[zapp]

The new 21 Ltd fills a gap in the portfolio. That does not mean that everyone needs this lens. It will offer a certain feature set beyond the FA20 and will cost more as well. The whole strategy is in line with Pentax presentation of FF lenses recently. High quality glass, at reasonable price, modern design.

[mlt]

To me the HD Pentax-D FA 21mm ED Limited DC WR being longer than the smc Pentax-FA 31mm f/1.8 AF ED Limited speaks first and foremost of a much shorter focal length, less than half the back focal distance, hence a retrofocus / inverted telephoto design with a front group of much higher negative power, hence:

1. an optical centre farther from the front group, hence a longer lens and
2. much more pronounced aberrations to be corrected (distortion, coma, lateral chromatic aberrations and more), hence more elements in both groups, the front negative group and the rear positive group, including more aspheric elements and/or more elements made of special glass, hence a more expensive lens

all other things being equal.

Add higher image quality requirements (lesser drop in sharpness outside the centre, aberrations better corrected) on top of the constraints arising from the shorter focal length and you'll obtain an even bigger and more expensive lens.

Great explanation, thank you Mistral75.

[thibs]

The new 21 Ltd fills a gap in the portfolio. That does not mean that everyone needs this lens. It will offer a certain feature set beyond the FA20 and will cost more as well. The whole strategy is in line with Pentax presentation of FF lenses recently. High quality glass, at reasonable price, modern design.

Yes but wasn't the FA*20 a bit so-so on K-1 or was it the FA*24 ?

[angerdan]

Yes but wasn't the FA*20 a bit so-so on K-1 or was it the FA*24 ?

There's no FA* 20, only FA* 24.
The FA 20mm f2.8 is sharp at the center, but get's weaker outside and poor on the corners (on the K-1).

The FA* 24mm f2.0 delivers higher resolution outside and on the corners.
SMC Pentax-FA* 24mm F2 AL [IF] Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database

[reh321]

To me the HD Pentax-D FA 21mm ED Limited DC WR being longer than the smc Pentax-FA 31mm f/1.8 AF ED Limited speaks first and foremost of a much shorter focal length, less than half the back focal distance, hence a retrofocus / inverted telephoto design with a front group of much higher negative power, hence:

1. an optical centre farther from the front group, hence a longer lens and
2. much more pronounced aberrations to be corrected (distortion, coma, lateral chromatic aberrations and more), hence more elements in both groups, the front negative group and the rear positive group, including more aspheric elements and/or more elements made of special glass, hence a more expensive lens

all other things being equal.

Great explanation, thank you Mistral75.

Yes, my understanding is that the "natural" focal length of a lens is the same as its flange distance.

Since both the M42 and K mounts have a flange length of 45.5mm, the lens will naturally get longer as it gets farther from that distance,
which is why my Takumar 35mm lens {on left} is longer than my Takumar 50mm lens {on right} - and 21mm is even farther from 45.5mm.
There are design 'tricks' that can be used to reduce the length of a lens, but using them adds to the cost of a lens, so this length may be another argument for a lower cost.

[angerdan]

Official (preproduction) product photo from Pentax:

Source:
ricoh-imaging.eu/de_de/blog/pentax/neue-pentax-produkte-in-vorbereitung/

[Mistral75]

Official (preproduction) product photo from Pentax:

Source:
ricoh-imaging.eu/de_de/blog/pentax/neue-pentax-produkte-in-vorbereitung/

There are even two of them.

[pres589]

.... how are they still not telling us the max aperture of this lens?

[reh321]

.... how are they still not telling us the max aperture of this lens?

Are you asking about its widest opening or its smallest opening?

[pres589]

Widest opening. Max aperture. Min aperture will be either f16 or f22 and I'm not too bothered either way.

[Serkevan]

.... how are they still not telling us the max aperture of this lens?

They haven't said anything since May, I think... so not surprising. I guess we'll know something else the next time they give an update on the other things in development (21 Limited, 16-50/2.8 PLM so far).

[starjedi]

They haven't said anything since May, I think... so not surprising. I guess we'll know something else the next time they give an update on the other things in development (21 Limited, 16-50/2.8 PLM so far).

Hopefully it is FA 21 Limit F2.1.

[pres589]

They haven't said anything since May, I think... so not surprising. I guess we'll know something else the next time they give an update on the other things in development (21 Limited, 16-50/2.8 PLM so far).

That's seven (7!) months ago and they're now showing more complete images of the thing in both silver and black. What's not surprising about knowing the max aperture at the same time or before these images of the lens are being shared by Ricoh themselves?


I'm not really in the market for this thing anyway so it's not a big deal to me really. Just kind of odd how slow this rollout seems to be. Tell me about a 26mm fast prime instead and I'll become more annoying about it.

---------- Post added 12-12-20 at 09:48 PM ----------

Hopefully it is FA 21 Limit F2.1.

Not a chance. It would be twice as large OR not very optically good. Or both. The fastest I can imagine this thing being is f2.4 and f2.8 wouldn't shock me. f2.8 seems more likely than anything to me honestly.

[Serkevan]

That's seven (7!) months ago and they're now showing more complete images of the thing in both silver and black. What's not surprising about knowing the max aperture at the same time or before these images of the lens are being shared by Ricoh themselves?

They aren't showing "more complete images". The images are from May, nothing new there . The link is to the article on the German website about the video in question... published on May 15.

[Sandy Hancock]

Silver please.
Just take my money.