Does perspective change when you change the focal length?
Aug 21, 2018 12:25:36 #
Gene51 wrote:
Sure, look at the images that I posted. You need to learn the difference between vanishing points and perspective. They are not the same.
I did. I used them as you are supposed to to prove your point. They DISPROVE your point. And as to my "learning," dear man, vanishing points are essential to perspective.
Please enlighten us with your definition of perspective.
Aug 21, 2018 12:26:20 #
artBob wrote:
Superimpose the two pix. reduce opacity of each to 50%. Notice the offset of street, cars, houses. The perspective is changed.
I am pretty sure you don't understand minor differences in magnification, and how an uncorrected wide angle lens will have some distortions that will be different from a telephoto lens, thus preventing a perfectly registered image.
A perspective difference in the context of this discussion, is axial in nature. If there were such a difference in my images - then the image shot with the wide angle lens would have considerable extension distortion, where the elements closer to the camera would be depicted larger and would obscure more of the background. And conversely, the telephoto shot would have considerable compression. There is no such difference.
And your example merely shows that you forgot to use the Align Images command in Photoshop.
You would do well to take a course in optics and optical design so that you can fully comprehend the impact of lens aberrations on distortions in wide angle and telephoto lenses.
Pass the popcorn, Steve.
Aug 21, 2018 12:32:20 #
artBob wrote:
...Haven't seen one attempt at this besides mine, although this was the initial "test" that claimed to "prove" that focal length did not affect perspective.
That's absolutely not true. CaptainC and Gene51 both clearly demonstrated that only camera position determines perspective. You just chose to not believe them.
Even you proved it yourself:
You could not see the proof because of a little blur from distortion. You just could not believe your lying eyes.
artBob wrote:
I continue this discussion because (1) for a begin... (show quote)
You can come up with all sorts of excuses why others with more knowledge and experience than you don't see it your way. But it's clear that you are only deceiving yourself.
artBob wrote:
"You are entitled to your own opinions; you are not entitled to your own facts."
This is not a mater of opinion. It's a mater of fact. You are not entitled to your own facts. It's simple geometry. You cant argue with Euclid.
Aug 21, 2018 12:32:58 #
Aug 21, 2018 12:37:09 #
artBob wrote:
... as to my "learning," dear man, vanishing points are essential to perspective. ...
That's a bit condescending, isn't it?
Most scenes do not require vanishing points to support perspective.
You might be able to find them when there is architecture involved, but certainly not with portraits and rarely with landscapes unless you find a way to draw our silly lines all over the image.
Aug 21, 2018 12:43:40 #
Boy, this guy (I'm ashamed he's named Bob too) is a bona fide moron. I'm tapping out - while it's amusing to see him endeavor to prove his "truth" it is at this point most tiresome.
Let him get back tous after taking some courses in optics.
Let him get back tous after taking some courses in optics.
Aug 21, 2018 12:47:53 #
Gene51 wrote:
I am pretty sure you don't understand minor differ... (show quote)
Your "some minor distortions" are clearly distortions of perspective. It is hilarious to think that an algorithm designed to take out distortions (PS "Align Images") would "prove" your point.
Bottom line, DISTORTION admittedly occurs. I have used linear perspective to show that there is a difference in perspective. You suggest I take a course. I've taken several. Have you?
BTW, you alluded to "Axial perspective," apparently without understanding its relationship to linear perspective, the latter being the universally accepted way to show 3D on a 2D plane. Methinks it is not I who needs a course.
Aug 21, 2018 12:56:58 #
Aug 21, 2018 12:58:35 #
f8lee wrote:
Boy, this guy (I'm ashamed he's named Bob too) is a bona fide moron. I'm tapping out - while it's amusing to see him endeavor to prove his "truth" it is at this point most tiresome.
Let him get back tous after taking some courses in optics.
Let him get back tous after taking some courses in optics.
So, you are ashamed about a name, but not that you haven't SHOWN one proof?
I am amazed at how many people do not even try the experiment to see if it's true. As I said, I thought it might be, but the only way to actually know was to test it. I've done that three times now, including using the photos of the OP himself. The EVIDENCE has always DISPROVEN the statement.
As a teacher, I am saddened by the lack of critical thinking and reliance on selective authority shown here. THINK! TEST! it's sure better than personal attacks, which just show your weakness.
Aug 21, 2018 13:05:58 #
Gene51 wrote:
Of course will see different perspective - you b ... (show quote)
Great example Gene showing what almost all have been saying so far, but at this point, not sure anything will convince the naysayer(s).Aug 21, 2018 13:07:32 #
Steve Perry wrote:
Great example. ONLY position affects perspective, hopefully your post will lay this to rest.
Don't count on it ending anytime soon Steve.... its up to 8 pages now, and who knows how long this might go on.
Aug 21, 2018 13:09:21 #
Vince68 wrote:
Don't count on it ending anytime soon Steve.... its up to 8 pages now, and who knows how long this might go on.
Keep it going although it's not going to go anywhere.
Aug 21, 2018 13:11:20 #
artBob wrote:
... I am amazed at how many people do not even try the experiment to see if it's true. As I said, I thought it might be, but the only way to actually know was to test it. I've done that three times now, including using the photos of the OP himself. The EVIDENCE has always DISPROVEN the statement.
As a teacher, I am saddened by the lack of critical thinking and reliance on selective authority shown here. THINK! TEST! it's sure better than personal attacks, which just show your weakness.
As a teacher, I am saddened by the lack of critical thinking and reliance on selective authority shown here. THINK! TEST! it's sure better than personal attacks, which just show your weakness.
You can test until the cows come home but if you can't see the results from what has already been shown here it can only be because you don't want to see it.
If you can't be honest with yourself, what't the point of testing.
Most of us have observed this phenomenon (perspective determined by camera-to-subject distance) for decades. We understand how it works from experience.
Experience is the ultimate test. The proof of the pudding is in the eating.
Aug 21, 2018 13:17:07 #
Are there any others that have gotten to the point where they don't give a rat's behind whether or not lens focal length affects perspective?
Aug 21, 2018 13:18:18 #
artBob wrote:
Your "some minor distortions" are clearl... (show quote)
Actually the distortions are caused by the elements in the individual lens, not by changes in perspective. These distortions are also lens dependent and will vary depending on the construction of each lens. So images taken with the sensor at the same distance from the subject at different focal lengths may not align perfectly due to distortion added by the lens. This is true even when a single zoom lens is used at different focal lengths since the extent of the lens caused distortion is distributed across the image in a non-linear manner. This is why Ligthroom and other applications have lens specific corrections built in. They correct the image to compensate for shortcomings of the lens, not shortcomings of the laws of physics.
You should really take a few steps back and rethink this whole thing.
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