Sigma 25 1.4 for m4/3

Started Jan 22, 2013 | Discussions thread
clengman Senior Member • Posts: 1,964
Re: Sigma 25 1.4 for m4/3

Ergo607 wrote:

clengman wrote:

Ergo607 wrote:

clengman wrote:

Ergo607 wrote:

clengman wrote:

I think the lead is getting buried here. It looks as though Sigma (not Leica) may have designed the optics for the pana-leica 25mm. Interesting, no?

Looking at both diagrams:

Sigma's patent

The diagram for the Leica 25 for m43 as found on four thirds org

then it looks like two completely different designs...

I'd like to get a fast 25mm at some point, but if olympus does a smaller lens at f/1.8 and around $300, that would make me plenty happy.

What's so wrong with the 20 f/1,7...?

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They are definitely not "completely different designs." I'm not sure what you are seeing to lead you to think this. Look at every other diagram for all the other prime lenses on the micro four thirds chart. All of ​these​ are completely different designs.

I do not imagine that these are scale drawings. I take them to be schematic diagrams. I suppose there are specifications for the figure of each element listed somewhere. I suppose there may be slight differences in the figure for homologous elements in the two patents, but by and large these are the same lens design.

The real crux is this. The patent for the Sigma version of a 25mm f/1.4 lens was filed a month before the panasonic 25mm f/1.4 was released so it ​cannot​ be a matter of reverse engineering a ​similar ​design. Also, if you think about the number of permutations and combinations of wildly-shaped lens elements that ​could​ be used to make a 25mm f/1.4 lens, it seems the likelihood that Sigma came upon such a similar design entirely by chance is vanishingly small. Sigma knew that this was how the panasonic lens would be made. I think there are two possibilities 1) Sigma designed the lens or 2) Panasonic contracted for Sigma to manufacture the lens and Sigma ripped off the basic design and changed enough details of the design to obtain a "unique" patent.

Nothing is wrong with the 20mm f/1.7. If I had my druthers I'd get a 17mm and a 25mm though, instead of one lens in between the two. Actually I'd get a 17mm and the 60mm macro (or ​maybe the oly 45mm but probably the 60mm macro) first then think about maybe getting a 25mm sometime down the line.

Sorry for bringing this up again, I only read this today...

If you look at the Panasonic website, you will see they talk clearly of two aspherical mould elements, while the Sigma Patent, provided the translation is correct, speaks of "Two three-sided aspherical" (I think the translation messed up with things and it should have been 3 two sided aspherical lenses.) Either way, that is not the same.

Okay I'll address your other points. 1) "Two three-sided aspherical lenses" clearly doesn't make a whole lot of sense. So it's a mistranslation. You can ​think​ it should have been "three two-sided aspherical" but you don't know that do you? You're just guessing.

I too take the diagrams to be schematic, but there is enough indication that both or different. Just tweak a little and you have two completely different lenses. More over, there are just so many designs which one can apply to get a lans with the same specifications.

I don't agree with this statement. I think after a) more powerful computers, b) more sophisticated software and c) more advanced manufacturing capabilities made lens design much more an exercise in computerized optimization, the number of feasible designs for a lens at a particular focal length and aperture increased dramatically.

Or would you suggest that the Zuiko OM 50 f/1,4 and the Pentax SMC 50 f/1,4 are also from the same supplier?

No. These designs were based on time-tested combinations of lenses. Modern lens design is more exotic and depends on pretty sophisticated software to optimize the optics. It results in some pretty funky combinations which in my opinion makes it less likely that the sigma and panasonic 25mm patents could come from separate design efforts. If you can come up with another optical design that's as close to the panasonic 25mm as the sigma 25mm is I'd say you made your point. This example doesn't do it.

How very convenient to take out just one point, toss it over saying that computers don't do the same thing twice and leave everything else out to try to make your point.

Show me some lenses (not so-called "normal" lenses with symmetrical designs) that are substantially similar and I'll be more inclined to believe you. The Four Thirds and micro Four Thirds lens charts are convenient places to look because all the lens diagrams are displayed. If you look at all the standard zooms for instance, or the 40ish-150ish zooms for another for instance, there are genuinely some similarities there between some of the lenses, but ​no two lenses listed there are so strikingly similar as the sigma patent is to the panasonic lens that we're discussing.

I know that some very exotic glass didn't exist back in the seventies (when the Pentax and Olympus were developed) but they did already rely on computer design; what's the difference...?

The difference is in the degree of computer input versus human input.

(lost the qoute indent here.) "And no, I can't bring any other example for the simple fact that, to my knowledge, there doesn't exist any other 25 f/1,4 MFT...Olympus Zuiko OM 50mm f/1,4 scheme

Pentax SMC FA 50 f/1,4 scheme

I think that there are way to many people around here with too much time on their hands and too much imagination. The same applied for the Sony sensor in OM-D theory: while there is a possibility that this is true, I still think too this day that this is everything but proven...

Not that any of this matters, because the OM-D sensor is fabulous, whatever the make, and while I never used the PL 25 f/1,4 I think that is also a fabulous lens, whatever the make (Panny, Leica or Sigma...)

I agree with you here. There's really not much significance to this from the standpoint of how good the equipment is. It seems to me that the panasonic 25mm is a ​very​ good lens regardless of the designer.

I've just always questioned anyone who said that Leica had anything to do with the design of any lenses for Panasonic and this seems to support my point of view.

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