[ChristianRock]

Take a look at the Sigma line and see if there is a smaller prime in the line-up. The smallest probably reflects the size of the motor module.


Steve

The Sigma 19mm and 30mm FE lenses have DN motors and are quite smaller...

There's other question here that one might ask... why is the smallest Sigma lens with a motor the only reference? Motors are not rocket science, if one company can make them smaller, other companies can as well. Especially Sigma which has a habit of reverse engineering everything!

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Last edited by ChristianRock; 05-19-2020 at 10:08 AM.

[normhead]

There was an article a few years ago where a Sigma rep was talking about the Sigmas getting bigger issue. Apparently Sigma engineers would design something to the original spec., then they would go to management and say "if we can add this and this we can accomplish this and this., and according to this source management almost always went for it. Hence Sigma lenses got bigger and bigger. The point being, every time they added an element or more weight, there was a design feature that supported that addition that could be presented to management. You can infer, nothing was added that did not provide some benefit.

[ChristianRock]

I was not aware that I had proposed findings.



Indeed, respectfully it's non-scientific. You can't trust these lens drawings to be a perfectly accurate representation of the reality. An approximation, sure, not a reliable benchmark.



Let's apply Occam's razor. You see the lens as being larger/heavier. It could be because the company pulled a "Beats audio" and artificially added useless elements to make it bigger / heavier. Or it could be because the designers did need that volume for the lens to deliver what they intended.

I have not opened any Art lens. I have not seen an actual, usable lens design ray tracing file. Or a STEP file rendering. Or whatever. I do know that guys like lensrentals, who regularly open up lenses, would have a field day of reporting dummy elements, wasted volume, or anything else on that line.

If the Art lens is that way, it's because the company didn't find a way to make it smaller.

It's hard to have an honest conversation when you misrepresent things I say with the intent to mock me. I really don't appreciate that.

Earlier you affirmed that I said that they made the glass elements unnecessarily larger. I never said that.

Now you're saying I said they are making the lens heavier than necessary when I never mentioned weight at all.

And who talked about dummy elements or anything of the kind.

I'm talking about tolerances and yes, wasted volume or gaps, which happens in engineering all the time. Remember the famously reported incident of Steve Jobs throwing an early iPad into his fishtank in the presence of his engineers, making them see all the air bubbles that came out of it, and yelling at them "as you see, you haven't made this nearly as small as you should!"?

Stop being dishonest and stop mocking people for asking honest questions - that you might not agree with, but that's your problem. I thought you actually represented this site in a way and I don't think you're doing a good job of it.

You think that just because you have the title of "optical engineer" that you are so much smarter and can look down on people here, but I see you saying things that are not smart at all.

If the Art lens is that way, it's because the company didn't find a way to make it smaller.

I had to single out this one phrase. Just stop and think about what you said and see if that makes any sense... and if it's even up to you to affirm something like that.

[stevebrot]

The Sigma 19mm and 30mm FE lenses have DN motors and are quite smaller...

Note that neither are SLR lenses...different design constraints. Different motor tech too.

why is the smallest Sigma lens with a motor the only reference?

Sorry, I should have been more specific and at least limited to HSM SLR models. Sigma, along with most other makers, uses shared modular construction principles across their lines and lenses sharing a particular motor type probably share the same module and require similar diameter and additional length to accommodate.

I will affirm too, that the 30/1.4 Art, while bigger than my FA 35/2.0*, is hardly a large lens; just as the DA* 55/1.4 size is not objectionable.


Steve

* Ironically, a little larger than the FA 50/1.4. The FA 35/2.0 has a more sophisticated design. Strangely, the FA 31/1.8 Limited is larger than either of them.

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Last edited by stevebrot; 05-19-2020 at 11:14 AM. Reason: Changed mind

[normhead]

I had to single out this one phrase. Just stop and think about what you said and see if that makes any sense... and if it's even up to you to affirm something like that.

The distance between lens elements is determined by the formula. You make them optimum for performance, not bigger not smaller.

I am reminded of the line from Amadeus. "That melody has too many notes."
And the reply "it has neither more nor less than needed."

[ChristianRock]

The distance between lens elements is determined by the formula. You make them optimum for performance, not bigger not smaller.

I am reminded of the line from Amadeus. "That melody has too many notes."
And the reply "it has neither more nor less than needed."

I quite agree with Mozart's statement in regards to music. And in this discussion, maybe other are discussing whether anyone's optical formula is too big but I"m not... I think most people in fact will tell you that either one of these lenses is not corrected enough wide open. I'm fine with my Sigma 30 1.4 Art the way it is ...

What I was talking about is the distance on the "sides" of the optical path, so to say.

Maybe another totally non-scientific image will explain better... still, even if it's not perfectly up to scale, it's not that far from reality, either.



From the optical elements to the side walls of the lens, there's quite a bit more going on, on the sides of the Sigma. That is basically what I have been trying to say from the beginning...

