30mm m-lens

Well, first of all, the lens you mention is for a Leica that has a larger than usual sensor. So a 30mm lens on that system is not equivalent to the same focal length on a Leica M. It is wider.

A lens can be made smaller, but that usually involves a quality penalty. More highly corrected lenses generally have more elements. More glass means the mount has to be larger and longer to accommodate the bulkier optics. The use of aspherical elements is one way to reduce the size without compromising quality. Note for instance that many Zeiss lenses in ZM or ZF mount are larger than their Leica or Nikon equivalents.

If you want a 30mm lens on your M, use your 28mm and take one step closer!

A 30mm on the S2 should provide an angle of view equivalent to 24mm on a 35mm full frame camera, assuming dpreview is correct about the S2's 0.8 crop factor. This will help to give it a familiar feel to people used to using 24mm lenses on full frame; it isn't an oddball size the way 30mm on full frame would be.

I suspect the difference between 28mm and 30mm is so minimal that there really wouldn't be much of a market for a 30mm lens. I can't think of any 30mm lenses for full-frame. Sigma makes a 30mm f/1.4 for Canon, Nikon, and Pentax APS-C cameras, where (depending on the exact crop factor, which varies between brands) it gives an angle of view roughly equivalent to 45-48mm. I would guess they arrived at 30mm by scaling 50mm for Canon's 1.6 crop factor (50/1.6 = 31.25) and then choosing 30 as a nice round number that happened to be nearby.

I know what you mean. But do you know what I mean when I say "aspect ratio"?
If I used a 50mm you would have said, "just take 10 steps closer".
My point is...you can hypothetically tell the lens width used in most pictures.
And I hardly ever see 30mm shots but when I do see em, they are taken by D200 with a 20mm lens or something, but d200 has a 1.5 cropfactor, which makes 30mm in the 35mm realm. But somehow how I can tell 30mm pictures and like em more than 28 or 35mm angles. I do not know why, but I can see an aesthetic difference instantly.

and the proof of that be the same difference between you look at a 50mm picture and a 20mm picture...there is always a difference, so goes for 28mm vs 31mm.

That is one beautiful camera pictured above, especially after looking at photos of the new Nikon D4 with all it's bumps and outcroppings and switches and ports, etc.

That S series lens has '35' in yellow in the picture above.

A 30mm lens on a Leica. Hmmm. I am a sucker for odd focal lengths. It would need an external finder but could probably be used with the 28mm frames.

Now here is a thought. If you have an M8 your 24mm lens will equal about 32mm full frame. A 25mm lens equals just over 33mm full frame. That's kind of fun.
There are 30mm lens out there somewhere. They would require adapters and would be non-coupling. If you wanted them to couple you'd need the help from a good craftsperson.

The cheapest solution would be to take an itsy-bitsy, teenie-weenie step forward with your 28mm lens. But determining how itsy-bitsy and how teenie-weenie a step you should take and then doing it consistently could lead one to physical and mental damage. So I think the most cost effective and fun solution is to get an M8 and a either a Leica 24mm or Voigtlander or Zeiss 25mm lens. Then take an itsy-bitsy, tennie weenie step back to get the = of 30mm :-)

Assuming you're serious -- Pentax has been selling a 31mm lens for years.

"Assuming you're serious --"

If you mean me, I am always serious. I was thinking of that lens myself. With the Pentax 31mm lens being practically a 30mm, you could use it on the M9 or any Film M camera and you would not have to take an itsy-bity teenie-weenie step back at all, unless you were a fanatic perfectionist. There are Pentax to Leica adaptors available (I have two). I am sure some craftsperson could fashion a coupler that would turn the Pentax lens into an M lens and could also fashion an external 31mm finder. Wiith a few thousand dollars you could get the 30mm (+1mm) M mount lens of your dreams. It was probably cost less than an M8.

I seriously sympathize with people who have obsessive cravings. Right now I am obsessing over the Breiting Cosmonaute, which isn't made anymore and which I need as much as a dog needs a fifth leg. Worse, I am obsessive over a chronograph watch design of mine that would incorporate a 24 hour dial, a 24 tabulator and interchangeable bezels. I think compared to my obsessions, converting a 31mm lens into an M mount lens is a fairly easy and not outrageously expensive undertaking.

15mm Voigtlander on a Micro 4/3?