Originally posted by reh321 Are you certain that a prime wide angle would have to be large?
For film, no, you can get away with pancakes
like the Pentax M20/4 or Voigtlaender Color Skopar 20/3.5.
But a good modern interchangeable extreme wide-angle lens
has to send the rays vertically down to the sensor,
which means a big reverse-telephoto design.
Then you probably need internal focusing
with moving groups small enough to work well with autofocus,
and pretty soon your lens is as complex as any zoom,
so why not make it a zoom anyway,
so you don't lose resolution by cropping?
Originally posted by reh321 I have a 28mm Pentax-M lens, and it is smaller than my 50mm Pentax-M lens
Those are from the film era, and we're talking about lenses that are way wider than they are.
Originally posted by reh321 I have refused to buy the Q-mount 08 (which also costs serious money) because one lens like that is more than enough for my budget, but I would be more than happy to buy a 4.2mm/4.4mm prime lens if it were priced "comparably" to the 01 standard prime
The patented wide Q primes look like they'll cost as much as the 08 zoom,
with their advantage lying in their speed.
If you want a cheap wide angle for the Q,
you'll probably need to adapt a surveillance or old cine lens.