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06-17-2014, 04:20 PM   #886
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QuoteOriginally posted by ChristianRock Quote
The 18-35 was tested on a Canon sensor, which Lenstip says gives higher MTF numbers because the pixels are more densely packed. Not to mention, the Canon sensor is just a bit smaller, so that might make the corners just a little bit better than the Nikon/Pentax/Sony sized APS-C sensor.
So you can't just make a direct numeric comparison with the FA 31 unless it's on the same type sensor.
The Canon 50D has a 15.1mp sensor vs the K-5 with 16.3mp sensor so I don't think the 50D pixels are more densely packed. I just don't see how the 31mm F1.8 is worth $500 more than the 18-35mm F1.8 . You could get the 18-35mm F1.8 and HD Pentax-DA 55-300mm f/4-5.8 ED WR Lens for less than the 31mm F1.8 alone.

06-17-2014, 04:31 PM   #887
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QuoteOriginally posted by jogiba Quote
The Canon 50D has a 15.1mp sensor vs the K-5 with 16.3mp sensor so I don't think the 50D pixels are more densely packed. I just don't see how the 31mm F1.8 is worth $500 more than the 18-35mm F1.8 . You could get the 18-35mm F1.8 and HD Pentax-DA 55-300mm f/4-5.8 ED WR Lens for less than the 31mm F1.8 alone.
I have to agree. I have a 31, but if I didn't have it, and I were looking for something in that range, I'd go for the Sigma vs a 31, even a used 31. The FA 31Ltd is a great lens, just as the K20D was a great camera in its day, but time and technology march on.
06-17-2014, 04:44 PM   #888
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QuoteOriginally posted by jogiba Quote
The Canon 50D has a 15.1mp sensor vs the K-5 with 16.3mp sensor so I don't think the 50D pixels are more densely packed. I just don't see how the 31mm F1.8 is worth $500 more than the 18-35mm F1.8 . You could get the 18-35mm F1.8 and HD Pentax-DA 55-300mm f/4-5.8 ED WR Lens for less than the 31mm F1.8 alone.
Hm, the canon has 4.7. The Pentax has 4.8. Remember the canon has a smaller sensor.

I'll call it a tie.

The sigma is definitely a good deal. Some people don't want the weight and size. Personally I prefer the bokeh of the FA31, and I'm protecting against future full-frame, too.
06-19-2014, 11:17 AM   #889
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I just received this today. Hard to believe, it's been almost 1 yr to the day I placed my pre-order!

-------------

Good morning,



You are getting this e-mail because you have inquired about the 18-35mm for Sony and Pentax in the past. I am pleased to say that after many delays, these lenses are CONFIRMED for delivery new week. We are getting enough to fulfill all backorders we have in our system. So if you haven’t placed a backorder at a dealer or our website yet, please do so soon to ensure that you receive it before supplies run out.

Please let me know if you have any questions.



Have a great day!



Best regards,



M. S.

Sales Operations Supervisor

Sigma Corp of America

NEWsigmaLogotest


------------------

06-19-2014, 11:38 AM   #890
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The FA 31 limited versus Sigma comparison is one that is tough, because the FA 31 is a tiny lens in comparison and a lot more flare resistant. The 18-35 feels like it will be more for low light settings, but maybe not quite as good for use in landscapes.
06-19-2014, 11:38 AM   #891
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QuoteOriginally posted by leadfoot Quote
CONFIRMED for delivery new week.
Okay, just curious. Is this a typo on your part, or was that the actual wording?
"New week" could be any week. We have a new week every seven days.
06-19-2014, 11:56 AM   #892
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As soon as I am back home in the US I am placing my order. I think I will need to sell some of my lenses.
06-19-2014, 12:01 PM   #893
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QuoteOriginally posted by Parallax Quote
Okay, just curious. Is this a typo on your part, or was that the actual wording?
"New week" could be any week. We have a new week every seven days.
The email I received is what I posted, I only changed the SOS (Sales Operations Supervisor) name to initials. I noticed the typo as well.

I assume/hope delivery will be next week (week of June 23, 2014) to B&H, Adorama, etc.