[bdery]

It's hard to have an honest conversation when you misrepresent things I say with the intent to mock me. I really don't appreciate that.

Stop being dishonest and stop mocking people for asking honest questions

I never, ever intended to mock anyone. Not in this case, nor ever. I purposefully used the word "respectfully". And when replying to the original poster, I wrote "I never laugh at someone interested in learning" in reply to the "don't laugh at me" comment.

If you have been offended, then I sincerely can say I am sorry. I don't think I wrote anything offensive, but you apparently disagree.

I thought you actually represented this site in a way and I don't think you're doing a good job of it.

I do write for Pentaxforums, but I am not a moderator or anything of the sort.

You think that just because you have the title of "optical engineer" that you are so much smarter and can look down on people here, but I see you saying things that are not smart at all.

That I will not agree with. I have never looked down on anyone. Not here or anywhere.

I am not smarter than others. More knowledgeable than most regarding optics, yes. That's not a flaw.

You did not say larger or heavier, true. I inferred that this was what you meant when you used the word "bigger". Maybe that's how my brain works today, maybe that's the language barrier, maybe that's just what I would have understood any day of the year.

Just stop and think about what you said and see if that makes any sense... and if it's even up to you to affirm something like that.

I still believe it makes sense. I did not say the lens is the smallest anyone could have made it. I'm saying if the company had found a way to make it smaller, they would have done so (within budget, time constraints, performances requirements). It is not sensible for a lens manufacturer to make a product larger for no practical reason. I'm saying I am confident that at no point in a project management meeting, someone stood up and said "let's add empty space in there".

You can disagree with my opinion of course, that's fair.

[ChristianRock]

Thanks for the explanation bdery. I'm sorry if I misunderstood you but you did come across in a dismissive manner, and perhaps that was not your intention.

Well, let's take two lenses from the same manufacturer.

First, a Zeiss Macro Planar 50 f2:


And a Zeiss Planar 85 1.4:


(I can't find anything from Sigma by the way)

Would anyone argue against the fact that the first lens was made bigger on purpose by leaving empty spaces on the sides of the barrel (in this case I assume to have a "built-in lens shade" in front by receding the front element quite a bit)? And that it's not "made as small as they could make it"?

[normhead]

Thanks for the explanation bdery. I'm sorry if I misunderstood you but you did come across in a dismissive manner, and perhaps that was not your intention.

Well, let's take two lenses from the same manufacturer.

First, a Zeiss Macro Planar 50 f2:


And a Zeiss Planar 85 1.4:


(I can't find anything from Sigma by the way)

Would anyone argue against the fact that the first lens was made bigger on purpose by leaving empty spaces on the sides of the barrel (in this case I assume to have a "built-in lens shade" in front by receding the front element quite a bit)? And that it's not "made as small as they could make it"?

I'm not seeing how they could make it smaller. Where is your supposed savings to be had?
I see a built in lens hood. It should either be built in or attached afterwards. Does that even matter? I guess if you count the lens hood on one and not on the other you can argue one is unnecessarily bigger.

They clearly saw too many Nikon and Canon shooters with the lens hoods reversed and decide to do something about it.
The most efficient design saves money. Extra weight and bulk costs money. What is the pay off for including extra weight and bulk?

IN the first, the whole lens assembly is designed to move as a unit. There has to be space for it to nest into the front assembly. That's not waste space. That's a mechanical necessity. To say anything for certain you'd have to see it move.

You could assume this lens has extra space in it, until you watch it move. It looks to me like things are crammed int there tight enough to make assembly difficult. It's not like making baseball bats.


I'm not so sure why this is so important.

[RICHARD L.]

The Zeiss Macro Planar 50 mm f/2 lens merely needs a barrel that provides lots of mechanical extension to achieve 1:1 or 1:2 magnification ... This is what is evident here. Form always follows purpose.

[bertwert]

I feel like there's a lot of wasted space in my DA 40 XS, obviously those silly Pentax engineers could have made it smaller.

[normhead]

I feel like there's a lot of wasted space in my DA 40 XS, obviously those silly Pentax engineers could have made it smaller.

I lost that lens. It was too small. I have no idea where it ended up. If it was twice the size I'd probably still have it.

[stevebrot]

Would anyone argue against the fact that the first lens was made bigger on purpose by leaving empty spaces on the sides of the barrel (in this case I assume to have a "built-in lens shade" in front by receding the front element quite a bit)? And that it's not "made as small as they could make it"?

It is a macro lens and made that way by design to allow extension and provide depth (protection and shade) for the front element. It is not made that way to make it look bigger or for marketing appeal. All three of my macro lenses are like that.


Steve

[Sandy Hancock]

I suspect Sigma lenses are generally bigger because they aim to undercut the prices of the OEM lens makers.

Spending the extra R&D and engineering money on minimising excess space is simply not a business priority.

[pepperberry farm]

I feel like there's a lot of wasted space in my DA 40 XS, obviously those silly Pentax engineers could have made it smaller.

I bet I could fit at least two more SMU's in there....