Perspective based on distance, not lens?


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chanjyj

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Apr 8, 2007
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#1
Got this off from kenrockwell.
I cannot really make head or tail of what he is saying, but it seems to be correct yet uncorrect at the same time.

1st Paragraph seems a half-truth, if he would clarify it.
2nd Paragraph seems to be wrong?
3rd Paragraph is to complex to be understood unless I dissect the statement.

Perspective depends only on your position. It has nothing to do with your lens.

Shorter or longer lenses don't change perspective, they just make framing tighter or looser.

Different lenses require you to move closer or farther way to get the framing you want, but it's the change in position that alters perspective, not the lens.
For the record though, if there are any newbies reading this, don't get confused. Just play around with your lenses and you'll get pretty much used to them. Once practical is easy, the theory part becomes much easier to understand, not the other way around.

Regards
Chan
 

ortega

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Nov 2, 2004
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#2
nothing is clearer than an actual test



shot with a 18-70mm nikkor

on at 18mm and the other at 70mm (notice the dof)
camera was mounted on a tripod so that camera and subject is the same for both shots
try it! :)

this is a animated gif so give it some time to load
 

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flipfreak

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#3
his statements are only half truths. if u can move your position, then the focal length will give the same perspective. but then u will need to crop alot to get the same picture.
 

chalib

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Oct 4, 2007
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#4
He is a joker

And you go to his website for tutorial? Good luck to you :bsmilie:
 

chanjyj

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Apr 8, 2007
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#5
his statements are only half truths. if u can move your position, then the focal length will give the same perspective. but then u will need to crop alot to get the same picture.
yeah. Now re-reading his statements and your version of it I think I get his meaning.
But if a newbie reads this... good luck :dunno:
 

chanjyj

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#6
He is a joker

And you go to his website for tutorial? Good luck to you :bsmilie:
Don't be so close minded.
Do you stick to one website when browsing the web? ;)
 

chalib

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#7
Don't be so close minded.
Do you stick to one website when browsing the web? ;)
It's not close minded pal

Why to waste time reading while there are many good ones? :bsmilie:
 

Daedalus Trent

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Apr 15, 2008
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#8
It's not close minded pal

Why to waste time reading while there are many good ones? :bsmilie:
Have to agree :bsmilie:

His lens reviews are a great place to start...but if they're the only review you're gonna read, then good luck to you :p
 

gimumancer

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Sep 15, 2009
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#9
his statements are only half truths. if u can move your position, then the focal length will give the same perspective. but then u will need to crop alot to get the same picture.
his statements are all actually true, perspective has nothing to do with focal length, it is the subject to camera distance that determines the perspective, if you move your position, you will alter the perspective, focal length just changes your framing, you zoom in (increase focal length) so your subject fills the frame (sort of like just cropping your picture but keeping the same resolution), that's it, it also affects depth of field (longer focal length=shallower DOF)..the reason people thought focal length affects perspective is that when they use long focal length, they are forced to move (i.e. move back) around to get their desired framing and minimum focusing distance thus altering the perspective in the process..
 

lsisaxon

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Nov 29, 2004
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#11
Got this off from kenrockwell.
I cannot really make head or tail of what he is saying, but it seems to be correct yet uncorrect at the same time.
Perspective = viewpoint. ie, where your eye is when viewing a certain scene.

Focal length makes you change your viewpoint to get a certain composition. That's why it seems like focal length makes a difference but it actually doesn't if you refuse to move. This is demonstrated by ortega's Coco Pops.

That's also why PnS cameras have focal lengths in the range of just several mm. eg, ~6mm to give a 28mm 135-format equivalent FoV. This is because the sensor size is very much smaller.
 

