Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-12-2012, 08:21 PM   #16
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by Farmer_Terry Quote
I am not at all sure about that one - perspective was something that artists came to understand long before the camera was invented.
Precisely. That is proof positive that perspective has nothing whatsoever to do with focal legnth, or with lenses at all, but is - as artists have known for centuries - dependent pnly on position.

QuoteQuote:
If I stand in the corner of a room with a wide angle lens, the resulting image distorts the room making it feel larger than it will look to my eye.
Not exactly. That's only true if you view the image from to great a distance. What makes a lens "normal" is if its images look right when viewed from the distance at which people typically view that size image. And this is not dependent on the focal length of the lens per se, but on its field of view. A 35mm lens on APS-C has the same FOV as a 50mm lens on FF, and hence their images will be look normal when viewed at the same distances.

03-13-2012, 03:14 AM   #17
Veteran Member
westmill's Avatar

Join Date: Jan 2012
Location: Stoke on Trent
Photos: Gallery | Albums
Posts: 1,146
This is also why I often say a wide angle to normal lens is more useful than a long zoom.
Sensor quality in todays cameras is so great it makes cropping perfect.
With cameras like the K5 fitted with a 50mm F1.4 you can crop easily to equal 200mm
zoom with enough quality left to make a sharp 13" x 19" print.
Then you can tell everyone you have a 200mm F1.4 !!!!!!
03-13-2012, 03:47 AM   #18
Veteran Member
westmill's Avatar

Join Date: Jan 2012
Location: Stoke on Trent
Photos: Gallery | Albums
Posts: 1,146
In the real world though, all this is a bit of a whimsical nonsense.
Simply because focal lengh does indeed affect percieved perspective.
Landscape photographers often use lont tele lenses to compress perspective.
As do sports photographers in some situations. Using a lont tele lens pointing at a group
of bikers makes it look like they are almost on top of one another adding to the excitement
of the pic. Where in reality there is probably 20ft between each bike.
The clue is in the perceived bit !
03-13-2012, 04:34 AM   #19
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
QuoteOriginally posted by westmill Quote
Simply because focal lengh does indeed affect percieved perspective.
Landscape photographers often use lont tele lenses to compress perspective.
As do sports photographers in some situations.
Sorry, this just isn't the case. Perspective depends entirely on location, the lens-to-subject-to-context distances. The focal length merely crops the image to the frame. Distance determines perspective; focal length determines FOV; those plus aperture (and some other factors) determine DOF.

Let's say I aim my DA18-250 at your string of cyclists. I shoot at 18mm, then again (quickly) at 135mm, then again at 250mm. If I crop the 18mm and 135mm shots so they have the same FOV as the 250mm shot, they'll have exactly the same perspective. It's just as if we've clipped a photo from a magazine and drawn three nested boxes on it, the box sizes corresponding to the FOVs. Narrower FOVs see less of the image; but the perspective, the relationships of image elements, remains the same.

03-13-2012, 04:56 AM   #20
Veteran Member
westmill's Avatar

Join Date: Jan 2012
Location: Stoke on Trent
Photos: Gallery | Albums
Posts: 1,146
QuoteOriginally posted by RioRico Quote
Sorry, this just isn't the case. Perspective depends entirely on location, the lens-to-subject-to-context distances. The focal length merely crops the image to the frame. Distance determines perspective; focal length determines FOV; those plus aperture (and some other factors) determine DOF.

Let's say I aim my DA18-250 at your string of cyclists. I shoot at 18mm, then again (quickly) at 135mm, then again at 250mm. If I crop the 18mm and 135mm shots so they have the same FOV as the 250mm shot, they'll have exactly the same perspective. It's just as if we've clipped a photo from a magazine and drawn three nested boxes on it, the box sizes corresponding to the FOVs. Narrower FOVs see less of the image; but the perspective, the relationships of image elements, remains the same.
Yes you are correct and I understand all of this too.
But ! in reality it creates an optical illusion.
Perspective is about things looking right to the mind.
Things close up seem big and things far away get smaller as we see them. An artist can play with perspective simply by creating an imaginary dot and place it anywhere as the vannishing point.
If you draw a line of trees vanishing to a dot in the distance and then draw a man at the end the man looks like the jollie green giant has made an appearance.
Its an optical illusion. You can play with perspective to create sureal pictures. Its the fact that we dont ever see our pics at the right size at the right distance that creates the illusion. Mathamaticly it is indeed correct as I have already said. Im not arguing the fact that this is correct. But in reality we see an optical illusion because we dont see the print at the right size and distance.
Hence.... perceived perspective !!!!! as opposed to actual perspective !
03-13-2012, 05:46 AM   #21
Veteran Member
westmill's Avatar

