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04-19-2014, 03:34 PM   #31
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QuoteOriginally posted by ChristianRock Quote
The main reason that I *want* FF is for distance perspective. Which I assume is the reason why landscape photogs use large format. I'll give an example… the other day I took a picture of my son in a big wooden train. I used my 35mm 2.4 which is my "normal" lens. It included everything I wanted in the picture, but the vagons behind the engine looked a bit smaller than the engine itself. If I took my eye off the viewfinder and looked to the scene, the train looked a certain way. Looking through the viewfinder, the background looked more distant and the wagons looked smaller. A proper "normal" lens is supposed to let you see the scene the same way the natural eye sees it. I'd need a "short telephoto" (50mm) range on APS-C for that, but then I wouldn't be able to include as much of the scene as I'd like.
I notice this in a lot of backgrounds when using my "plastic fantastic" as my walk around lens. It bothers me but not so much that I feel I *need* the change. It would just be a nice to have.
Will this "focal length changes perspective" myth never die? Perspective is not affected by focal length, or lenses, or cameras. Perspective is controlled by distance and orientation to subject/background only.

Object A and B are the same size. Object A is at 10 feet, object B is at 20 feet. Object A looks twice as big as object B (20/10). Move back 10 feet and A at 20 feet now only looks 1.5x bigger than B at 30 feet (30/20). You don't notice this effect because you have a fixed AOV with your eyes, and you are used to seeing things far away as taking up a small part of your vision. When you use a longer focal length to magnify a small part of your FOV, it will look unnatural, hence the "compression" illusion. In reality everything about that part of your FOV is the same as before, just viewed bigger now. If there is ever a difference in relative sizes/positions of objects between shots of different focal lengths, it is because you moved the camera (or distortion, which is a lens flaw, not a property of focal length).

Try it yourself. Take any two shots with any two rectilinear lenses of different focal lengths pointed at the same targets from the same spot. Crop the shorter one to match the FOV of the longer shot. There is no difference in perspective, which you will see very clearly once you match the angle of view, no matter how you got to that AOV, by cropping, zooming or both.

See the second page of this thread where this is discussed extensively, and I provide proof with photos doing this exact experiment I describe: https://www.pentaxforums.com/forums/169-pentax-full-frame/257907-just-simple-ff-2.html

Also, before anyone brings it up, the stretching you observe at edges of wide angle shots is not a matter of perspective, but a geometric property of rectilinear (gnomonic) projection, trying to get a spherical field of view onto a flat plane (the sensor/film) while keeping straight things straight. It is tied to angle of view, not focal length, and will look the same on any shot of the same angle of view barring distortion. Crop these edges out and you will see that nothing about the center has changed.


Last edited by Cannikin; 04-19-2014 at 05:08 PM.
04-19-2014, 05:52 PM   #32
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I don't NEED ff, but it sure is easier on my wallet.
04-19-2014, 08:31 PM   #33
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I have been coming to the conclusion that a sensor fitted with the right lens for the right job will produce the right image. MF, FF, APS, u4/3, etc I won't trip over my own feet anymore to get a FF but I'll dance any jig to any tune for the right lens!

The biggest draw for me to FF would be a big, bright , beautiful OVF.
04-19-2014, 08:35 PM - 1 Like   #34
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QuoteOriginally posted by ChristianRock Quote
35mm lenses will distort, regardless of the size of the sensor that they throw light on... same with other focal lenses - they have their optical characteristics and that is that. I know that stepping back would reduce the problem, but it doesn't get rid of it. Otherwise, I could use a wide angle lens and step 500 feet back and it would approximate the background behind my subject... no it won't do that. But a long telephoto approximates the background.

Also, stepping back sometimes isn't an option anyway.

