[pinholecam]

I never really attached max aperture to a requirement with the Limited's. Lots of other things about them (they should be small, top build quality, 'pleasing' rending over clinically sharp at all apertures, etc). I hope that continues to be the case going forward.

+1
Limiteds are all round practical and very usable lenses (ie. size, robust build, versatile wide aperture but not overly so) yet at the same time jewels in the other aspects like all metal construction, refined construction and rendering focused on the image over just MTF numbers.

[Wheatfield]

I never really attached max aperture to a requirement with the Limited's. Lots of other things about them (they should be small, top build quality, 'pleasing' rending over clinically sharp at all apertures, etc). I hope that continues to be the case going forward.

You are implying that a high degree of sharpness and pleasing rendering are mutually exclusive. May I suggest that you visit the lens club thread devoted to the DFA*85/1.4, paying special attention to the work posted by Medex.

I just don’t think that a lens that isn’t really sharp wide open is one that will garner much acceptance in today’s market.

Digital imaging has moved that needle. In the film era we accepted that lenses had to be stopped down several stops to be sharp. I don’t see this as being the case any more, at least not for lenses that are being pimped as premium grade.

I expect we will get our Limited lens rendering, but I also think that the 21 will not be a sharpness slouch at whatever it’s maximum aperture turns out to be.

[JPT]

I never really attached max aperture to a requirement with the Limited's. Lots of other things about them (they should be small, top build quality, 'pleasing' rending over clinically sharp at all apertures, etc). I hope that continues to be the case going forward.

But interestingly, a max. aperture of f2 or faster was a design goal for the FA Limited series from the start. The first one was the 43mm and that focal length was decided specifically because they wanted to make a lens faster than f2 with a filter diameter of 49mm. Their simulations indicated that 43mm was the best choice to stay within those constraints.

It's already clear that they won't stick to those same constraints for the 21mm (we already know it's bigger and slower), but I don't think they will stray too far. Also, as Wheatfield says, technology and expectations have moved on, so what they can achieve now in wide open sharpness is probably a lot better.

One other thing that was clear from the presentation I saw about the Limited was that the consistency of rendering throughout the aperture range is something that they prioritize with star lenses, but not with Limited lenses. With the limited lenses they view the change in character when you stop down as something they want to retain. It makes it a less consistent but potentially more interesting instrument to use. Think about the 77mm. You have the wide open bokeh performance, the close focus ability at f2.4, the impressive sharpness at f5.6 and the starburst ability when stopped right down. So in a sense you are getting a lens capable of acting like several different lenses in one.

[Ishpuini]

43/1.9
77/1.8
31/1.8
15/4
21/3.2
35/2.8
40/2.8
70/2.4
Are all normal apertures.

I think we should disregard the DA limiteds as a guide to where the new 21mm would fit in terms of aperture, and only consider the FA limiteds since these are the only full frames ones. Also, from the size of the lens on the published images, it's clear that the new 21mm doesn't match with the DA limited priority of small size.

[Serkevan]

I think we should disregard the DA limiteds as a guide to where the new 21mm would fit in terms of aperture, and only consider the FA limiteds since these are the only full frames ones. Also, from the size of the lens on the published images, it's clear that the new 21mm doesn't match with the DA limited priority of small size.

I wouldn't be super sure we can consider the FA Limiteds either. They are from an era with other optical aberration tolerances - the 77 and 43 have a fair bit of fringing under many conditions. The DFA 21 might have some more correction built into its optical formula, but we'll see...

[deus ursus]

F1.8 is star not limited lens.

F1.9, then. :-)

[Ishpuini]

I wouldn't be super sure we can consider the FA Limiteds either. They are from an era with other optical aberration tolerances - the 77 and 43 have a fair bit of fringing under many conditions. The DFA 21 might have some more correction built into its optical formula, but we'll see...

True, I was referring to aperture and size only.

[pres589]

You are implying that a high degree of sharpness and pleasing rendering are mutually exclusive.

No I didn't. You extrapolated something I didn't suggest. Maybe I wasn't clear enough; the goal of pleasing rendering was higher on the priority list with the Limited lenses than critical sharpness wide open. Wide open sharpness does not seem to be completely off the table with the Limited glass! I only one one Ltd, the DA 15, but it performs well at its max aperture in my opinion. I think most all of them are like this lens. There's glass that is quite sharp and still renders nicely as you mentioned. But that glass is usually quite large by comparison. It's a series of tradeoffs.

[Zygonyx]

43/1.9
77/1.8
31/1.8

15/4
21/3.2
35/2.8
40/2.8
70/2.4
Are all normal apertures.

As for FA limited, the rule seems to be "clear" enough

[Wheatfield]

As for FA limited, the rule seems to be "clear" enough

A 21/1.8 would be nice, but the plebians will be wailing like they are having kittens when they see the price tag.

[TwoUptons]

I fall into the f:e camp... that would be fun...

I expect the lens to be sharp, with good transitions into out of focus areas and nice bokeh.

But it isn't a * lens, which to me means it isn't super-fast (which I think is consensus here), but also mean other corrections are done differently.

It may have some field curvature that would have been corrected out on a * lens.

I would be very satisfied with a lens with significant field curvature wide open (which might make for some really nice wide-angle portraiture and "soft" corners wide open) as long as it still rocks the landscapes at f5.6 or so...

I am a little worried it might have more coma than I'd like if I want to do some dark skies with it, but I guess we'll see...

-Eric

[Kunzite]

I am a little worried it might have more coma than I'd like if I want to do some dark skies with it, but I guess we'll see...

Yeah, it would be nice if coma would be well corrected...

[Ishpuini]

I am a little worried it might have more coma than I'd like if I want to do some dark skies with it, but I guess we'll see...

-Eric

If coma were kept under control the would make a very nice nightscape lens indeed!

[Rondec]

Fast and wide is really expensive -- at least if you have a good build and decent performance wide open. A lens like the FA 50 f1.4 or DA 50 f1.8 is cheap with a wide aperture, but both of those lenses have poor builds, aren't well corrected, aren't wide (50s are cheap to build) and really need to be stopped down at least to f2.8 to get border sharpness. It seems like Pentax has a different bar that they are aiming for here with this lens and as long as it has good wide open performance, it won't matter if it's max aperture is somewhere between f2 and f2.8.

[BarneyL]

Fast and wide is really expensive -- at least if you have a good build and decent performance wide open.

Sony FE 20mm 1.8 has good build, decent performance wide open and is cheaper than 31mm limited. It's also pretty compact for these kind of parameters, but I guess that mostly comes from short flange distance.