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gimumancer

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Sep 15, 2009
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#12
As gimumancer said, all 3 statements are true. Trouble is, people often mix up "perspective" with "field of view"

This is an excellent explanation, with example photos:

http://www.mhohner.de/essays/myths.php#focalper
hi bro nice read on the common myths..but about myth #9, maybe a simpler revision of the myth is to change

"Tele-photo lenses have a shallow DOF"

to

"Tele-photo lenses have shallowER DOF"

and not

"Tele-photo lenses used at short distances and at wide apertures have a shallow DOF"

of course when we are comparing things, we should always keep most of variables constant so the revised sentence implies that assuming all things equal (aperture, distance), Tele-photo lenses have a SHALLOWER DOF compared to shorter lens..what you guys think?
 

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lsisaxon

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Nov 29, 2004
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#13
hi bro nice read on the common myths..but about myth #9, maybe a simpler revision of the myth is to change

"Tele-photo lenses have a shallow DOF"

to

"Tele-photo lenses have shallowER DOF"

and not

"Tele-photo lenses used at short distances and at wide apertures have a shallow DOF"

of course when we are comparing things, we should always keep most of variables constant so the revised sentence implies that assuming all things equal (aperture, distance), Tele-photo lenses have a SHALLOWER DOF compared to shorter lens..what you guys think?
20mm is telephoto on PnS. And 90mm on large format is wide angle.. So what do you think?
 

Dream Merchant

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Jan 11, 2007
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#14
Fixed laws, induced variables and relative applications ...

Speaking of large format, here's a very interesting discussion on the topic of 'Perspective': http://www.largeformatphotography.info/forum/showthread.php?t=49706&highlight=perspective

Note: The talk on raise and fall refers to moving a lens board relative to the film plane/position up and down (commonly known in 35mm terms as 'shifting' a lens up and down).

A 'Standard' refers to a frame or holder that holds the lens or groundglass (GG)/filmback. There's a front Standard (that holds the lensboard) and the rear Standard that holds the GG and filmback. In a view camera, both standards have an astoundingly large range of movement.

In discussions where the lens plane or the film/sensor plane is not able to be manipulated or moved aka conventional cameras and lenses, the discussion usually centers on altering the apparent sense of perspectives by physically moving the camera towards or from the subject and selecting an appropriate focal length lens to accommodate said subject and one's chosen composition. A lens' focal length nor DOF has absolutely nothing to do with altering perspectives.

However, in large format, the discussion becomes more complex because an operator IS able to alter the apparent sense of perspective and how an image is rendered on a film plane WITHOUT physical moving a camera closer to or further away from a subject.

Not many would go through all thirteen pages, but it's very interesting reading nonetheless.

OK, I hope I got at least part of that correct. My brains are still sleeping. :bsmilie:
 

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Dream Merchant

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Jan 11, 2007
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#15
Perspective depends only on your position. It has nothing to do with your lens.

Shorter or longer lenses don't change perspective, they just make framing tighter or looser.

Different lenses require you to move closer or farther way to get the framing you want, but it's the change in position that alters perspective, not the lens.
To get to the point, what KR said is absolutely true if my recollection of optical laws are correct (which is to say, not very much actually! :bsmilie:)
 

chanjyj

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Apr 8, 2007
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#16
If only KenRW wrote more clearly ;(
I understand now what he is trying to convey. But golly, must he write like that :dunno:

Anyway i think Michael Reichmann did a test on this to prove that wide angle lenses have same DOF as telephoto if you crop like crazy and subject size is the same (something to that extent, I read it about 2 years ago). Ended up sounding like what KRW is trying to say.
 

flipfreak

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#17
his statements are all actually true, perspective has nothing to do with focal length, it is the subject to camera distance that determines the perspective, if you move your position, you will alter the perspective, focal length just changes your framing, you zoom in (increase focal length) so your subject fills the frame (sort of like just cropping your picture but keeping the same resolution), that's it, it also affects depth of field (longer focal length=shallower DOF)..the reason people thought focal length affects perspective is that when they use long focal length, they are forced to move (i.e. move back) around to get their desired framing and minimum focusing distance thus altering the perspective in the process..
yes. fundamentally correct but it does not take into consideration the photography aspect. and thats what i don't like abt him sprouting photography rules. :thumbsd:
 

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