Balliolman
8th of April 2009 (Wed), 05:59
Introduction
Freeviewing is a skill which can be mastered by anyone with binocular vision including corrected vision through the use of contact lenses, spectacles or a monocle. Because it is a skill, freeviewing takes time, patience and practise to acquire. If you are sighted in one eye only, I am sorry to say you cannot perceive depth, as you undoubtedly know already.
There are two forms of freeviewing; that required for parallel stereos and that required for crossed stereos. Typically the stereos posted to this forum so far have been crossed pairs. The following technique applies to crossed stereos in which two similar photos are presented side by side. Please understand if you are looking at a single image which appears red and blue and a bit fuzzy then you are looking at an anaglyph. Anaglyphs require viewing aids, typically spectacles with one red lens and one blue/cyan lens.
A stereo image is so presented to allow the viewer to perceive depth, hence the third dimension. In parallel stereos the left image represents the scene as perceived by the left eye and the right image as seen by the right eye. In crossed stereos the photos are switched over, hence the need to cross eyes to perceive depth.
What's so good about crossed freeviewing?
Crossed freeviewing allows stereos from tiny to very large indeed to be viewed comfortably and instantly without the need for viewing aids. (Parallel stereos which are broader than the natural distance between pupils require viewing aids.)
Okay, enough with the theory, so how do I freeview ...
Simply try this to develop freeviewing skill: sit 2-3 feet from your monitor. Cross eyes slightly. The left eye looks at the right image and the right eye looks at the left image. Do not strain or go bug-eyed. Relax. A central image giving stereo depth will appear. http://www.inspiring-photography.com/forum/images/smilies/icon_biggrin.gif
But I have done this lots of times and nothing happens as it should
Typically learner freeviewers make comments like, "I tried but:-
everything went fuzzy and moved about,
I saw four images
I got headache/eyestrain/pain
I saw something briefly but lost it.
The first three are caused by either or both of the following conditions crossing eyes too vigourously or attempting to view a badly aligned stereo. A really badly aligned stereo cannot be viewed by anyone: period! Eyestrain can be avoided by crossing eyes minimally. In crossing eyes a viewer is using their eye muscles in a particular way, like any muscle action first attempted persistently, the muscles will fatigue easily but with practice they become accustomed to such usage. With practice crossed freeviewing can be done comfortably for a very long time.
Keep your head steady. When depth is perceived a viewer can roam about the scene without head movements.
Often when first getting a stereo to 'pop' excitement makes a viewer lose concentration! http://www.inspiring-photography.com/forum/images/smilies/icon_smile.gif
Alright then, so how much do I need to cross eyes?
The closer your eyes are to a subject then greater is the need to cross eyes and vice-versa. So the trick is to discover your optimum viewing distance from your monitor. Experiment go a little closer or further away. I recommend being further away as a start. Remember, the further away the less need to cross eyes.
A comfortable viewing distance is also dictated by the size of the image being freeviewed. The larger the image then greater the viewing distance required. It is possible to freeview images measured in metres if the viewpoint is far enough away. http://www.inspiring-photography.com/forum/images/smilies/icon_eek.gif
Last tips
Eyestrain is nature's obvious way of indicating a viewer is trying too hard. Practise little and often is best. Some people can freeview effortlessly and immediately at their first attempt: lucky them. Many people have to keep at it for a while (it took me a couple of days to get the knack). Also some stereos are easier to view than others and this varies between individuals. Suffice to say, practise will lead to success!
Some people when depth is perceived like to bring their palms across their field of vision to blinker off the far left and right images so only the central image is viewed. I quite liked doing that at first but now dont bother as freeviewing has become utterly effortless.
Yay, I can now freeview! Now what?
Congratulations! I hope you will now enjoy many hours of freeviewing stereo photography.
Tell us all of your success by replying to this thread so we know you have joined the stereo fraternity!!
__________________
Balliolman
Stereoshooter
Freeviewing is a skill which can be mastered by anyone with binocular vision including corrected vision through the use of contact lenses, spectacles or a monocle. Because it is a skill, freeviewing takes time, patience and practise to acquire. If you are sighted in one eye only, I am sorry to say you cannot perceive depth, as you undoubtedly know already.
There are two forms of freeviewing; that required for parallel stereos and that required for crossed stereos. Typically the stereos posted to this forum so far have been crossed pairs. The following technique applies to crossed stereos in which two similar photos are presented side by side. Please understand if you are looking at a single image which appears red and blue and a bit fuzzy then you are looking at an anaglyph. Anaglyphs require viewing aids, typically spectacles with one red lens and one blue/cyan lens.
A stereo image is so presented to allow the viewer to perceive depth, hence the third dimension. In parallel stereos the left image represents the scene as perceived by the left eye and the right image as seen by the right eye. In crossed stereos the photos are switched over, hence the need to cross eyes to perceive depth.
What's so good about crossed freeviewing?
Crossed freeviewing allows stereos from tiny to very large indeed to be viewed comfortably and instantly without the need for viewing aids. (Parallel stereos which are broader than the natural distance between pupils require viewing aids.)
Okay, enough with the theory, so how do I freeview ...
Simply try this to develop freeviewing skill: sit 2-3 feet from your monitor. Cross eyes slightly. The left eye looks at the right image and the right eye looks at the left image. Do not strain or go bug-eyed. Relax. A central image giving stereo depth will appear. http://www.inspiring-photography.com/forum/images/smilies/icon_biggrin.gif
But I have done this lots of times and nothing happens as it should
Typically learner freeviewers make comments like, "I tried but:-
everything went fuzzy and moved about,
I saw four images
I got headache/eyestrain/pain
I saw something briefly but lost it.
The first three are caused by either or both of the following conditions crossing eyes too vigourously or attempting to view a badly aligned stereo. A really badly aligned stereo cannot be viewed by anyone: period! Eyestrain can be avoided by crossing eyes minimally. In crossing eyes a viewer is using their eye muscles in a particular way, like any muscle action first attempted persistently, the muscles will fatigue easily but with practice they become accustomed to such usage. With practice crossed freeviewing can be done comfortably for a very long time.
Keep your head steady. When depth is perceived a viewer can roam about the scene without head movements.
Often when first getting a stereo to 'pop' excitement makes a viewer lose concentration! http://www.inspiring-photography.com/forum/images/smilies/icon_smile.gif
Alright then, so how much do I need to cross eyes?
The closer your eyes are to a subject then greater is the need to cross eyes and vice-versa. So the trick is to discover your optimum viewing distance from your monitor. Experiment go a little closer or further away. I recommend being further away as a start. Remember, the further away the less need to cross eyes.
A comfortable viewing distance is also dictated by the size of the image being freeviewed. The larger the image then greater the viewing distance required. It is possible to freeview images measured in metres if the viewpoint is far enough away. http://www.inspiring-photography.com/forum/images/smilies/icon_eek.gif
Last tips
Eyestrain is nature's obvious way of indicating a viewer is trying too hard. Practise little and often is best. Some people can freeview effortlessly and immediately at their first attempt: lucky them. Many people have to keep at it for a while (it took me a couple of days to get the knack). Also some stereos are easier to view than others and this varies between individuals. Suffice to say, practise will lead to success!
Some people when depth is perceived like to bring their palms across their field of vision to blinker off the far left and right images so only the central image is viewed. I quite liked doing that at first but now dont bother as freeviewing has become utterly effortless.
Yay, I can now freeview! Now what?
Congratulations! I hope you will now enjoy many hours of freeviewing stereo photography.
Tell us all of your success by replying to this thread so we know you have joined the stereo fraternity!!
__________________
Balliolman
Stereoshooter