06-19-2014, 12:25 PM   #894
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I had made my mind up to get the 18-35mm as soon as it was available, to use as a convenient, high quality, one-lens walk-around solution, but while I was waiting and waiting I ended up picking up a Sony RX100 II instead to serve the same purpose.

I love the RX100 II, but most of the few things that bother me are addressed in the new RX100 III, which is being released tomorrow. So with the 18-35mm and the RX100 III becoming available at almost exactly the same time, for almost the same price, I'm conflicted about which one I should buy. I'd like them both, but it's just not in the budget for now.
06-20-2014, 07:41 AM - 3 Likes   #895
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QuoteOriginally posted by Parallax Quote
I have to agree. I have a 31, but if I didn't have it, and I were looking for something in that range, I'd go for the Sigma vs a 31, even a used 31. The FA 31Ltd is a great lens, just as the K20D was a great camera in its day, but time and technology march on.
Well... honestly, I don't think the Sigma is a bit sharper because of "latest technology". Lens design has been around long enough that during the 90s, they could have made the 31 (or all Pentax lenses of that era) different if they wanted to. But that wasn't the philosophy of Hirakawa Jun, the lead Pentax designer at the time, who designed the FA 43 and 77 and I think oversaw the work that a couple other designers did on the 31, after his own 31 design wasn't considered competitive (supposedly he came up with a 31 f/2.4 based on the old K series design).

Forum member Greg from NorthCoastPhotographer.net made a summary of one of the points from Hirakawa's notes on the FA Limiteds design, that explains why they didn't go for "all out sharpness" and the "MTF Championship" as I call it...

"As an example of this new attitude toward lens design, I will explain how we dealt with field curvature and astigmatism correction. An ideal of current lens design is to make the subject plane as flat as possible. Through specific techniques [detailed in the original article], field curvature is reduced, leading to a lens that will produce excellent scores on numerical tests. However, flattening the subject plane comes at a cost: pictures taken with such a lens will lack spice. With the Limited lenses, small amounts of field curvature were left uncorrected so that we could remove “astigmatic difference.” While this reduces the overall numerical score of the lens, without the “astigmatic difference,” the point of focus can be depicted with a more tactile, three-dimensional rendering, leading to a better overall image."

"The Limited lenses weren’t merely corrected for various chromatic aberrations. Focus points for each color and out of focus boundaries were also aligned, allowing for a gentle transition from the object in focus to the out of focus portions of the image. The corrections applied to the Limited lenses are a bit different from those normally used in the design of lenses."


Source: Lessons from a Legendary Lens Designer | Photographic Ideals, Basic Principles | The Northcoast Photographer

So, if anyone goes with the Sigma, they should at least know they are going for a different design philosophy, not just to a more "technologically advanced" lens. I, in fact, believe that the coatings on the FA Limiteds are still better than any Sigma coatings - but that's just an impression, I have no way to prove it one way or another But that's probably where the technology advances more than other areas...
06-20-2014, 11:50 AM   #896
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QuoteOriginally posted by ChristianRock Quote
So, if anyone goes with the Sigma, they should at least know they are going for a different design philosophy, not just to a more "technologically advanced" lens.
Fascinating insight. Thanks! I'm not sure if such subjective and artistic design philosophies are given much weight these days; one gets the impression that the new Sigma "Art" lenses are designed to hit the best possible numbers. I may be wrong. But perhaps that is the inevitable result of high-resolution digital sensors and pixel peeping.

I will suspend judgement on the Sigma 18-35 until Pentaxians have carried it around for a few months. Is its size and weight just too much of a pain in the neck (back, shoulder, ...)?
06-20-2014, 12:12 PM   #897
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The only real "technology" that has changed has been manufacturing capability. Sure, new kinds of glass are available but the principles of optics have been well-established since Fresnel in the early 1800s. Physics has not changed.

Case in point: the Japanese during WWII were so radically far ahead in binoculars that they had no need of radar. With classical optics, they were able to do as well as the allies with their fancy modern radar machines. Think about that. And that was 70 years ago.