Join Date: Jan 2012
Location: Stoke on Trent
Photos: Gallery | Albums
Posts: 1,146
Its a bit like arguing we walk at 850mph when walking in the right direction because the earth spins at 845 mph. Its true.... but its also a whimsical nonsense in everyday reality.
03-13-2012, 06:42 AM   #22
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
QuoteOriginally posted by westmill Quote
Yes you are correct and I understand all of this too.
But ! in reality it creates an optical illusion.
Perspective is about things looking right to the mind.
Things close up seem big and things far away get smaller as we see them. An artist can play with perspective simply by creating an imaginary dot and place it anywhere as the vannishing point.
If you draw a line of trees vanishing to a dot in the distance and then draw a man at the end the man looks like the jollie green giant has made an appearance.
Its an optical illusion. You can play with perspective to create sureal pictures. Its the fact that we dont ever see our pics at the right size at the right distance that creates the illusion. Mathamaticly it is indeed correct as I have already said. Im not arguing the fact that this is correct. But in reality we see an optical illusion because we dont see the print at the right size and distance.
Hence.... perceived perspective !!!!! as opposed to actual perspective !
Both are still about the distance in one way or another not about the focal length directly.
03-13-2012, 06:53 AM   #23
Veteran Member
westmill's Avatar

Join Date: Jan 2012
Location: Stoke on Trent
Photos: Gallery | Albums
Posts: 1,146
QuoteOriginally posted by Anvh Quote
Both are still about the distance in one way or another not about the focal length directly.
Talk about missing the bus

03-13-2012, 11:10 AM   #24
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
If so then once again shows how confusing you're or are you contradicting yourself with the last few comments?
03-13-2012, 12:41 PM   #25
Veteran Member
westmill's Avatar

Join Date: Jan 2012
Location: Stoke on Trent
Photos: Gallery | Albums
Posts: 1,146
QuoteOriginally posted by Anvh Quote
If so then once again shows how confusing you're or are you contradicting yourself with the last few comments?
Realy ? errrrr ok
03-13-2012, 03:19 PM   #26
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
Yes, don't you see it?
You can make fun about it since it's at your own expense but it isn't helpful.
03-13-2012, 05:37 PM   #27
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by westmill Quote
In the real world though, all this is a bit of a whimsical nonsense.
Simply because focal lengh does indeed affect percieved perspective.
Yes, because of the phenomenon I described already: a print from a wide angle lens would have to be viewed at an unnaturally close distance in order to look "normal", and a print from a telephoto lens would have to be viewed at an unnaturally far distance in order to look "normal".

But the relevant point here is, none of this is actually dependent on focal length per se - it is dependent on field of view. So it is a 35mm lens on APS-C that would produce the same lack of perspective distortion that a 50mm lens would on FF. The OP was confused on this point.
03-14-2012, 12:57 AM   #28
Junior Member
Farmer_Terry's Avatar

Join Date: Feb 2011
Location: Derby, UK
Posts: 32
Original Poster
Enough already. Aren't you just arguing semantics? You are both right.

The fact is that if I show the photograph of a group of bikers on a track to the classic man on the Clapham omnibus he will not ask what sort of lens I used, where I stood, or whether I cropped it from a much larger shot - he will just see an exciting bunch of bikes close together.

So yes, perspective does depend entirely on where you stand, but yes, lens length does affect perceived perspective. Two different things.
03-14-2012, 02:36 AM   #29
Veteran Member
westmill's Avatar

Join Date: Jan 2012
Location: Stoke on Trent
Photos: Gallery | Albums
Posts: 1,146
QuoteOriginally posted by Marc Sabatella Quote
Yes, because of the phenomenon I described already: a print from a wide angle lens would have to be viewed at an unnaturally close distance in order to look "normal", and a print from a telephoto lens would have to be viewed at an unnaturally far distance in order to look "normal".

But the relevant point here is, none of this is actually dependent on focal length per se - it is dependent on field of view. So it is a 35mm lens on APS-C that would produce the same lack of perspective distortion that a 50mm lens would on FF. The OP was confused on this point.
Thank you Mark,
Like Ive always said, Ive always understood this,
I was just pointing out that in practicality focal lengh
does indeed give at least the appearence of changing
perspective, which I think is actualy more relevent.
I figured the OP seemed to have grasped the idea
already that it doesnt do it litraly.
I just see it as a story of two halfs
03-14-2012, 08:21 AM   #30
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
Except that focal length does NOT determine perspective (and there's no difference between 'real' and 'apparent' perspective). ONLY distance determines perspective. Focal length determines FOV, the 'crop' of the image. Those who call the crop 'perspective' misuse the term. We've already gone over that shooting with different focal lengths from the same distance produces pictures with exactly the same perspective, the same relationships between objects in the image. That's just basic optics. Arguing around it does no good.

We can't even blame this on Anglish common-usage vs tech-jargon. If we use a phrase like "It seems to me from my perspective that..." we mean "This is how I see things from where I stand", i.e. at a fixed relationship to the observed, i.e. distance. Perspective is how things look from a certain distance, nothing more, nothing less. Yes, we may use longer lenses to try to annihilate that distance, but the perspective remains the same.

Last edited by RioRico; 03-14-2012 at 08:30 AM.
Reply

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!
50mm, camera, cameras, film, k-x, lens, pentax help, photography, question, sensor
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
focal length on crop sensor question? littledrawe Troubleshooting and Beginner Help 14 09-28-2011 03:06 AM
focal length pentax k-x Photographic Technique 9 11-22-2010 12:41 PM
focal length ewig Troubleshooting and Beginner Help 11 07-23-2010 09:32 PM
focal length landscaped1 Troubleshooting and Beginner Help 48 05-05-2010 03:04 PM



All times are GMT -7. The time now is 03:23 PM. | 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