SMC Pentax 20mm 1.4

**dkpentax** · 05-09-2022, 05:53 PM - **25 Likes**

So here is what I've learned about the lens and some pictures.

For the Lens database:
Regular K-mount with the newer M-style font and lens speed format. Since it doesn't say "Pentax-M", I would list it as a K-mount prime.
Weight is 465 grams
Diaphragm is 8 blades
Front lens cap is a 77mm, same as the k-mount 300mm and 400mm lenses.
Minimum focus is .8 ft / .25m

Compared to the brand new 21mm Limited lens, the 20mm is a little shorter but is also lacking the 21mm's built in lens hood.

As you can see in the pictures the speed of the lens comes from one oversized front element, the rest of the lens is a normal size. Also you can see that unlike most of the old wide angle lenses Pentax made from this time period, the 20mm lens has a full size rear element.

I will post some image tests in another post.

Attached Images

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**mikesbike** · 05-09-2022, 06:55 PM

Very interesting. I knew of the M 20mm f/4 MF lens, but not one of f/1.4 which is a remarkable achievement in a FF lens this compact. It makes one wonder how well it performs wide open or close to it.

**kiwi_jono** · 05-09-2022, 08:37 PM

Wow, thats interesting. Never heard of that one.
Look forward to seeing the tests!

**iheiramo** · 05-09-2022, 09:04 PM

So it is in the hands of a member. Superb! Very interested to see the shots it can produce and how it compares to new 21ltd. Rendering most likely won't be flawless as it didn't get into production.

Sandy Hancock · 05-09-2022, 10:29 PM - **7 Likes**

You outbid me, you bastard

But seriously, congratulations on acquiring a true unicorn of the photographic world. I can't wait to see some sample images.

Adam · 05-09-2022, 11:20 PM

What is the origin of the lens itself- it is a prototype that ultimately went on to go up for auction?

pschlute · 05-10-2022, 12:08 AM

A true rarity. Thanks for posting.

pid · 05-10-2022, 12:33 AM

wow! Never saw one, always wanted it and never had the chance to get one. Congratulation. How much was it and where did you find it?

Saw it my first time on this site: http://kmp.pentaxians.eu/lenses/_prototype/k20f1-4/
May be you want to support them with the missing Infos:

K 20/1.4 AL

Product Information
Exact Name: SMC PENTAX 1:1.4 20mm
Color: black
Year of Introduction: 1976

Technical Specifications
OpticsOptical Formula: 11 elements in 10 groups
Aperture Range: f/1.4 ~ f/22
Number of Aperture Blades: unknown
Minimum Focusing Distance: 0.25 m
Maximum Magnification: unknown
Special Features: aspherical element(s)

Mechanics
Filter Diamete: r77 mm
Maximum Diameter: 80 mm
Length: 65 mm
Weight: 445 g

Accessories
Cap: unknown
Fitting Hood(s): unknown
Fitting Case(s): unknown

**S.M.** · 05-10-2022, 01:01 AM

Interesting, I would like to see some photos take with that lens.

LennyBloke · 05-10-2022, 01:42 AM

Thank you for sharing the images and information - it'll be great to see some images taken with the lens when you get a chance

shyrsio · 05-10-2022, 02:58 AM

Oh wow, you really did catch a unicorn!
Cant wait to see some samples taken with it.
I guess this gives us hopes of seeing the 35mm/1.4 in the wild too.

Jonathan Mac · 05-10-2022, 03:35 AM

For those who didn't see it, this thread tells the story of this lens since it first popped up on the forum radar in May 2019: SMC Pentax K 20mm f/1.4? - PentaxForums.com

I'm very glad it was bought by a forum member. Can't wait to see some sample shots with it.

**Joetitch** · 05-10-2022, 03:35 AM

I just don't understand how you ended up in possession of my lense?????
Super green with envy.😁

Sandy Hancock · 05-10-2022, 03:45 AM

Originally posted by Adam

What is the origin of the lens itself- it is a prototype that ultimately went on to go up for auction?

