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11-04-2014, 09:47 AM - 2 Likes   #16
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As an optical designer, I can provide my two canadian cents.

QuoteOriginally posted by cxdoo Quote
1. Optical formula

This is what we see when patents are filed (and most of us don't understand it at all, apart from counting the elements/groups). But then, patents expire.
So what is there to stop company X from digging through old patents and copying successful/unique/whatever old glass for fun and profit? Is there somebody already doing this? Samyang maybe? These are all honest questions and I'd like if someone could chip in with some answers.
What you write is true, in theory. In practice, a number of things influence this.

First, patents are not always complete and accurate. So the patent is often not enough to manufacture a lens. In addition, patents are often too generic. You should know that, most of the time, when designing a lens the actual process starts from a lens catalog of existing designs (1000$ will buy you about 10k designs that can be loaded in optical design programs). You then adapt the basic design to fit your needs and requirements, and that fine tuning makes or breaks the design.

Second, manufacturing capabilities will be different from one company to the other, so it's not possible to build every theoretical design in the world. Each company will have its in-house know-how and wizards.

third, each designer has his tricks, each company its preferences. A designer might prefer to optimize MTF (a measure of sharpness), another colour flatness, another will work to keep performances uniform across the field of view, or lower aberrations, etc.

QuoteOriginally posted by cxdoo Quote
2. Glass

Apart form the exception below, I believe all players in retail market are capable of producing glass of similar quality at similar price points. If that's not the case, I'd like to hear more about it.
Actually lens manufacturers don't make their own glass, they purchase it from the likes of Corning, Schott, Hoya and a few others.

QuoteOriginally posted by cxdoo Quote
3. Coatings

This is supposedly Pentax's strength. But within Pentax lenses, why would a lens be unique due to coating?
Coatings are an intrinsic part of a lens's design.

What a coating does is change the transmission and reflection properties of the glass. Without coatings, every optical surface will reflect roughly 4% of the incoming light. That's true for windows, mirrors, and lenses. And that's true for EVERY surface. So the most basic lens element, a doublet (two materials glued together with convex surfaces) will have 3 surfaces:



That's 4% for each of those surfaces, plus 4% of the reflections themselves.

Coatings help you there. They reduce dramatically the amplitude of the reflections, and can help flatten the spectral response too (the way each colour is affected, transmitted, absorbed, reflected by the glass).

Coatings will affect light transmission, colour, flare, halos, contrast.

Each company has its tricks again, even though the basics are all the same. There are thousands of ways of making coatings, they will be affected by angle of incidence, the glass they are applied on, and so forth.

I hope this helped.

11-05-2014, 02:08 AM   #17
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QuoteOriginally posted by savoche Quote
For some insights on lens coatings and other design matters I think this interview is worth the time watching. Thanks to @dosdan for finding the clip.

Interview with a Zeiss master

Thanks for sharing (& thanks to dosdan too!). I found it interesting and worth the time, however the title is slightly misleading; Zeiss guy doesn't (didn't?) work in lens design but in testing so the perspective offered was slightly different from what I expected.

---------- Post added 5th Nov 2014 at 11:18 ----------

QuoteOriginally posted by bdery Quote
As an optical designer, I can provide my two canadian cents.
...


Thanks, that was very informative.
Thing about patents being incomplete is interesting, so if I infer correctly, they put in patent just enough information to be able to sue if someone manages to get something working out of it?
11-05-2014, 06:39 AM   #18
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QuoteOriginally posted by cxdoo Quote
Thing about patents being incomplete is interesting, so if I infer correctly, they put in patent just enough information to be able to sue if someone manages to get something working out of it?
That's a way to see it. A less cynical way would be to say that a patent does not require and often cannot include all the fine details. sometimes including too much information lets your competitors work around your patent too easily.

""A square? Let's make it a very very flat rectangle..."
11-05-2014, 06:46 AM   #19
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QuoteOriginally posted by bdery Quote
That's a way to see it. A less cynical way would be to say that a patent does not require and often cannot include all the fine details. sometimes including too much information lets your competitors work around your patent too easily.

""A square? Let's make it a very very flat rectangle..."


I'm glad optical industry shares the best practices of other industries. Speaking about rectangles, somebody should pull an Apple on patenting shapes and patent a lens as "transparent shape used to take photos".

11-05-2014, 07:05 AM - 1 Like   #20
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My thoughts on the 77... cross posted from the thread, linked below.

Just because 77 is a magical number and it's the pinnacle of Hirakawa Jun's design tenure at Pentax....
And the patent for the lens uses the famous pre-Hoya Pentax philosophy, "designed for the way people take pictures, not to do well on the numerical tests"
Given the current focus on numerically perfect designs, we may never see a design with the qualities of the 77 again. I'm not sure anyone but Jun even knew how to design a lens like this. And look at the maximum apertures, almost all except the fisheye ƒ2.8 or wider. When you see Pentax's current offerings, how obvious is it he's no longer there?

