[mlt]

It looks like it has not been used in the last 40 years. It's basically the same size as the M50/1.7 (how did they manage?!) I will probably take it out for a spin later

An awesome find in that condition. You’re going to get a lot of questions when you take that beauty out, enjoy

[reh321]

It looks like it has not been used in the last 40 years. It's basically the same size as the M50/1.7 (how did they manage?!)

"Small", instead of "perfect", must have been a design criterion back then. Until recently, I didn't know that prime short lengths expected any thing much larger than a 49mm filter. Here are four lenses from my collection:
Zeiss Planar 50mm f/1.7
Pentax-A 50mm f/1.7
Pentax-M 28mm f/2.8
Vivitar(*) 28mm f/2.8

(*) the Vivitar lens was purchased my Mother for her FD-mount Canon camera

[Mistral75]

Nice!

Do these "compact" MILC systems even have lenses as compact as this?

(...)

There are two E-mount autofocus Samyang lenses that are almost as compact as the smc Pentax-M 20mm f/4 : the AF 24mm f/2.8 FE and the AF 35mm f/2.8 FE.

• smc Pentax-M 20mm f/4: 63mm x 30mm, 150g
• Samyang AF 24mm f/2.8 FE: 61.8mm x 37mm, 93g
• Samyang AF 35mm f/2.8 FE: 61.8mm x 33mm, 86g

[mlt]

One of the nice things about the M and A series primes is a common 49mm filter thread, just like the old SMC Takumars. My 28 f2.8A, M35 f2.0, M50mm f1.4, 50mm f1.7A, M85mm f2.0 and M150mm f3.5 can all use the same filter set - very convenient.

[phoebus]

One of the nice things about the M and A series primes is a common 49mm filter thread, just like the old SMC Takumars. My 28 f2.8A, M35 f2.0, M50mm f1.4, 50mm f1.7A, M85mm f2.0 and M150mm f3.5 can all use the same filter set - very convenient.

And FA 77/1.8 ltd and FA 43/1.9 ltd also keep with the 49mm filter thread. It just amazes me how glass is squeezed into the 77's tiny barrel!

[Class A]

And it would be tough to build comparable focal length and aperture lenses with such motors as compactly as the pre-F-series Pentax lenses.

While the motors and electronics add a bit of bulk, the size and weight of a lens is predominantly influenced by its "speed" and the requirements on optical quality.

Have a look at the Sony APS-C 20/2.8 lens which @Dipsoid mentioned. It is tiny(!) but features electronic aperture control and AF.

[reh321]

While the motors and electronics add a bit of bulk, the size and weight of a lens is predominantly influenced by its "speed" and the requirements on optical quality.

I believe “quality” primarily translates into “corner to corner sharpness”. My eight-element Takumar 50mm f/1.4 is no larger than any other 50mm of the Takumar - Pentax-A era.

[lsimpkins]

While the motors and electronics add a bit of bulk, the size and weight of a lens is predominantly influenced by its "speed" and the requirements on optical quality.

Have a look at the Sony APS-C 20/2.8 lens which @Dipsoid mentioned. It is tiny(!) but features electronic aperture control and AF.

Yep, that Sony sure is tiny. The A series Pentax 20mm/2.8 is quite a bit larger, especially in length. Then, as you note, there are only 6 elements in the Sony compared to 10 in the Pentax which looks to be a major contributor to the size difference. And when Pentax went the AF route with the FA version of the lens, it stayed basically the same size - nothing added for the screw AF drive.

[Cynog Ap Brychan]

I recently picked up the Pentax-A 20 mm f2.8, which isn't a big lens by any means, though it does flare out at the end to a 67mm filter size. I gather from reading the above posts that the Sony is smaller, but it is an APS-C lens, which would give a 30 mm field of view, so comparisons are not really in the same ball park. For a reasonably similar field of view on APS-C, the 15 mm f4 Limited is a tiny lens, though if it was f2.8, it would be a whole lot bigger.

[noelpolar]

Can still buy a new 20mm Voigtlander..... Hong Kong Buy and Sell Limited

Probally the smallest 20 around. Very DA15ish in my view.... similar compromises but ff. Ive got over 3 years of use with it so far on my K1.

[Ascencio]

Pentax will be very well placed in L alliance with bodies having specific Pentax touch, stabilized sensor, WR, astrotracer, etc. plus other specific implementations only for ML, at a price close to K1. To begin a lens kit 24-105 / 3.5-5.6 or 24-70mm / 4 will be sufficient, at an acceptable price, they will be enough. In the meantime, enough lenses from Sigma or Panasonic will be available. Then they will be able to adapt existing optical formulas from K to L. If Panasonic will be optimized for video, Leica for those who have a lot of money, Pentax will be optimized, as now, for outdoor photography. The market will be bigger than if they ventured alone in the ML realm.

Absolutely would be perfect marriage
Keep the motor for screw mount lenses in the adapter

[climbmountainway]

The Canon D90 shows the viability of an APSC DSLR over its mirrorless counterpart (the M6II) as a well equipped and fully functional video camera. The new Pentax flagship APSC can bring Pentax up to date with a video dock and outboard rig system, with lighting, audio, and video extended features (e.g. mechanical-electronic tracking support) controls for the Inde filmmaker already adapting Pentax glass to existing video camera bodies.

[reh321]

The Canon D90 shows the viability of an APSC DSLR over its mirrorless counterpart (the M6II) as a well equipped and fully functional video camera. The new Pentax flagship APSC can bring Pentax up to date with a video dock and outboard rig system, with lighting, audio, and video extended features (e.g. mechanical-electronic tracking support) controls for the Inde filmmaker already adapting Pentax glass to existing video camera bodies.

The D90 came out only recently, too recently to determine how it will do.

I'm not sure what you picked the M-6ii - my understanding is that the M-50 has been "carrying Canon's water" in the APS-C MILC category for the year, and right now B&H still shows it as better seller than both the M-6ii and the D90.

[Ascencio]

Yup, I've tried the Sony A7ii, the A7iii, the Nikon Z and the Canon EOS R. They all hurt my eyes.

Get a new eye

[MarkJerling]

Get a new eye

Quite happy with my eyes thank you. I've never had any problems with my eyes when looking through my Pentax camera viewfinders.