[mikesbike]

The new lens seems to have real promise for being outstanding for FF use. Also very good for APS-C as well. As to that FF FOV on APS-C, even though f/4 instead of f/2.4, I love my amazingly small DA 15mm Ltd! It is so easy to have on hand in case it is needed!

As to that Samyang, if you really need f/1.8 and/or you cannot afford the new Pentax lens, it is a viable option. Otherwise, for me it would be the new Pentax Ltd hands down.

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Last edited by mikesbike; 10-30-2021 at 04:51 PM.

[stevebrot]

Pentax D-FA 21 f2.4 OR Samyang 20 f1.8 ?

Intended use? Use case(s) trump(s) price and brand.

I might add that there was a Pentax-A 20/2.8 on the marketplace recently.


Steve

[robbiec]

Specifications:

D-FA 21mm f2.4:
Weight = 416 g
Size = 74 x 89 mm
Filter size = 67mm
Autofocus = Yes
Pixie dust = Yes, in quantity
Takes square filters: No
Amazon DE price = 1511 Euro

Samyang 20mm f1.8:
Weight = 493 g (77 g heavier )
Size = 83x87 mm (+9mm diameter )
Filter size = 77mm
Autofocus = No
Pixie dust = Not included
Takes square filters: Yes
Amazon DE price = 483 Euro

Cost for Autofocus + Pixe dust ~1000 Euro ?

I don't understand the question. Only one of them is a Pentax DFA Limited. Surely, you can't conceivably consider... But you do don't ya

[biz-engineer]

My interest in a compact 20mm lens is to use it as a travel lens in combination with the DFA 28-105 for architecture shots. I know such kit works perfectly for me, because the DA 15ltd + Tamron 17-50 was my preferred and most used lens kit. When I bought the K1, the only modern wide angle lens for it was the DFA15-30 but I never take it for casual shooting because itself fills completely my shoulder bag, I can take any other lens or I need a larger bag or I need a second bag. Basically, carrying the 15-30 is like carrying the 70-200 2.8 or 150-450, it's for deliberate photography on location, not so much for travel. Problem is, I already have too many Pentax lenses (+ the smc M 50mm 1.7, that's 10 lenses in total). If I buy the DFA21, I can't sell the DFA15-30 because the DFA21 doesn't take square filters due to the non-detachable hood, while I have the 150mm filter system for the DFA15-30. So, I end-up with 11 lenses, + 1500 euros more into Pentax, ouch, that's a lot of money and one more step deeper into Pentax without knowing if Ricoh are going to keep up with camera tech. I'll not buy any other Pentax limited, it's just a wide / ultrawide companion lens to the small 28-105 for casual shooting, street, cityscapes.

---------- Post added 31-10-21 at 05:50 ----------

I might add that there was a Pentax-A 20/2.8 on the marketplace recently.

I found a couple of these on ebay, they are not particularly cheap. There are a number of FA 20 for sale on ebay Japan, not cheap either for used lenses, but less than $1500.

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Last edited by biz-engineer; 10-30-2021 at 09:26 PM.

[house]

Vintage uwas aren't good enough IMHO. A 50mm or short tele will do quite well. Uwa lenses will have a lot of flaws compared to contemporary glass. In addition they arent cheap like the longer focal lengths, nor are they plentiful.

[mikesbike]

Well, getting a prime within the same FL rarely obviates the need and use of a zoom lens. The prime adds additional use for certain needs that are important but does not replace the zoom lens. My DA 15mm does not in any way replace my Sigma 10-20mm f/3.5 lens. But, as I said, it is a wonderful high-quality effortless carrying tool added to expand most any other kit.

The new FF 21mm f/2.4 would relate in much the same way for use with your K-1 kit. Though more costly, and not small- but that is something we have to accept when going with FF, the Samyang is bigger yet, and the new Pentax lens is far more refined in many ways.

[stevebrot]

I found a couple of these on ebay, they are not particularly cheap. There are a number of FA 20 for sale on ebay Japan, not cheap either for used lenses, but less than $1500.

Sadly, both the A 20/2.8 and FA 20/2.8 are definitely not cheap, but the prices reflect both availability (were expensive niche products when new) and reputation. I badly wanted either as a 28mm equivalent when I first got my K10D, but could never quite justify the price. I would expect they would outperform the Samyang, but without the f/1.8 maximum aperture.


Steve

[house]

I would expect they would outperform the Samyang, but without the f/1.8 maximum aperture.


Steve

I'm pretty sure they Samyangs outperform all vintage pentax 20 with some margin.

Really some margin. The dfa21 may well be a close call.

Most Samyangs are very good optically. The 135 ouperforms the Zeiss in many ways.

[stevebrot]

I'm pretty sure they Samyangs outperform all vintage pentax 20 with some margin....

I am pretty sure that I don't know. I don't own the Samyang 20/1.8 or either of the Pentax 20/2.8s. How about you? Do you own any of the three?

If not, perhaps you may be interested in the Lonely Speck review of the Samyang 20/1.8 where they found sufficient coma and vignette wide open to suggest shooting at f/2.8 and narrower?

