[normhead]

Better lenses than Sigma... currently no one can easily match the performance of the Sigma Art series especially not at the price point. Different AF, weather sealing ... would differentiate a Pentax lens maybe, but if you define better by optical performance, it will be difficult to even match Sigam Art.
Questions is: would Pentax want their most expensive, most prestigious and most advanced lenses to come from Sigma? Would Sigma go for it. The idea of a Pentax branded weather sealed art series is very appealing, but I don't see it happen.

Sigma lenses over time all turn into paper weights. It happens when you can get something just as good with half the weight. MY Sigma 70 macro compared to the Tamron 90 macro, FA 50 macro and DFA 100 macro is a monster. All that weight for what? All those lenses are great lenses, and in that situation, sooner or later I'l end up with the lightest most efficient use of materials, and it's guaranteed, that won't be Sigma.

I had to come in last night shooting with my Sigma 70 macro, there was a light rain, beautiful light and awesome golden hour colour, but the lens was getting wet. Ya sure I could go in , get a plastic bag and futz around, or I could just watch "the Defenders" on Netflix and forget the whole thing. Of my 3 sigmas, one is broken, one is really heavy and not WR, and one I gave away because it was decnetered so bad even at ƒ8 you couldn't do a decent landscape with it. I am really not open to listening about how great Sigma lenses are, or even buying another one. I recommend them only to people who make it clear, their budget is going to force them to compromise. If you are willing to compromise maybe all that weight is an acceptable trade off for some. Personally I like as little compromise as possible and weight is a huge negative.

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Last edited by normhead; 08-20-2017 at 11:14 AM.

I'm not a blind fan that would believe in fairy tales about the high quality of DFA. DFA-24-70 \ 2.8 I had it !!! I sold it!!! This is a medium quality lens! I do not want any more Tamron! Sigma Art is excellent quality.

[Kunzite]

Why the aggressive language? "blind fan"? "fairy tales"?
The D FA 24-70 is made by Tamron, but here we're talking about high end Pentax lenses.

[ogl]

Thankfully it is easy to beat most Sigma Art lens in K-mountability

I doubt that Sigma Art will be in K-mount.

[normhead]

I'm not a blind fan that would believe in fairy tales about the high quality of DFA. DFA-24-70 \ 2.8 I had it !!! I sold it!!! This is a medium quality lens! I do not want any more Tamron! Sigma Art is excellent quality.

You need to look at Digitalis' comparison of the 31 ltd. and Sigma 30 1.4. Maybe pay a bit of attention to someone who actually has the where with all to evaluate lenses and do these kinds of comparisons.

I really don't see how being a blind fan of Sigma is any better than being blind fan of Pentax.

FA31 VS Sigma 30 1.4 Art - PentaxForums.com

31ltd vs sigma 30mm - PentaxForums.com

FA31mm F1.8. or Siggy 30mm F1.4 - PentaxForums.com

There's been lots of discussion, lots of folks who prefer one lens or the other. I'd suggest the biggest difference between the two lenses is weight. And the Sigma seems to have been able to make their lens cheaper by adding a lot of weight. That's great if you're looking at a framing hammer instead of a claw hammer but in photography weight serves no practical purpose, and folks , whatever the medium should expect to pay a premium for light weight practical gear over gear that's so heavy, you really don't want to use it. In canoeing I can buy a fibreglass pig for $1000 or an ultra-light easy to carry boat for $4000, so with other outdoor gear, people pay ridiculous prices for lightweight gear. I like my Sigma 70, but it rarely gets used as I have the FA 50 macro and Tamron 90 macro. It's great lens, but most of the time it's a shelf ornamaent.

So my moto remains, use sigma if you can't afford the Pentax and are young enough to handle the extra weight. On occasion I can afford the Pentax, and every year the weight becomes harder and harder to manage. So Sigma loses on both of the critical criteria.

Of my 3 Sigma lenses, I have nothing I want to keep, long term.

[ogl]

According to Photozone, the Sigma Art 20mm and 24mm are quite weak in the corners, unless stopped down.

DFA20/1.4 and DFA24/1.4 are strong in the corners? My bet is never be such lenses in K-mount.

This lenses are tested at 50 MP FF sensor and show really good performance.

For wide-angle lenses at 50 MP sensor conclusion of photozone is really good. Don't you think so?
24/1.4 ART
At f/2 the borders/corners are Okay and good to very good between f/2.8 and f/8. at 50 MP sensor!!!
barrel distortion (0.9%)

Don't forget that the center at 50 MP is already good level wide-opened.
24/1.4 is absolutely cool lens for FF camera and shows really excellent performance.

20/1.4 ART
The outer region improves drastically to good levels at f/2.8 and it even manages to achieve very good results between f/4-f/8

[normhead]

From
Sigma 24mm f/1.4 DG HSM | A ("Art") - Full Format Review / Lens Test - Analysis



Sigma 24 on APS-c


Pentax 18-135 at 24mm

Now there's what I like to see in a photozone graph of a lens. The curve of the DA 18-135, excellent or close to excellent all the way across the frame at, ƒ5.6 excellent both centre and edge and close to excellent on the extreme edge. Unless you are showing me a graph like that I'm not even interested in discussions of how "great" a lens tests at photozone. Maybe next time you mention photozone put up a couple of comparisons so we know what you're talking about, because my random selections make your point look bad. Maybe you could select some charts that make your lens look better. ( I usually do that before I open my mouth, it never hurts to actually know that the stats you quote mean what you think they mean.)