Who am I going to believe, you or my lying eyes... lol
Did you even try what I said? Did you even look at the photos I pointed you to? It would take less than 30 seconds to look at them, a lot less than it took you to post this. Here, since you can't be bothered to click on a link, I will post them again for you:

70mm:


70mm cropped:


130mm:


I didn't move the camera between shots. Tell me, what has changed about the perspective even after I almost doubled the focal length (ignore the slight exposure difference)?

EDIT: See two posts down for an even more extreme 10mm vs 50mm example.

Would you also "trust your eyes" which tell you the Earth is flat, or that the Sun moves around the Earth? Because they sure seem like it at first glance. Yet these are illusions that are false, just like "focal length changes perspective" is an illusion that is false. The geometry of perspective has been well established for thousands of years since Euclid. So-called "perspective distortion" seems unnatural because human eyes/brains, with their fixed AOV, are not used to viewing things like that. If you want more reading material, you can start by reading the third paragraph in the introduction section of this article: http://en.wikipedia.org/wiki/Perspective_distortion_%28photography%29


Last edited by Cannikin; 04-20-2014 at 03:52 AM.
04-19-2014, 08:42 PM   #35
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QuoteOriginally posted by Cannikin Quote
Did you even try what I said? Did you even look at the photos I pointed you to? It would take less than 30 seconds to look at them, a lot less than it took to you to post this. Here, since you can't be bothered to click on a link, I will post them again for you:

70mm:


70mm cropped:


130mm:


I didn't move the camera between shots. Tell me what has changed about the perspective even after I almost doubled the focal length (ignore the exposure difference)? If you want you can even post your own photos. Take them from the same spot, pointed at the same targets, with any two focal lengths you want, and I will crop them for you and prove you wrong with your own photos.

Do you also "trust your eyes" which tell you the Earth is flat, or that the Sun moves around the Earth? These things are 100% false, just like "focal length changes perspective" is 100% false. Geometry is geometry as has been well established for thousands of years.
Myths and psuedoscience float around this forum like a plague. And if you keep arguing science against these "nonbelievers," a moderator will ban you from the thread without warning.
04-19-2014, 09:39 PM   #36
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QuoteOriginally posted by ChristianRock Quote
...
Here's an even more extreme example, a whopping 5x crop from a 10mm to the FOV of a 50mm, going from ultrawide to short telephoto without moving the camera (K-3):

10mm:


10mm cropped:


50mm:


So tell me, what is the difference in perspective that you claim focal length affects? All I see is that everything in the 10mm crop has the same relative size and position as in the 50mm shot because both were in the same spot pointed in the same direction. Ignore the DOF, that's obviously going to be different.

For reference, this Balrog figurine is 10 inches tall and 7 inches deep (roughly the size of a human head if you want to extrapolate). Shot from approximately 3 feet in front of it (the 70 vs 130mm was shot from about 9 feet away). The dragon is 18 inches behind it, and the bookshelf is approximately 6 feet behind it.

The original files for this, and the above 70 vs 130mm shots, are available for download if you want to try it yourself. Just don't look too closely at my apartment, please.

EDIT: changed the 10mm vs 50mm photos to a clearer demonstration.

Last edited by Cannikin; 04-20-2014 at 01:27 AM.
04-20-2014, 08:01 AM   #37
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Your thoughts on using a 35mm and getting distortion-- a FF camera with a 50mm lens, at the same place, will look pretty much identical. Angle of View is Angle of View, whether micro 4/3 or 4x5 film.

However, with flange-focal distance figures, a 35mm lens requires more correction to have the correct F-F distance, and there's more chance to have distortion inherent vs. a longer lens. Maybe try a better 35mm lens?

Also, 35 on APS-C/50mm on FF is too short for any kind of tight portrait work. It's not lens distortion that affects that, it's the fact that you have to be too close, making things like noses look big.
04-20-2014, 08:04 AM   #38
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QuoteOriginally posted by ironlionzion Quote
Myths and psuedoscience float around this forum like a plague. And if you keep arguing science against these "nonbelievers," a moderator will ban you from the thread without warning.
I thought *I* was the only one.

