Forgot Password
Pentax Camera Forums Home
 

Closed Thread
Show Printable Version Search this Thread
06-14-2014, 12:18 PM   #301
Senior Member




Join Date: Dec 2013
Location: Hamburg
Posts: 287
QuoteOriginally posted by ElJamoquio Quote
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

06-14-2014, 12:19 PM   #302
Pentaxian
jsherman999's Avatar

Join Date: Dec 2007
Photos: Gallery
Posts: 8,228
QuoteOriginally posted by Pål Jensen Quote

"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 ----------

QuoteOriginally posted by Pål Jensen Quote

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!! ?

Last edited by jsherman999; 06-14-2014 at 12:27 PM.
06-14-2014, 12:29 PM   #303
Site Supporter




Join Date: Feb 2011
Posts: 4,892
QuoteOriginally posted by eyeswideshut Quote
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.
06-14-2014, 12:31 PM   #304
Pentaxian
jsherman999's Avatar

Join Date: Dec 2007
Photos: Gallery
Posts: 8,228
QuoteOriginally posted by eyeswideshut Quote
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

06-14-2014, 12:41 PM   #305
Pentaxian




Join Date: Apr 2007
Location: Romania
Posts: 8,424
But ElJamoquio "knows" because of "true equivalence" that FF is cheaper... interesting how you didn't explained this to him.

QuoteOriginally posted by ElJamoquio Quote
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.
06-14-2014, 12:57 PM   #306
Site Supporter




Join Date: Feb 2011
Posts: 4,892
QuoteOriginally posted by Kunzite Quote
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!
06-14-2014, 01:08 PM   #307
Senior Member




Join Date: Dec 2013
Location: Hamburg
Posts: 287
QuoteOriginally posted by jsherman999 Quote

QED
So it is the difference between 'equivalent' images and 'identical' images.
Equivalence accounts for equivalent (but non-identical) images: a tautology.
QED
06-14-2014, 01:11 PM   #308
Pentaxian




Join Date: Apr 2007
Location: Romania
Posts: 8,424
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.

06-14-2014, 01:22 PM   #309
Site Supporter




Join Date: Feb 2011
Posts: 4,892
QuoteOriginally posted by Kunzite Quote
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!
06-14-2014, 01:27 PM   #310
Pentaxian
jsherman999's Avatar

Join Date: Dec 2007
Photos: Gallery
Posts: 8,228
QuoteOriginally posted by normhead Quote
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?


QuoteQuote:
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....

.
06-14-2014, 01:33 PM   #311
Senior Member




Join Date: Dec 2013
Location: Hamburg
Posts: 287
QuoteOriginally posted by ElJamoquio Quote
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.
06-14-2014, 01:39 PM - 1 Like   #312
Senior Moderator
Loyal Site Supporter
Parallax's Avatar

Join Date: Apr 2008
Location: South Dakota
Photos: Gallery
Posts: 15,107
We've gone from the sublime to the ridiculous with this thread.
This is the second time it's degenerated into a slap fest.


:closed:

Last edited by Parallax; 06-14-2014 at 01:53 PM.
Closed Thread

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
24x36mm, asp-c, bit, camera, canon, control, dof, equipment, f/2.8, ff, film, format, frame, full-frame, lenses, lot, medium, pentax, people, photographer, pm, resolution, sensor, skill, thread, thread title, view
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentax ff and why do I need that. soled Welcomes and Introductions 6 02-20-2015 03:50 AM
Filters, do you really need them? peterjcb Pentax DSLR Discussion 17 01-16-2014 06:10 PM
Do i really need a FF DSLR simple mick Pentax DSLR Discussion 21 12-26-2012 07:02 PM
Do you really want a FF??? i83N Photographic Industry and Professionals 48 10-09-2012 01:52 PM
Why Do You Want FF? tkj365 Photographic Industry and Professionals 193 09-26-2012 11:09 PM



All times are GMT -7. The time now is 03:16 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top