others.

With 24,28mm or 35mm I find it better to set the lens
at infinity and and f/8 and leave it there....
everything from a few meters to infinity will then be
sharply in focus.

-

You stand a better chance of consistent exposure with any
lens that doesn't rely on mechanically closing the diaphragm
and is already at working aperture. Once you know the T Stop
of an M42 lens at say f/8 it will always be that value, even
if grease gets on the blades. So no excuse for wrong exposures
there

I've just used an old M 35mm f/2.8 at f/8 and every exposure
was different the iris must be sticky, but it looks fast enough.

I've tried to remove the mount to clean inside but 3 of the 5
retaining screws are stuck solid. Pentax used a funny size
cross head as well so hard to find an exact small screwdriver
to fit them. I thought I'd cracked it when a largish
TengTools PHOx75 fitted exactly, because I could get good
torque with that I couldn't believe it when it
sheared the point/tip off the screwdriver

TengTools have a lifetime Guarantee and they say you are OK
hitting the screwdriver with a hammer.

That looks quite impressive I see what you mean about how
it would be difficult for BIF, but any long BIF work needs a
gimbal type mount to not be awkward

Don't forget that there's also an excellent Russian Jupiter 9
in M42 quite cheap SH for anyone wanting 85mm f2 link

Ponds Cold Cream and lighter fuel.
See theses pages.

link

link

Lapwings aren't that easy to catch in flight and the one that you
have posted is reasonably sharp and shows the wings quite well.

The Grebe shot is nice and sharp and well captured considering
that these don't usually come close to people.

There was some stuff about telescopes for bird photography on the
US forum. I think it was a thread about lenses longer than 300mm

2 mins later:

This is the thread link I had it bookmarked at page 74..... that might
be the last page I read? I've looked back to page 70, but can't
find the details of the telescope so it may be prior to that

Nice sharp shots It always make me wonder why telephoto
lenses are so expensive when telescopes are often sharper and
cheaper to buy

I think Mattmatic has a Pentax-FA 24-90mm for sale

All you need is for someone to state on a website that:
"Your the best wedding photographer in the world today"
and they'll all come flocking to you

Well it works with photographers and lenses!

Don't forget to buy a 'Cat Carrier' only $16.49 link