perspective vs. field of view

[Finder]

Which image has more depth? (Perspective is simply the apparent depth in an image.)

 

[ferider]

Say you take photo (A) with a perfect 35mm lens. Then take photo (B) from the same viewpoint of the same object with a 50mm lens. WRT perspective, the outcome will be identical compared to a (A) cropped 1.4x, and in print enlarged by the same factor.

Why you like the same lens when moving from one format to the next, Joe, must have to do with the lens, not any photographic parameter, like FOV, perspective, etc 🙂

Roland.

 

[Finder]

The best way I can describe it is like this. Think of the two formats like looking through two windows at the same tree. One of the windows is DX (cropped); the other is FX (24x36) full frame. Just because the tree occupies more space in the smaller window, it doesn't mean the tree is any closer. It just means there is less area around the tree compared to the big window (24x36).

This is wrong for two reasons.

1. You are not then enlarging the frames to be the same size.

2. Perspective is not simply the relationship between foreground and background object size. The entire frame is use to give depth.

 

[januaryman]

Dear Frank,

True, and I've never seen why. Common experience: telephotos compress perspective, wide-angles stretch it.

Cheers,

R.

That's the first thing in this discussion that I've managed to understand and agree with. Thanks for that simple answer.

 

[ferider]

Common experience: telephotos compress perspective, wide-angles stretch it.

That's the first thing in this discussion that I've managed to understand and agree with. Thanks for that simple answer.

The interesting part is that cropping and enlarging by the same factor does the same (compression).

 

[Nikkor AIS]

Finder, hmm.

Nothing you said in your two points leads me to think that what I said is wrong in any way 🙂.

The tree doesn't get closer, just because the window is smaller.
It's time for me to go outside and look at some trees.

 

[Finder]

Finder, Hmm

Nothing you said in your two points , leads me to think in any way, what I said is wrong.🙂

The tree dosnt get closer, just because the window is smaller.
It's time for me to go outside and look at some tree's.

Well, go and look at my example. It clearly proves perspective changes with cropping.

 

[Paul Luscher]

More photo opps is what I crave.

 

[charjohncarter]

Wouldn't it make more sense to talk about DOF in the print and not the film/sensor plane?

I'd like to hear the analogies used on this too.

 

[mto'brien]

I find this to be a useful visual:

If I am using a cropped sensor and I move the camera back to get the same view as a FF, and I don't change the aperture, I am then effectively changing the DOF, correct?

-Matt

 

[Finder]

For those who want to rewrite perspective to be just object distance. Can you tell the difference in perspective from these images?

 

[Frankie]

The native FoV, a property of the lens, does not change.

The effective FoV depends on cropping...at the sensor or in wet-printing.

Perspective is a function of camera-to-subject distance, given a focal length.

Perspective will be different when one changes camera-to-subject distance [steps back] or focal length [to shorter] to regain effective FoV lost to sensor crop-factor.

[There is a body of mathematics defining the above in my field...predating "crop-factor" talk by about 4 decades.]

I think it is the talk of "35mm [format] equivalent focal length" prevalent in digital camera reviews that confuses most.

 

[shadowfox]

I think I am agreeing with Finder.

1. Perspective is the relationship of two objects within a frame. If you only have one object, use the horizon as the second one (infinity distance).

2. Changing lens focal length also changes perspective. Because it changes the *viewing angle*. This is a good illustration of this point.

3. Cropping at the sensor plane, does not change perspective. Because we are cropping a projected image, not altering the physical construction of the lens to give us less viewing angle.

Therefore if I pick up a smaller-than-full-frame sensor body, and mount a 24mm full-frame lens that is designed to give me 84 degrees of viewing angle, the picture that I get will have the same perspective (84 degree viewing angle) but smaller in physical size (not in megapixel size, that depends on the sensor resolution).

So it is not quite the same as using a real 36mm lens (assuming 1.5x crop factor) which only gives me about 64 degrees of viewing-angle --> therefore different perspective.

Make sense? 🙂

PS: DoF are tied to perspective, if you don't change the perspective, you are not changing the DoF.

 

[Finder]

There seems to be a disconnect about perspective to those whose field is drawing and painting and whose field is photography and imaging. The standards in one field do not always translate to another. The Focal Encyclopedia of Photography, a fairly common and mundane source, covers the topic adequately.

 

[Andy Kibber]

What we really REALLY want to know is whether depth of field changes on cropped-sensor cameras! :angel:

:bang::bang:

 

[Finder]

What we really REALLY want to know is whether depth of field changes on cropped-sensor cameras! :angel:

:bang::bang:

No you don't.

 

[shadowfox]

What we really REALLY want to know is whether depth of field changes on cropped-sensor cameras! :angel:

:bang::bang:

Andy, read my explanation above. You'll find your answer. 😀

 

[shadowfox]

There seems to be a disconnect about perspective to those whose field is drawing and painting and whose field is photography and imaging. The standards in one field do not always translate to another. The Focal Encyclopedia of Photography, a fairly common and mundane source, covers the topic adequately.

Not really, perspective is perspective in both fields.
Maybe it's how we learn or use the term that causes confusion.

 

[back alley]

Say you take photo (A) with a perfect 35mm lens. Then take photo (B) from the same viewpoint of the same object with a 50mm lens. WRT perspective, the outcome will be identical compared to a (A) cropped 1.4x, and in print enlarged by the same factor.

Why you like the same lens when moving from one format to the next, Joe, must have to do with the lens, not any photographic parameter, like FOV, perspective, etc 🙂

Roland.

first let me thank roland for addressing the main point of my original post.

and then apologize to all for i fear my question might have been phrased poorly.

i like 35 mm lenses, i assume it is the pov that i like.
when i use a 21mm lens on the rd1 to get close to that 35m pov it seems 'off' to me.
when i use a 35mm lens on the rd1 - which gives me a pov of a 50mm lens, i like it.
but normally i don't care for 50mm lenses in general.
so it seems to me to be that it's the 35mm lens that i like no matter which camera it is on.

i am trying to understand why this is?!

 

[Finder]

Not really, perspective is perspective in both fields.
Maybe it's how we learn or use the term that causes confusion.

Apparently not. I was told by an expert in painting and drawing that I am dead wrong in my definition of perspective. My field of expertise is photography and imaging. The definition is quite clear if you have actually studied it. There is no ambiguity.