Rokinon 20mm f/1.8 Astrophotography Review: Joshua Tree National Park – Lonely Speck


I like my two Samyangs (3mm fisheye (APS-C only) and 14/2.8 (covers 24x36mm FF)) and both are quite up to my standards, optically. In fact, I am very fond of both. That said, I have reservations regarding Samyangs out-the-door quality. Neither lens was properly dialed in for infinity focus and my first copy of the 14/2.8 was badly de-centered as well. From that perspective, I found a very recent Samyang 20/1.8 review here on PF that might temper my enthusiasm for that lens, were I in the market.

Samyang 20mm F1.8 ED AS UMC Lens Reviews - Samyang Lenses - Pentax Lens Review Database

The cool part is that they eventually got amazing results on the K-1 from a hand-picked copy and rated it a "10".

Bottom line is while I am a huge fan of Samyang, I might pass on the 20/1.8 if offered a v.good to ex- Pentax-A 20/2.8 for $350, knowing that I could easily sell it for that should it not meet expectations.


Steve

[biz-engineer]

Well, getting a prime within the same FL rarely obviates the need and use of a zoom lens.

I get that in general. Specifically with wide / ultra-wide lenses, my experience says something different: I don't need a zoom around UWA because I found my optimal wide angle focal length I like to work with and I found that little movements are enough to change compositions / perspectives when using a wide angle prime. I use the DFA15-30 mostly at 20mm and never at 30mm unless I don't have any other lens with me, otherwise I use another lens; I almost never use the DFA15-30 at 15mm, too wide to my taste. The only reason I bought the 15-30 at the time was 1) there was no other wide angle choice new for the K1 and 2) the discount from buying a camera+lenses bundle. I've use the DA15 and DA17-70 kit a lot, it's my ideal travel kit: 1 wide prime and 1 trans-standard zoom. For the K1, my ideal compact kit would be: 20mm prime + DFA 28-105, and with that kit only I can do a lot.

[angerdan]

I'm pretty sure they Samyangs outperform all vintage pentax 20 with some margin.

How do you define vintage?
And how do you separate legacy from vintage?

[biz-engineer]

How do you define vintage?

Vintage = from the era when men wore elephant trousers, you had neither internet nor cell phones you telephone line and TV set were both analog, the Woodstock hippies, when people could smoke in bars and didn't use condoms (except to avoid unwanted pregnancies) , and car parks were covered with oil puddles

[Parallax]

Specifications:

D-FA 21mm f2.4:
Weight = 416 g
Size = 74 x 89 mm
Filter size = 67mm
Autofocus = Yes
Pixie dust = Yes, in quantity
Takes square filters: No
Amazon DE price = 1511 Euro

Samyang 20mm f1.8:
Weight = 493 g (77 g heavier )
Size = 83x87 mm (+9mm diameter )
Filter size = 77mm
Autofocus = No
Pixie dust = Not included
Takes square filters: Yes
Amazon DE price = 483 Euro

Cost for Autofocus + Pixe dust ~1000 Euro ?

Beef hot dogs $3.97 per pound
T-bone steak $14.47 per pound.
Walmart price.

Cost for a bone $10.50

[house]

How do you define vintage?
And how do you separate legacy from vintage?

I don't!

All Pentax 20mm primes are vintage. 1995 (FA20mm launch) is 26 years ago and the lens is not in production. Samyang may well have QA issues but their 20mm is 21 years younger with a much more complex optical design and a performance that isn't that far off the DFA21 as can be seen in the recent comparisons at pentaxian.de

The FA20 is also a tiny lens. Pentax may be good but they aren't magicians.

I don't own either lens but the following seems about right after comparing samples. I have looking at PK wide angle primes since I got my K-1. I do own the Samyang 1.4/24 which is optically excellent but I still dislike it.

Rokinon 20mm f/1.8 Astrophotography Review: Joshua Tree National Park – Lonely Speck

Overall, the performance of the Rokinon 20mm f/1.8 very good for the price. Yes, it’s not perfect at f/1.8 but it’s really not that bad either. Having the option to use f/1.8 when noise is a concern is invaluable and the fact that the aberrations almost completely clear up at f/2.8 means that it can offer similar performance to one of my favorite lenses in the 18-20mm range currently: the Zeiss Batis 18mm f/2.8. Did I mention the Batis costs almost a thousand more? Sure the Rokinon has no autofocus, no depth of field scale, is larger and heaver. But optically, it’s pretty good, especially when stopped to f/2.8

They are just from completely different era's



Adding the ancient Pentax 20mm's for comparison. Makes it obvious how similar to the really old designs the FA is



and the DFA21

[angerdan]

I don't!
All Pentax 20mm primes are vintage.

I do separate between historic, vintage, film era, legacy, current and modern lenses, which classifies the FA 20mm as legacy:

How about this definitions?

• Vintage..= Manual focus lenses out of production since AF era (Oldtimer)
  K, M, A lenses
• Film Era.= Lenses which had been developed during AF era but before the first compatible DSLR camera was available. Should have an aperture ring.
  K, M, A, F, FA lenses
• Legacy...= AF or at least MF lenses with electronical contacts. Out of production, only available used. Should have an aperture ring. (Youngtimer)
  F, FA, D FA lenses (discontinued DA lenses too?)
• Current..= everything available new (booth AF and MF, first party and third party manufacturers)
  D FA, DA
• Modern..= offers at least two advanced technologies (★, new optical formula, newest lens coating, recent AF motor technology, electronical aperture control, weather sealing)
  D FA, DA

This definition has been developed and published without critics in:
Who Needs Modern Lenses? - Page 2 - PentaxForums.com