Tutorials - general info
Panoramas 360° - how is it done...
Camera and lens:
You can create a panorama with any camera and any lens. It doesn't matter what we use for panoramas, the technique is important. The shorter, the wider-angled lens we use, the fewer pictures we will need. Or, in other words, the more pictures we use, the greater resolution we will have. What do I have in mind: The world around us is 360° x 180°, if we take a wide lens, for example 15mm fisheye, we will have to take, let's say 8 pictures for the whole 360° x 180° to be photographed. We can also have an extreme lens fisheye, which creates a circle on the film and sees the full 180° x 180° - then 2 pictures will be enough. If we take a 50mm lens, then we will need more than 8 of these pictures, which is a result of its visual angle. The picture of winter from the link:
HRI was taken from 27 pictures with a 50mm lens and covers a visual angle of just about 100° - how many would you need to create a full 360° x 180°. But having many pictures, we will also have many pixels, and this results in increasing resolution. Can we use a cheap semi-fisheye converter of a conversion rate of 0,42x? Sure, but since it's not a real fisheye type of lens - it doesn't see full 180° - so we need more pictures. What to use? I can't answer this question. Or I will but not straightforward - anything. It's better to take pictures with anything than not take them at all, and along with experience, you will reach awareness, which will let you choose what is best for us. What do others use? Mainly nikon converters:
FC-E8 or FC-E9, or 8mm
sigma, lens, some use older or no longer produced
nikons 8mm f2,8, or
Zenitar 15mm or
Peleng 8mm, certainly cheaper than nikons. Others use
Raynox 185pro or 180pro and still others - anything. As you can see, the camera doesn't really matter and the lens. Extreme wide-angled lenses are mainly chosen, the best are the ones, which can see 180°x180° , because such lenses require the least pictures. The full-screen panoramas presented by me have been decreased to just 3500-4000px, even a nikon FC-E8 with the use of 2 pictures will give a higher resolution on a 7mln px camera. What becomes important is the quality of pixels... and this, unfortunately, can't be guaranteed by a FC-E8. I use a Cannon 350D camera with a 8mm lens or a raynox 185 pro.
Here you can find a set of images from sigma 8mm.
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Sigma 8mm, I usually also take a picture of the floor, but in The Royal Castle the conditions were quite hard and I didn't do it. |
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Raynox 185Pro exposes a full circle with a visual angle of 180°x180° on the 22mm lens. |
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And here we have a different technique of creating panoramas. Panoramas from kites. I take one picture of the earth from the air and then from the ground one picture of the sky - an IXUS 700 with a nikon converter FC-E8 flies. I stitch the picture in PTGui. |
Pano Head and tripod:
Apart from the camera, nothing else is necessary, but additional equipment will make work easier. The Pano Head is my name for the VR swivel (Virtual Reality). What is it? This is such a device, thanks to which we make a rotation with the camera around the correct axis. We have to use the PanoHead on a tripod, which gives us a certain stability and guarantees that the PanoHead is not displaced. Its existence is thus very obvious. Let's concentrate on the PanoHead. To be able to create a series of pictures we have to rotate the camera and shifts are connected with rotation. It is very difficult to take a series of pictures from hand. It's not about holding the camera in one's hand but it's about rotating around a very specific axis. People have a tendency to turn on the heels and this unfortunately unables us to correctly take pictures for panoramas. My friend John Houghton, who was also my teacher when it comes to panoramas, has written a guide how to stitch a panorama - I invite you to look at his
page. To correctly take pictures, we have to rotate around an optical axis of the lens we use (
nodal punkt). I like to think of it somewhat differently - we have to eliminate the parallax. I will make it more clear in a human language. A person has 2 eyes. The left eye sees something different from the right eye and that's a fact. It sees something different because the eyes are spread apart by about 13 cm. Please close your left eye and then the right one and compare. They see similarly but not identically. Stand in front of some object, for example a tree, a wall edge or are you sitting in front of the monitor, please compare again what one eye sees and what the other one sees, but this time pay attention to what is behind the wall or the monitor - definitely something different. When creating a panorama we have to avoid this effect. The lens - is our left eye - and after completing the full rotation, it has to stay in the place of the left eye, if we shift it during the rotation - it will see something different!
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The presented pictures show exactly what I have been talking about. These are 2 pictures from the panorama. Parts of these pictures overlap. For a panorama to be created correctly, pictures, despite the rotation of the camera, have to show exactly the same in the part which overlaps. Underneath you can find the so called crops - extracts in a resolution of more or less 100% of the original image from both pictures presented on the left. I picked this picture on purpose because you can see the mistakes the best when you use objects which are of different distance from the camera - this time it's the column, behind which, at a distance of about 2 meters, is a wall. |
So the pano head has to eliminate shifts, which take place when rotating the camera. Forget the complicated names such as nodal punkt or parallax - and focus on the shift. Below, you can see a diagram of what I have in mind.