You just have to be three steps nicer than the people that are insulting you.

04-20-2014, 12:04 PM   #39
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QuoteOriginally posted by ironlionzion Quote
And if you keep arguing science against these "nonbelievers," a moderator will ban you from the thread without warning.
Only when posts violate forum rules.

BTW, just a heads up/warning, forum rules specifically prohibit open discussion of moderator actions. If you wish to discuss an issue, please use the Contact a Moderator feature.

Last edited by Parallax; 04-20-2014 at 02:15 PM.
04-20-2014, 12:16 PM   #40
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You just have to know how to work with your gear. The FA 31 limited takes great portraits, just not head and shoulders types. The problem is when you use a super wide angle (or even a moderate wide angle) to get really, really close to your subject. Obviously they are going to look odd, whether you are shooting on a crop or full frame camera.

(FA 31 limited shot)



Last edited by Rondec; 04-20-2014 at 12:45 PM.
04-20-2014, 12:26 PM   #41
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QuoteOriginally posted by Rondec Quote
You just have to know how to work with your gear. The FA 31 limited takes great portraits, just not head and shoulders types. The problem is when you use a super wide angle (or even a moderate wide angle) to get really, really close to your subject. Obviously they are going to look odd, whether you are shooting on a crop or full frame camera.

(FA 31 limited shot)


Your statement of ...and I quote...." You just have to know how to work with your gear. " hits the nail on the proverbial head.

I'm not pointing fingers, but as a general comment, too often I feel that photographers look at their final product and blame the tools at hand.

Some of us are pretty good at rationalizing why we need different equipment (myself included)...when perhaps what we do 'need' is more practice to develop the expertise to use the full potential of the equipment we do have.

Case in point. I recently looked at an 11 X 14 of a frog, lily pad scene that a friend had taken. She used her Pentax KR and 55-300 Pentax consumer lens. It is a fabulous picture and even at that enlargement was sharp as a tack.

Yes the lighting (available...natural) was perfect....but her technique, equipment setting choices and eye for composition...triumphed.

Honestly I do not believe her photograph could of been better with say a 5D2 or 5D3. She knows what she's doing, knows how to work the equipment she has to it's maximum and understands lighting.
04-20-2014, 01:28 PM   #42
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QuoteOriginally posted by Rondec Quote
You just have to know how to work with your gear. The FA 31 limited takes great portraits, just not head and shoulders types. The problem is when you use a super wide angle (or even a moderate wide angle) to get really, really close to your subject. Obviously they are going to look odd, whether you are shooting on a crop or full frame camera.
I specifically love using it for head/shoulder shots. Yes, there is certain 'marginal' degree of distortion (i mean its like 47mm after all) but the way it renders up close completely makes up for it...
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04-20-2014, 02:10 PM   #43
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Nice lighting!!
04-20-2014, 02:17 PM   #44
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QuoteOriginally posted by oxidized Quote
I specifically love using it for head/shoulder shots. Yes, there is certain 'marginal' degree of distortion (i mean its like 47mm after all) but the way it renders up close completely makes up for it...
Ya, but if I'd taken those images with my 70....
04-20-2014, 02:55 PM - 1 Like   #45
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QuoteOriginally posted by normhead Quote
Ya, but if I'd taken those images with my 70....
....with my 70 ..... i wouldnt have been so close to the subject besides this is what I really love about the 31. The bokeh is soo buttery smooth but the background objects are visible. I feel like 70mm+ just blurs too much and all you are left is with some face isolated out of a background. With the 31 you actually have the atmosphere of the setting. You can see where the subject is. There is a lot more going on in the photo.

EDIT: here is another example. Even when you step further back the separation is still there, but do you REALLY need more blur? Is it going to help the photo? I dont know...
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Last edited by oxidized; 04-20-2014 at 03:01 PM.
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