Lenses by Jun

DA 10-17mm Fish-Eye
DA 14mm f2.8
FA ★ 24mm F2.0 AL
FA 28mm F2. 8AL
FA 35mm F2
DA 40mm F2.8 Limited
FA 43mm F1.9 Limited
DA ★ 55mm F1.4 SDM
FA 77mm F1.8 Limited
FA ★ 80-200 F2.8
FA ★ 85mm F1.4 (IF)

That would be an awesome set of lenses. I have the DA 10-17, which is an awesome lens I don't use enough. It's a fun lens.
There are some fine lenses on that list for sure. If you jut went for a Hirakawa collection you'd have a fine set of lenses. Although, it looks like he never designed a macro.

Hirakawa Jun - Camerapedia


Read more at: https://www.pentaxforums.com/forums/40-homepage-official-pentax-news/277751-f...#ixzz3ICcuzkGH

So I'm going to say, I don't know what a great lens is, but the 31 ltd. which I believe was a co-peration with Zeiss, and all of Hirasawa's designs seem to have a certain reputation amongst users, while those who haven't used them complain about imagined technical limitations..

I don't know, but I think Hirakawa Jun did.
I don't need to know why I like it, I just need to know what to look for when I want one.
11-05-2014, 03:04 PM   #21
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Thx for your thoughts, Norm.

Thing about 'uniqueness' and other unquantifiable stuff is that you need a reference point. A rational person shouldn't really fall for talk about 'specialness', but follow hard numbers, and that means getting high scoring lens(es) first. Only then it makes sense to explore further, and individually judge how much nominal sharpness (and other measurables) you are happy to lose for that special something nominally inferior lens provides. However, the problem there is that, for most, once they reach 'good enough' they lose the incentive to experiment further. Particularly if that means shelling out significant amounts on a promise of magic. I fell for that with FA43. I'll probably do it for FA77. FA31... not so sure.

But before all that, I went for Tamrons. High scoring, relatively low priced, pedestrian lenses. And I'd do it again if I was in the same spot. I'd also recommend to anyone to do so.
So in a way, no wonder Pentax moved away from 'specialness'; it's a hard sell to masses and, in a sense, it requires an acquired taste (and spare cash).
11-05-2014, 05:00 PM   #22
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QuoteOriginally posted by cxdoo Quote
So in a way, no wonder Pentax moved away from 'specialness'; it's a hard sell to masses and, in a sense, it requires an acquired taste (and spare cash).

Bless.


There's no value in trying to emulate Canon and Nikon in mass production and low margin when you're the distant third or fourth player in a declining DSLR market.


You want the body and lens designs to be slightly unconventional.


Hirakawa and other Pentax designers understood that.


21, 43, 77mm - what weird focal lengths by Canikon standards!

Last edited by clackers; 11-05-2014 at 05:12 PM.
11-06-2014, 05:47 AM   #23
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QuoteOriginally posted by cxdoo Quote
I checked Bojidar Dimitrov's great page to see what lenses FA43 is related too. From what I see, there are several fifties with same number of elements.

K/A 50/1.2



K/M 50/1.4



and

A/F/FA 50/1.4




Of those, FA43 looks most similar to the last one to me.

FA43/1.9



Now it would be nice if someone who has one of the A/F/FA 50/1.4 and FA43/1.9 shared their opinion on similarities and differences between these lenses.
I use FA50 1.4 and FA43 1.9.

Similarities: Pentax-type colours and contrast.

Differences: FA43's colours are more striking/stronger. Contrast is stronger. Micro-contrast is more evident, and extremely finely graduated. Images have a 3D-effect. Bokeh character is different. Overall a more vivid, intense, characterful result.

---------- Post added 11-06-14 at 09:54 PM ----------

QuoteOriginally posted by clackers Quote
Bless.


There's no value in trying to emulate Canon and Nikon in mass production and low margin when you're the distant third or fourth player in a declining DSLR market.


You want the body and lens designs to be slightly unconventional.


Hirakawa and other Pentax designers understood that.


21, 43, 77mm - what weird focal lengths by Canikon standards!
Here's how 43mm is derived.

Taking a rectangle of 36mm x 24mm (is full range), measure the diagonal. It is 43mm.


Last edited by KDAFA; 11-06-2014 at 06:04 AM.
11-06-2014, 06:22 AM   #24
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QuoteOriginally posted by KDAFA Quote

Taking a rectangle of 36mm x 24mm (is full range), measure the diagonal. It is 43mm.

Yeah, you could argue it's as normal as normal could be on FF, but Canikon owners may still shake their heads hearing about it.
11-06-2014, 07:11 AM   #25
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QuoteOriginally posted by clackers Quote
Yeah, you could argue it's as normal as normal could be on FF, but Canikon owners may still shake their heads hearing about it.
Doesn't matter, really.
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