Bob,
You are right , I did just "Jump In". In fact i thought I was answering an e-mail from Qkano, not from Bob. Now that I have reread the e-mail I still have difficulty I distinguishing your comments from Qkano's.
My thoughts were presented in jest only. No rebuttal intended. I forget that subtle or sarcastic humor never comes through in the e-mail format. I apologize for my comments.
I "Jumped In" because I thought the the post by Qkano/Bob were putting down the exercise as flawed, unworkable, and a waste of time-not something fun to play with.
Upon careful rereading of your comments I agree with your points. In fact, in the first image taken with a normal (4 x 5) lens the camera position (LAP) is downhill from the front door of the church (which should be the LAP) and backing off with a longer lens would still keep the church high in the image unless you had a very tall tripod or there was a convent hilltop behind you on which to stand.
I saw the exercise as simply a way for beginning photography students to understand how the sizes of objects in a picture change as camera position changes relative to subject and background. I didn't spend much time studying the exercise. I just figured that if the first photo was made with a 150mm lens then you could create the second photo by backing off and using a 300mm lens. Nothing exact or precise in my thinking, just a quick summation based on shooting a lot architectural work with 4x 5. In fact I am unable to do the math needed to solve the problem. That's why I went to The Art Center College of Design and not RIT. (this is said in jest, so no harsh comments please).
Again, please accept my apologies, Walter
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Walter wrote:
No lies, no enlargements, no untruths, no flaws in the question-just straight photos.
Think of the two images as 4 x 5 contact prints.
Moving back from an image will always make the background appear to be higher in the frame without any elevation of the camera's position. The height of the building is now less as compared to the mountains in the background
Been there done that! But I haven't a clue as what the longer focal length is or how far back the camera was moved.
Walter
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On Friday, August 13, 2004, at 04:35 AM, wildimages@xxxxxxxxxxx wrote:
Walter.
I'm wondering how to respond to your categorical rebuttal of my "answer".
In part it's almost as if you didn't read it before jumping in.
To put the meat first:
I've constructed a third image showing what the image should have looked
like had the camera really been moved away from the church along the line
of the viewpoint(VP)/look-at point (LAP) axis with no elevation.
http://website.lineone.net/~wildimages/PF/perspective2.jpg
The two frames on the left have merely had a "+" added centrally to indicate
the position of the LAP.
In the frame on the right I have scaled the background (mountains) and forground
(everything else) elements by the factors to account for focal length first
and moving back - keeping the same LAP.
Note1: there is no evidence of convergence in the tower or gable end of
the church so I've assumed the camera was held horizontal.
Note2: in reality not all of the "forground" elements would have been at
the same distance. The tower in fact is clearly eclipsed by the roof for
instance.
Anyway: compare the right and centre frames and at least you can see how
what was presented compared to what I would have expected to see!!!!
Now to deal with the apparent rebuttal*********
<<No lies, no enlargements, no untruths, no flaws in the question-just straight photos.>> Well, that sounds like a rebuttal to me!!!!
Think of the two images as 4 x 5 contact prints.The question certainly said 4 x 5. The question certainly said uncropped.
So exacly how do you explain why the aspect ratio of the two "photos" in
the question were nowhere near 1:1.25?
Can you really not see any discrepancy? If not, I guess there's no point
in trying to convince you otherwise.
Note: this didn't take me a lot of thought: it just jumped out as wrong
when reading the blurb.
<<Moving back from an image will always make the background appear to
Be higher in the frame without any elevation of the camera's position.>>
You used the word "always" not me: frankly that is patent nonsense. Any
part of the background that lies below the line between the camera and the
"look-at point" will actually appear to be lower. Indeed, without zooming
in (using a longer focal length) moving back will make all parts of the
original image move in towards the centre of the frame, the amount they
move in being inversely proportional to the distance from the camera.
<<<The height of the building is now less as compared to the mountains in
The background>>>
Well, that of course is true - but it still does not justify your rebuttal
for the reasons I will explain below.
<<<Been there done that!>>>
So have I, I've also thought about it a lot and played with 3D models ...
<<<But I haven't a clue as what the longer focal lenght is or how far back
the camera was moved.>>>
I had a feeling for the answer even before I did the calculations. Perhaps
I should get out more.
This was only supposed to be a bit of fun.
Bob
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