Agreed, less compromises in their design.

It would be interesting to see some images from that 20 1.4 taken stopped down. That lens would appear to be second in the batch so presumably there is at least a #0 and a #1 somewhere. I wonder how many more and where they might be hiding.
Shame the known example is in the hands of someone who doesn't even use a Pentax and hasn't bothered to obtain one to use that jewel of a lens, instead sticking it on a cheap adapter.
Hope he hasn't taken out the click stops and aperture lever as some on this site might have done to lenses they own!

If anyone's trying to complete a full set, this list includes to my knowledge, all known K & M variants.

Asahi Pentax (K) Series
8.4mm F2.8 Fish-eye
8.4mm F2.8 Bird's-eye (Prototype)
15mm F3.5 (AL) (SMC PENTAX 1:3.5/15) (distance-scale in feet is … 7 4 2 1.5) (1975)
15mm F3.5 (SMC PENTAX 1:3.5/15) (distance-scale in feet is … 7 3 2 1.5) (1975)
15mm F3.5 (smc PENTAX 1:3.5 15mm) (distance-scale in feet is … 7 3 2 1.5) (1977)
17mm F4 Fish-Eye
18mm F2 ED (Prototype)
18mm F3.5 SMC PENTAX 1:3.5/18 (early variant),
18mm F3.5 smc PENTAX 1:3.5 18mm (later variant)
20mm f1.4
20mm F2 ED (Prototype)
20mm F4
24mm F2.8
24mm F3.5
28mm F2
28mm F3.5
28mm F3.5 Shift (SMC PENTAX SHIFT 1:3.5/28 ) (1975)
28mm F3.5 Shift (smc PENTAX SHIFT 1:3.5 28mm) (1977)
30mm F2.8
35mm F2
35mm F3.5
50mm F1.2
50mm F1.2 Gold
50mm F1.2 VRL (Prototype)
50mm F1.4
50mm F4 Macro
55mm F1.8
55mm F2
85mm F1.8
85mm F2.2 Soft
100mm F4 Bellows
100mm F4 Macro
105mm F2.8
120mm F2.8
135mm F2.5 (1975 SMC PENTAX 1:2.5/135)
135mm F2.5 (1977 SMC PENTAX 1:2.5 135mm)
135mm F3.5 (1977)
150mm F4
200mm F2.5
200mm F4
300mm F4
300mm F2 (Prototype)
400mm F5.6
500mm F4.5
1000mm F8
1000mm F11 Reflex
2000mm F13.5 Reflex

ZOOM 28-50mm F3.5-4.5
ZOOM 45-125mm F4
ZOOM 80-200mm F4.5
ZOOM 85-210mm F3.5
ZOOM 85-210mm F4.5
ZOOM 135-600mm F6.7
ZOOM 400-600mm F8-12 Reflex


Asahi Pentax-M Series
M 20mm F1.4 AL (Prototype) - appears to have been previously miscategorised
M 20mm F4
M 28mm F2
M 28mm F2.8 ver I
M 28mm F2.8 ver 2 lacks silver ring
M 28mm F3.5
M 35mm F1.4
M 35mm F2
M 35mm F2.8
M 40mm F2.8
M 50mm F1.4
M 50mm F1.7
M 50mm F2
M 50mm F4 Macro
M 85mm F2
M 100mm F2.8
M 100mm F4 Macro
M 120mm F2.8
M 135mm F3.5
M 150mm F3.5
M 200mm F4
M* 300mm F4
M 400mm F5.6
M 2000mm F13.5 Reflex

M ZOOM 24-35mm F3.5
M ZOOM 24-50mm F4
M ZOOM 28-50mm F3.5-4.5
M ZOOM 35-70mm F2.8-3.5
M ZOOM 40-80mm F2.8-4
M ZOOM 75-150mm F4
M ZOOM 80-200mm F4.5

Own up if you've got a complete set!

Yes they are, no electrical contacts until the A series.


Many folk believe the M of the M series stands for manual, which of course they are, but was really indicating the new 'miniature' range. This has led to some believing all K mount manual lenses are M series, which they are not. Many dealers and sellers don't understand this subtle difference, even if you point it out to them, hence many confusing adverts appear which are technically misdescribed..

K mount was the original fully manual lens series after the M42 was discontinued. normally designated 'SMC Pentax'
The M series were updated versions of these and other new introductions designed to be smaller (miniature) to go along with Pentax's new range of smaller SLRs staring with the ME and MX.

These are photos of both versions of the manual 20mm f/4 lenses for comparison:

SMC Pentax (K version):



SMC Pentax-M (M version):



These were followed by the A series with an auto diaphragm and then the F and FA series' both with auto focussing too. These led on to the D-FAs we now know and love(?)!

That 20mm f/1.4 falls in the first 'SMC Pentax' era rather than the later M version era.

Anyone got a spare 20mm f/1.4 and didn't know what it was?!

So how should one make a forum search to find references to the KP if the search function can't/won't cope?
I suppose that limits finding any reference to the K1 as well !
Suggest the search function limit is reduced to a two character minimum limit to enable searches for Pentax cameras or is it as Haris suggested PU doesn't want them disclosed!?

They look like satellite images of a distant planet!

What's gone wrong with it? Generally a PC crash does not cause a loss of data unless the hard drive has totally died.

They have of course, you just did! It's odd that a Pentax forum search ignores any model of Pentax camera though. It's what new users come here for. Maybe the search feature is currently broken.

Oddly, if you do a PU forum search for 'KP' (or kp) it doesn't find anything at all.

Does seem it could be
https://ricehigh.blogspot.com/2020/01/whats-inside-pentaprism-housing-of-new.htm...