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Correct rotation axis
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Wrong rotation axis
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Please carry out the following experiment: set up the tripod, put your hand at the end of the tripod and place the end of the lens on one of the knuckles, look into the camera, remember the image and lightly turn the camera around the axis on the knuckle where the lens with the camera is. You can more or less see the same. You can of course take test pictures and compare them. That's how it is - the best place to rotate the camera is somewhere at the end of the lens. I can't advise you what to buy, but I can tell you what others use. A piece of a metal plate - usually bent to make the letter L. Of course there are many people, who use great, expensive and heavy equipment, from which you can get a hump on your back. What do I use? A piece of metal plate...what it's made of - steel, stainless steel or aluminum, that depends on you.
Software:
There are very many programs, which can stitch a panorama, if you dig in the net, you will come up with a few dozen of them. For me there is only one - Panorama Tools. Panorama Tools is quite a difficult program and I must admit that I had a few problems with using it without any help myself. That's why programs which are a kind of interface for Panorama Tools, so called gui, thanks to which you can use it in a pleasant and simple way, have been created. I use PTGui. But there are a few other programs free of charge, which you can use - click on the links on the tutorial site. Pano Tools along with
PTGui. can correct practically any lens - and this is their basic advantage. Maybe they are not simple panoramas, on the contrary, they are quite time-consuming and they require certain knowledge but there is nothing that can replace them. With Pano Tools you can use IXUS 700 or Sony P200, Cannon 20D or Nikon D2x, with real lenses or converters - as long as there are no shifts.
Final advice:
That about wraps it up, I only have a few last hints. Pictures in a series have to be exposed exactly in the same conditions. I set the camera and the lens on manual. The sharpness of the lens, as well as the lens stop and the time of exposure, must be the same. It is also good to pay attention to the sun and see if it doesn't set while taking a series of pictures, as it might be quite funny when one take is very dark and there is no more sunlight on it. Panoramic pictures - are the only pictures, which require great dynamics because we have to take pictures with the sunlight as well as against it - so it is worth to pay attention to this detail - raw format, despite the fact that it's heavy, may turn out to be helpful.
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We have an example here of something called contrast blending. It's quite simple to explain but it's not simple to do. I once heard opinions that digital cameras create flat images in relation to old-fashioned films. I didn't understand this for a long time. The thing is in the details... Digital cameras see the screen in a certain area. When the picture dynamics is equaled out - everything is great, it gets worse when we have a large screen area. In such a case, the camera takes picture 1 or picture 2 - and there is nothing you can do about it, but when we connect both images - we have full dynamics, which our eye can see. It is something worth paying attention to. |
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HDR
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Here is the panorama: |
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HDR -
high dynamic range
Every lens has its faults, and digital photography makes them more visible. It is thus worth to first test the lens. A panorama is not just pictures in a series and linear layout of pictures - a panorama is also very correct photography. The sky is never green and it is also almost never white, and shades are not black but actually dark - try to get these details from pictures, treat the panorama as a masterpiece and not a "picture once". Each lens more or less suffers from chromatic aberration (also called
purple fringing). Try to eliminate the purple fringing before stitching a panorama.
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Here are two pictures, both have been created from the same file. But picture 1 has not been CA corrected (chromatic aberration). Picture 2 - yes. You judge the difference between them. |
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A quite important aspect is also vignetting - it is responsible for vertical darkening on the sky in the stitched panorama. I sometimes save myself with a picture of the sky or the ground if vignetting is too large - it is worth to even take the pictures from hand because we never know when we will need them.
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Almost nothing, but then again something, picture 1 doesn't have an improved vignetting, and picture 2 does. Believe me, the small detail has a great influence on the quality of connections. But as I have written, lenses, even the most expensive ones are not perfect, and we have to learn to live with them and go around these imperfections. |
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Here is the panorama: |
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The images presented are screen projections from PTGui.
Don't stint pictures! Panoramas are not just lines! There is a tendency to decrease the number of pictures in a series in the world, producers are racing in ideas to make fewer pictures, but as I have written, a panorama is not just lines - it is also the quality of connections, and the fault of the lens, doesn't explain our sloppiness or laziness. Of course you mustn't exaggerate with the quantity. Simply - the number of images must be dictated by the equipment, which we use and the conditions in which we take pictures.
Now you have enough knowledge to start acting on your own. I wish you good luck!
dakar
Konrad