My understanding is that something like seven prototypes were made, and that's it.
The K 20/1.4 never made it to sale. Of course

**Digitalis** · 05-10-2022, 08:06 AM - **1 Like**

Interesting, the rear element looks almost exactly like the one found on the SMCP-K 50mm f/1.2

05-09-2022, 11:20 PM	#6
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	What is the origin of the lens itself- it is a prototype that ultimately went on to go up for auction? Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

05-10-2022, 12:33 AM	#8
pid Pentaxian Join Date: Jan 2010 Photos: Gallery Posts: 567	wow! Never saw one, always wanted it and never had the chance to get one. Congratulation. How much was it and where did you find it? Saw it my first time on this site: http://kmp.pentaxians.eu/lenses/_prototype/k20f1-4/ May be you want to support them with the missing Infos: K 20/1.4 AL Product Information Exact Name: SMC PENTAX 1:1.4 20mm Color: black Year of Introduction: 1976 Technical Specifications OpticsOptical Formula: 11 elements in 10 groups Aperture Range: f/1.4 ~ f/22 Number of Aperture Blades: unknown Minimum Focusing Distance: 0.25 m Maximum Magnification: unknown Special Features: aspherical element(s) Mechanics Filter Diamete: r77 mm Maximum Diameter: 80 mm Length: 65 mm Weight: 445 g Accessories Cap: unknown Fitting Hood(s): unknown Fitting Case(s): unknown Last edited by pid; 05-10-2022 at 12:45 AM.

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05-09-2022, 06:55 PM	#2
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,549	Very interesting. I knew of the M 20mm f/4 MF lens, but not one of f/1.4 which is a remarkable achievement in a FF lens this compact. It makes one wonder how well it performs wide open or close to it.

05-09-2022, 08:37 PM	#3
kiwi_jono Loyal Site Supporter Join Date: Dec 2009 Location: Christchurch, New Zealand Photos: Gallery \| Albums Posts: 2,437	Wow, thats interesting. Never heard of that one. Look forward to seeing the tests!

05-09-2022, 09:04 PM	#4
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	So it is in the hands of a member. Superb! Very interested to see the shots it can produce and how it compares to new 21ltd. Rendering most likely won't be flawless as it didn't get into production.

05-09-2022, 10:29 PM - 7 Likes	#5
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,272	You outbid me, you bastard But seriously, congratulations on acquiring a true unicorn of the photographic world. I can't wait to see some sample images.

05-10-2022, 12:08 AM	#7
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,202	A true rarity. Thanks for posting.

05-10-2022, 01:01 AM	#9
S.M. Site Supporter Join Date: Mar 2019 Location: Merano (BZ) Photos: Gallery \| Albums Posts: 108	Interesting, I would like to see some photos take with that lens.

05-10-2022, 01:42 AM	#10
LennyBloke Pentaxian Join Date: Aug 2008 Location: Worcestershire, UK Photos: Gallery Posts: 677	Thank you for sharing the images and information - it'll be great to see some images taken with the lens when you get a chance

05-10-2022, 02:58 AM	#11
shyrsio Pentaxian Join Date: Apr 2016 Location: Tirana Posts: 780	Oh wow, you really did catch a unicorn! Cant wait to see some samples taken with it. I guess this gives us hopes of seeing the 35mm/1.4 in the wild too.

05-10-2022, 03:35 AM	#12
Jonathan Mac Pentaxian Join Date: Apr 2009 Location: Madrid, Spain Posts: 10,897	For those who didn't see it, this thread tells the story of this lens since it first popped up on the forum radar in May 2019: SMC Pentax K 20mm f/1.4? - PentaxForums.com I'm very glad it was bought by a forum member. Can't wait to see some sample shots with it.

05-10-2022, 03:35 AM	#13
Joetitch Site Supporter Join Date: Aug 2016 Location: Leura NSW Posts: 502	I just don't understand how you ended up in possession of my lense????? Super green with envy.😁

05-10-2022, 03:45 AM	#14
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,272	Originally posted by Adam What is the origin of the lens itself- it is a prototype that ultimately went on to go up for auction? My understanding is that something like seven prototypes were made, and that's it. The K 20/1.4 never made it to sale. Of course

05-10-2022, 08:06 AM - 1 Like	#15
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	Interesting, the rear element looks almost exactly like the one found on the SMCP-K 50mm f/1.2