Attached Images

 

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Last edited by normhead; 08-20-2017 at 08:26 AM.

[Kunzite]

@ogl:
I surely hope the ultra-wide angle won't be an f/1.4 monster! The Sigma 20mm f/1.4 weights almost a kg (without being weathersealed!) and has a bulbous front element which prevents using filters.
Just in the line above there are 3 points where Pentax can do better: weight, build, filter usage. Despite the Sigma being an Art lens, thus somehow magical
Another is vignetting, 3.36EV on the Sigma (and near 3EV for the 24mm).
And another is coma, which is a bit of an issue on the Sigma.

Photozone's conclusion is that both lenses (and many others) are... just lenses. Target similar performance and cost criteria, and pretty much every major camera/lens company would be able to match it.
The 20mm is getting 4 stars @ 21MP (!). Even they are acknowledging it's not a perfect lens.

Oh, you "forgot" to quote this part from the 20mm review:
"Unsurprisingly things go downhill at the borders/corners. At f/1.4 and f/2 the results are very soft."
Or from the 24mm review:
"The outer image region is, unfortunately, soft at fully open aperture so there is clearly some room for improvement here."
Room for improvement. That can't be, with such a perfect lens

I'm talking exclusively about K-1 and lenses for FF ... the crop does not interest me

[thibs]

Sigma Art is the real optical high end now. In all aspects. It's hard to beat Arts in terms of resolution.
What will you say if Ricoh knock itself out?

On all aspects or on resolution?
Sorry it seems unprecise to me but could be me.

[normhead]

I'm talking exclusively about K-1 and lenses for FF ... the crop does not interest me

There is hardly any information of FF lenses on the K-1. SO what you seem to be saying is, because you can find information of lenses based on other systems, they are better. Unfortunately, every site out there warns you not to compare across systems, so what you are looking at is pretty much worthless except as general comparisons. Photozone hasn't tested even one lens on a K-1. Pay attention to the site warnings and ignore their findings for precise comparisons. There is nothing on that site saying any Sigma lens is better than any Pentax lens on a K-1. It's quite possible an old FA 24-90 is better than anything Sigma makes.

A bad lens is a bad lens regardless of format emptied on, butIf an FF lens isn't as good at 24mm on a crop sensor as a crop lens, how could it ever be rated a top quality lens on 35mm lens? A lens that's bad on APS-c is likely to test worse on FF. At least on APS-c you are only testing the strongest part of the lens.

[ogl]

@ogl:


Oh, you "forgot" to quote this part from the 20mm review:
"Unsurprisingly things go downhill at the borders/corners. At f/1.4 and f/2 the results are very soft."
Or from the 24mm review:
"The outer image region is, unfortunately, soft at fully open aperture so there is clearly some room for improvement here."
Room for improvement. That can't be, with such a perfect lens

You made me funny..
Your arguments are arguments of man who understand nothing in ultra wide angles lenses and the troubles in designing and manufacturing of such lenses. Sigmas are close to perfect for ultra wide lenses at 50 MP sensor. If you can't understand it, it's really problem.

The stars rating is just subjective opinion of Klaus and nothing else.

Did you ever make landscapes at 20 or 24 mm at f1.4-2 with FF? Maybe when you were film camera user?

[ogl]

On all aspects or on resolution?
Sorry it seems unprecise to me but could be me.

easy to check the reviews

not only resolution

[monochrome]

An old FA24~90 is surprisingly good on a K-1 from 28-70. Just as it was on its contemporary MZ-S.

[Kunzite]

You made me funny..
Your arguments are arguments of man who understand nothing in ultra wide angles lenses and the troubles in designing and manufacturing of such lenses. Sigmas are close to perfect for ultra wide lenses at 50 MP sensor. If you can't understand it, it's really problem.

The stars rating is just subjective opinion of Klaus and nothing else.

Did you ever make landscapes at 20 or 24 mm at f1.4-2 with FF? Maybe when you were film camera user?

I don't "make you funny" - whatever that means; but your attacks are laughable.
Please read my posts carefully and don't ignore relevant parts; as I just said:
"According to Photozone, the Sigma Art 20mm and 24mm are quite weak in the corners, unless stopped down. That is understandable, as making fast ultra wide-angle SLR lenses is not easy. However, it should also help us realize that Sigma Art lenses are neither perfect, nor magical - they're simply high-end lenses, which is precisely what Pentax is targeting with the new D FA* line."
I also said that I hope the Pentax ultra-wide is not a huge, heavy f/1.4 - so why are you asking me if I'm shooting landscapes at 20mm or 24mm at f/1.4-2? OTOH you were saying there will be no DFA20/1.4 and DFA24/1.4 - then ignoring the Sigmas' performance at those apertures.

I proved quite well that at least some Sigma Art lenses are not "close to perfect". While there are reasons for that, perfect means perfect and such weak corners, heavy vignetting etc. aren't "close to perfect".
It would be interesting to see Pentax tackling these challenges. But, I have every intention of buying... while you, from what I see, are interested in putting Pentax down.