[Ash]

it seems fa 20-35mm is a solid lens, distortion at 20mm being more or less the only issue

But there are others who say the FA 20 has more distortion than the 20-35. I cannot find an FA 20-35 MTF chart or photozone.de review of this lens to make an objective judgement on this. So what's the reality between the two lenses?

[Abbazz]

So let's say we're just looking at IQ at 20mm. At f/5.6-f/8, why does the 20-35 trump the 20?

Resolution wise, the FA 20 is better until F/5.6, especially in the corners. The FA 20-35 is no slouch either, but the corners are mushy wide open at F/4. They get better at F/5.6 and it's at F/8 - F/11 that sharpness gets optimal over the whole frame.

Surprisingly, distortion is a little bit better on the zoom and a little worse on the FA 20 (at least on crop format according to Photozone reviews here and here). Anyway, the distortion is normally not an issue with either lens on full frame, except when you have straight lines running near the edge of the frame.

Microcontrast and color rendering are a big advantage of the FA 20-35, which exhibits brilliant colors and constantly delivers punchy images. It has also a much greater resistance to flare when the sun is in the frame or just outside the frame.

Vignetting is present on both lenses when used wide open but becomes nearly invisible at normal landscape apertures of F/8-F/11.

Both lenses tend to suffer from lateral chromatic aberration (which is easily correctable) and from purple fringing on bright edges when used at faster apertures (this is more of a nuisance).

As a whole, I would say it's easy to pick the images from the FA 20-35 because they consistently look better when you see them next to the images from the FA 20. Technically, the FA 20 might be the sharper lens, especially when compared to the FA 20-35 at F/4, but at the apertures normally used for lanscape (F/8 - F/11), the FA 20-35 simply delivers better looking images.

Here's a quote from an old Shutterbug review of this lens:

From f/5.6 to f/16--the most commonly used apertures with wide angles--the zoom produced highly satisfying slides at every focal length, suitable for a fine 11x14 print or a double page magazine spread.

Cheers!

Abbazz

[EDIT] I just noticed the FA 20-35 is still listed on Ricoh-Pentax Japanese website: http://www.ricoh-imaging.co.jp/english/products/lens/k/wide/smcpentax-fa20-35/
It is still available new at their online store for ¥ 80,750 ($ 678) without taxes: http://store.ricoh-imaging.co.jp/g/gS0027960/

[hoopsontoast]

+1. It has quickly turned into my most used lens on full-frame, mainly because it's a light and compact zoom with a very useful range which delivers great pictures with lots of contrast and beautiful colors at any focal or aperture. There are certainly prime lenses that are sharper in the corners at F/4, but this tiny jewel trumps them all when it comes to packing a lot of punch in a small package.

There are so many beautiful pictures taken with this lens on this forum, like these, which were posted recently:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/287219-comp...ml#post3170061



IMHO the 20-35 is a more useful lens because it has better flare resistance and constantly delivers better colors, even though the FA 20 does have the lead in pure resolution until F/5.6. I have posted a few quick comparison shots taken on a full frame camera here:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/287925-ff-u...ml#post3169656

Cheers!

Abbazz

Nice comparisons, I think I shall stay with the FA20-35 after all

[Ash]

Well I give up - I will be getting both to do my own comparisons.
I just couldn't make up my mind which one I will find better for the upcoming FF camera.
And I won't be able to justify getting the new DFA UWA lens that will no doubt be announced around that time...

[johnha]

I couldn't decide between an FA20 or FA24 when I found an FA20-35/4, the versatility of the zoom won me over (and finding the FA20/FA24s was harder).

[Ash]

I was fortunate enough to find an FA 20 at KEH and there are several copies of FA* 24 on eBay from a Japanese vendor. I wanted as wide an angle as possible on FF and the 24mm just wasn't wide enough (especially when spoilt with the DA 12-24 on APS-C).

[tapiolan]

there were couple of new fa 20-35s on ebay from a german seller, with relatively reasonable price. I got one, now i need some better than awful weather to enjoy it.
I think I will stop looking for any new lens on the wide end, until maybe something comes up new for ff in 5 years.

[pinholecam]

I was fortunate enough to find an FA 20 at KEH and there are several copies of FA* 24 on eBay from a Japanese vendor. I wanted as wide an angle as possible on FF and the 24mm just wasn't wide enough (especially when spoilt with the DA 12-24 on APS-C).

The FA*24 did not turn out too well on the A7.
It seems a lens designed for closer focus distance work (eg. closeups, streets ) than distance 'infinity'.
Immediately off center, there is a noticeable drop in sharpness.
Perhaps by taking into account field curvature and focusing using the off center portion and f11, f16, it may get around this, but I did not try it. (sold mine, found it too big/heavy as a travel lens anyway and I don't need f2 on a 24mm)

So unless the Pentax FF is specially optimized with a thin sensor stack to cater for the old wides, the FA*24 may not perform too well on it for landscapes.

If its any consolation, I tried another fast 24mm, the more modern Sigma 24/1.8 and it had the same type of performance characteristic.

[Abbazz]

If its any consolation, I tried another fast 24mm, the more modern Sigma 24/1.8 and it had the same type of performance characteristic.

+1 regarding the Sigma EX wides. I have the 20/1.8 and the 24/1.8 and they are mediocre performers on full-frame -in fact the 20/1.8 is even worse than the 24/1.8! And these lenses are also huge beasts that take a lot of space in the bag. I like to travel light and there is no way that I will carry a 24mm lens that is much bigger than an 85/1.4...

Cheers!

Abbazz

[ogl]

FA20-35/4 has the one of the best 24 mm - better than FA*24/2. As for 20 mm - it seems to me FA20 is not better.

[angerdan]

But there are others who say the FA 20 has more distortion than the 20-35.
I cannot find an FA 20-35 MTF chart or photozone.de review of this lens to make an objective judgement on this.

Yea, FA 20mm has slight more distortion.
Pentax SMC-FA 20mm f/2.8 - Review / Test Report
Pentax SMC-FA 20-35mm f/4 AL - Review / Lab Test

photozone:
FA 20-35mm has 7,5% higher resolution in center than FA 20mm.
FA 20mm has 2,5% higher resolution in borders.

pentaxzone.free.fr:
http://pentaxzone.free.fr/03-25_Pentax-FA_20mm.html
http://pentaxzone.free.fr/03-12_Pentax-FA_20-35mm.html