Pherdinand, you have a good point & I may have been too hasty in responding. Wider lenses are more compact than standard lenses, so the 40 mm length should help make it more compact than a 50 to begin with. I was reacting to the definition of compact in the post: "as compact as the 35/2.5 pancake II."
That Voigtlander lens is only 23 mm long!
Let's look at the length of some Leica lenses:
35/2 = 34.5 mm
35/1.4 = 46.2 mm
50/2.8 = 37.6 mm extended/21.6 mm collapsed (storage position)
50/2 = 43.5 mm
50/1.4 = 52.5 mm
To make a 1.4 lens of longer focal length (40 mm) as compact as an already compact 2.5 lens (1.6 stops slower) of shorter focal length (35 mm) would be a miracle IMHO.
To build a lens just one stop faster (1.4 vs 2), Leica had to increase the length about 20 - 25% on both the 35 & the 50 - with the greater increase on the wider angle lens, which is the one closer in focal length to the rumored 40.
If Cosina could build a 40/1.4 at the same length as the 35/2. I think that would be remarkable. But as you point out, this would still be quite compact.
Cosina has accomplished miracles before, so I'm prepared to be duly impressed. However, until I actually read some facts, you'll have to consider me to be a doubter on this rumor.🙁