Pretty much anything can be made. That's not an issue. But making it affordable for consumers to purchase...that's the trick. The FA31 was designed for late 1990s manufacturing capability. The new Sigma is made for 2014 abilities. Precision and automation is much better now than it was 15 years ago. The FA lenses were also designed for film cameras, where chromatic aberrations are far less noticeable. At that time, correcting so stringently for CA was a waste of money; all it would do is make the lens more expensive for no gain for consumers. But now it matters.
06-20-2014, 12:22 PM   #898
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QuoteOriginally posted by MadMathMind Quote
Case in point: the Japanese during WWII were so radically far ahead in binoculars that they had no need of radar. With classical optics, they were able to do as well as the allies with their fancy modern radar machines.
Night vision binoculars in 1943???? That's pretty impressive.
06-20-2014, 12:41 PM   #899
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QuoteOriginally posted by Paul the Sunman Quote
Fascinating insight. Thanks! I'm not sure if such subjective and artistic design philosophies are given much weight these days; one gets the impression that the new Sigma "Art" lenses are designed to hit the best possible numbers. I may be wrong. But perhaps that is the inevitable result of high-resolution digital sensors and pixel peeping.
A lot of people just care about numbers nowadays... and those who don't, have a huge market of old lenses to choose from. It's hard to sell a new lens that doesn't cater to the "sharpness" crowd...

I do think these new Sigma lenses are made worrying mostly about sharpness numbers, but I'm sure they do take the rendering into consideration up to some point at least. But the bokeh tests that I've seen don't lie - it's not the "one lens to rule them all". It's one option, and a very good one at that. But if sharpness isn't your main concern, as a lot of people here claim, then it's your lens (as a side note - it's funny to see all these people worrying about sharpness across the frame, and when you look at what they use, it's zooms and even superzooms... but I digress...)

Back to the technological aspects...

QuoteOriginally posted by MadMathMind Quote
The only real "technology" that has changed has been manufacturing capability.
Well, to be totally fair, coatings did have changes recently, and that can be considered a technological gain. In the 90s there were the "ghostless" coatings, and then after that came the "nano" coatings. And I'm sure there's been other aspects that aren't as exciting to talk about.

Sharpness, however, has nothing to do with technology, except for the coatings part, which does come to play. Even more so in the aspect of "perceived sharpness" due to high contrast wide open. But most of the sharpness itself seems to be pure optics.

QuoteOriginally posted by MadMathMind Quote
Pretty much anything can be made. That's not an issue. But making it affordable for consumers to purchase...that's the trick. The FA31 was designed for late 1990s manufacturing capability. The new Sigma is made for 2014 abilities. Precision and automation is much better now than it was 15 years ago.
Some manufacturing processes don't change quite as much as we think they do.
And also, the manufacturing changed completely since these FA Limiteds were introduced - they used to be made in a factory in Japan, now they are assembled in Vietnam.
So my question is, are you just saying this because you are guessing, or do you have insights on how the manufacturing of optical lenses has changed, and more specific, what changes happened when Pentax moved its factory to Vietnam?

QuoteOriginally posted by MadMathMind Quote
The FA lenses were also designed for film cameras, where chromatic aberrations are far less noticeable. At that time, correcting so stringently for CA was a waste of money; all it would do is make the lens more expensive for no gain for consumers. But now it matters.
While I agree with you that this is the case, I don't agree it's a problem. Software gets rid of that with one click (well sometimes one click, plus a sliding bar... lol)
For example, my Tamron 70-300 which everybody thinks is a "purple fringe monster" (I see it called that a lot), has much less fringing than some of my manual prime lenses like the SMC-A 135mm f/2.8. And it's so easy to get rid of it, it doesn't bother me.
Now OOF fringing, however, is a different issue, but it doesn't seem to be a problem for these Pentax lenses designed since the 90s.
06-20-2014, 12:44 PM   #900
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CA has been very correctable for years.
PF has been correctable, kinda still in a PITA way, for the last couple of years.
OOF fringing? I've seen it in 'example pics', but never actually found it in a picture I was looking at.
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