p.1 #1Historical classic lens designs but in MFT mount. Any other interest out there?
I've have an interest in the history of lens design. I also own Micro Four Thirds cameras.
The lenses I've found so far that fit:
The Pergear 25mm f1.8. 5 elements in 3 groups. Barring the Ultron design I can't see why this isn't a Heliar design. It's a strange lens. Mine is sharp from wide open and has zero chromatic aberration. The build is terrible, the helicoid guides are not well made and there is wobble. The aperture closes down to F2 before going into the actual path of the lens. There is considerable veiling flare if the aperture is at that wide open point. The OOF rendering is the best I've ever seen on this lens. The OOF rendering and zero chromatic aberration all points to this being a Heliar design. It's also my least favorite aberration. There are no pictures of this lens design cross-section that I've found.
The new 10mm F3.5 7Artisans lens is a classic Biogon design 9 element in 7 groups. I have a copy of this lens coming.
The 21mm Kamlan f1.8 superficially looks to me to have a similar cross section of the venerable Lomo 7-28-1 cinema lens made in the former Soviet Union. This lens is sharp with excellent OOF properties. It also is well made with tight tolerances.
The 20mm f2 Vega-7, Vega-7E or Vega-7-1 is exceptional. This is a Xenotar lens design (Vega lenses are Xenotar designs). Sharp from wide open, low spherical aberration and the most incredible rendition Ive seen on a MFT lens. However, it does not cover an MFT sensor and only covers a bit more than a S16 sensor size. It's small, the front lens element is tiny, maybe 10mm give or take, the rear is smaller. It also requires needs careful adaption. I don't own this lens any more. It was a magical lens.
I've tried at least one Chinese 25mm lens out there with a double gauss design. Underwhelming. I also tried the 23mm TTArtisan with a concave front element that was also a non-starter in terms of adequate resolution and decent rendering.
There are chinese Sonnar designs with MFT mounts but generally are in the 35mm range and so of lesser general purpose use. The old 25mm F2.8 for Four Thirds cameras is a 5 element Planar design but reportedly has poor correction for spherical aberration and distortion.
My favorite lens designs are the 5 element Heliar, Xenotar and Planars.
p.1 #2Historical classic lens designs but in MFT mount. Any other interest out there?
The Voigtlander 25mm F0.95 is a complicated modern design and so does not qualify for this category. However, I thought it worth mentioning, this lens and the 25mm Mitakon/Zhongyi F0.95 (most likely a F1.2) are special lenses. The Mitakon/Zhongyi is also a modern but different design. It follows the modern Chinese fast lens practice of a standard lens design followed by a focal reducer to gain the lens speed. I've had four copies (don't ask why) of the Voigtlander and one copy of the Mitakon. As much as I love the modern Voigtander lenses I've used, the Mitakon is a better lens. Less chromatic aberration and sharper with decent rendering but probably a 1/3 of a stop slower. Half the size too.