[eyeswideshut]

If Voigtlander designed and built a 50mm f/1.8 with the exact same parameters as the 25mm f/0.95, the two systems would produce pictures that would be indistinguishable. I have no idea what that old Olympus lens does and I don't need to know.

This is the vaporware forum, if you recall.

You do appreciate that a 50mm f/1.4 will necesarily be of a different optical construction than a 25mm f/0.95?
Therefore their character (that is everything NOT encompassed by equivalism) will be different.
Simple.
QED

[jsherman999]

"All you do when increasing or decreasing the format while maintaining the angle of view is transposing the DOF scale towards thinner or deeper DOF". Which scale is "correct" is purely a subjective issue.
.

Where, in the concept of equivalence, does it say one side of the equation is more 'correct' than the other?

Describing a physical relationship between two things doesn't imply one of those things is 'correct' and the other isn't.

---------- Post added 06-14-14 at 01:26 PM ----------

Aperture - shutterspeed - Sensitivity = exposure

This tells you all you need to know and is the physics behind a photograph.
.

"All you ever need to know," huh? What if I have an m43 system, I want to buy an aps-c system and I want to know what lens to buy will perform the same as my 25mm f/1.8 m43 lens? Or how much I'd have to spend, minimum, to get about the same angle of view but more DOF control (and more noise-free images) than my 75 f/1.8 brings on m43? Or, for my typical style of shooting in which I need to maintain a certain minimum DOF, would it even make sense to upgrade to aps-c? Valid questions someone might ask?

Are those just the questions that must not be asked!! ?

[ElJamoquio]

You do appreciate that a 50mm f/1.4 will necesarily be of a different optical construction than a 25mm f/0.95?

That's why I was comparing a 50mm f/1.8 to a 25mm f/0.95. The optical construction could be precisely the same (I know because of equivalence!).

Simple, QED.

[jsherman999]

You do appreciate that a 50mm f/1.4 will necesarily be of a different optical construction than a 25mm f/0.95?
Therefore their character (that is everything NOT encompassed by equivalism) will be different.
Simple.
QED

QED

[Kunzite]

But ElJamoquio "knows" because of "true equivalence" that FF is cheaper... interesting how you didn't explained this to him.

That's why I was comparing a 50mm f/1.8 to a 25mm f/0.95. The optical construction could be precisely the same (I know because of equivalence!).

Simple, QED.

You know nothing. You're claiming the optical construction "could be precisely the same", because otherwise your "equivalence" wouldn't work.
But statements such as this makes "equivalence" looks like a sham. Two lenses with different focal lengths being "precisely the same"? Not in this Universe.

[ElJamoquio]

But ElJamoquio "knows" because of "true equivalence" that FF is cheaper... interesting how you didn't explained this to him.


You know nothing. You're claiming the optical construction "could be precisely the same", because otherwise your "equivalence" wouldn't work.
But statements such as this makes "equivalence" looks like a sham. Two lenses with different focal lengths being "precisely the same"? Not in this Universe.

This is the friendly Pentax forum!

[eyeswideshut]

QED

So it is the difference between 'equivalent' images and 'identical' images.
Equivalence accounts for equivalent (but non-identical) images: a tautology.
QED

[Kunzite]

ElJamoquio:
I'm not trying to be rude (though the constant refusal of listening to arguments is sometimes exasperating). I'm merely reminding you that in this Universe, two lenses with different focal lengths cannot be "precisely the same".
And I find it amazing that we have to argue about the laws of physics.

[ElJamoquio]

ElJamoquio:
I'm not trying to be rude (though the constant refusal of listening to arguments is sometimes exasperating). I'm merely reminding you that in this Universe, two lenses with different focal lengths cannot be "precisely the same".
And I find it amazing that we have to argue about the laws of physics.

Wow! OK! So if I had said 'precisely the same, but with all dimensions otherwise multiplied by a factor of 2' would you have understood?

I find it amazing that we have to argue about point of focus when comparing the theoretical aspects of a theoretical camera!

[jsherman999]

it's always been the flaw in the argument that you need FF for narrow DoF....

I wonder who made such an argument? Is it an imaginary argument you make up in these threads, something you claim to have heard?

The simple fact is, with an FF camera, I could have to reduce my shutter speed so much I got motion blur from the movement of the critter and I wouldn't have had a useful image instead of a keeper.

.

.

IMO... kinda noisy shot there, Norm....

.

[eyeswideshut]

Wow! OK! So if I had said 'precisely the same, but with all dimensions otherwise multiplied by a factor of 2' would you have understood?

I find it amazing that we have to argue about point of focus when comparing the theoretical aspects of a theoretical camera!

El J., you have noticed that different lenses have different character, render color, contrast, tone differently. Some think a lens 'paints', while another is surgically cold. One is 'flat' whereas another gives a three dimensional sense etc, etc. etc. This thing are largely non-quantfyable simply because they cannot be operationalized - you will hardly get two people to agree on any of this. Therefore none of these things are encompassed in the tenets of equivalence. It says, take these five factors and you will have an EQUIVALENT image - that does not mean an IDENTICAL image. And it is precisely for this reason that I believe that equivalence is not very useful - it claims too much and enlights too little.

[Parallax]

We've gone from the sublime to the ridiculous with this thread.
This is the second time it's degenerated into a slap fest.