The Universal Compass & Bubble level Panorama Camera Bracket: Users Guide
The Universal Compass & Bubble level Panorama Camera Bracket: Users Guide
Theory of operation
Panorama Photography or photographs of a very wide field of view have been around for over a hundred years. Very special cameras which could expose a continuous strip of film, or a Sequence of narrower photographs were spliced or "stitched" together to form a single very wide image.
Now, with the extensive graphics capabilities of the current generation of home computers, several programs have been developed which can automate the process of aligning a set of individual standard size images into a single panoramic view. In addition to being able to print out these panoramas, a new application of actually being able to take an entire 360 degree sequence of photographs and stitching and wrapping them into a 360 degree virtual reality image which can be displayed on the computer screen or even on a website. A virtual viewing window can be steered to look at any part of the panoramic view, just like you were actually standing where the panorama was taken and looking around the landscape.
In order for the series of individual photographs to be able to be stitched together, they need to be taken so that they are all at the same height from one to the next, the camera must be level, and there must be a consistent overlap of one image to the next of about 20 to 50 percent of the image. Although it is possible to take a panorama sequence by hand, especially of a far off scene, it is difficult to keep everything lined up to get a good result especially with closer object or subjects.
One of the biggest problems with closer objects or with indoor scenes is "parallax error". You have probably seen parallax when looking out the side window of a moving vehicle. Closer objects seem to be moving much faster than far off objects. This kind of view change from one photo in a sequence to the next will cause it to be difficult to stitch the photos as it looks like some of the near objects have "jumped" to the left or right between the two photos.
To overcome this parallax error problem, the camera and its lens can be rotated around its "NODAL POINT" as the panorama sequence is shot. The nodal point is the fancy optics term for where the light entering the lens assembly comes to a focus point before continuing on and hitting the film or electronic sensor array in a digital camera. Usually this point is somewhere inside the lens or camera, but it could actually be in front of or even behind the camera. It is also at different points with different lenses with the same camera, or even at different zoom settings. We will discuss finding the nodal point in greater detail later.
Finally, for most panoramas it is desirable to have as much vertical height to the image as possible. Since we are stitching several shots together anyway, then turning the camera to its "portrait" mode with the longer dimensions of each photo vertical give us the largest vertical field of view for our panorama sequence.
To get a full set of photos for a 360 degree panorama set, you could need between 2 and 36 photographs for an entire sequence according to what lens is on the camera. The wider the lens view (the smaller the "mm" of the lens) the fewer photos needed. A typical camera at its widest zoom setting is about "35mm" or equivalent focal length of its lens, and would need 12 to 16 shots to make a full 360 set it the portrait mode.
So to sum all of this up, to get the best results for our panorama from our sequence of photos
:The camera must be held level through the entire sequence of shots.
The camera should be held "sideways" in the portrait mode to get the maximum vertical view.
The camera should be rotated around its "Nodal Point" to eliminate parallax errors.
The camera should be indexed or turned by an even amount between each shot with about a 30% overlap between photos.
You will need to take about 16 or more photos to get a full 360-degree coverage.
Although it may sound like standing on you head and gargling peanut butter may be easier, do not despair, the panorama bracket comes to the rescue.
There have been panorama camera brackets available for many years. Most either have millimeter scales and micro adjustments or are made for only a single model of camera. They usually have either degree scales or a mechanical system with détente disks to help space out each shot. They need to be mounted on an upscale tripod. They can give excellent results. They usually cost from several hundred to over a thousand dollars each and are targeted at professional photographers.
The Compass and Bubble Level Panorama Bracket
The Compass and Bubble Level Panorama Bracket is targeted at getting down to the basics of taking a panorama sequence of photos. Instead of built in micro adjusting scales and rulers or a single model camera design, the Compass and Bubble Level Panorama Bracket is based on the idea that once you configure and adjust for a particular camera and lens, you tighten the adjustment screws in place and it stays in that configuration. Instead of a mechanical détente stop with expensive wheels, you use a simple magnetic compass to get the sequence positions by aligning the compass needle with a set of stop lines on a printed sheet under the transparent bottom of the compass. (A mechanical click stop is available from Bogen/Manfrotto (#3414) on which the Panorama bracket can be mounted if you wish to upgrade at a later time). A "bubble" or spirit level is mounted on the bracket to check that everything is level while setting up and taking the sequence. The bracket has a wide range of adjustment so that it can be used with nearly any digital or film camera.
Configuring the Compass and Bubble Level Panorama Bracket for you camera & tripod/monopod.
Since there are so many variations of cameras, the Panorama bracket comes in a semi kit form to allow you to configure it specifically for your camera, lens and tripod or monopod.
The panorama bracket consist of
A- An extruded aluminum channel and end caps
B- An aluminum "L" bracket
C- A quality map type compass with special mounting holes
D- A set of ¼-20 "double T nuts" which slip into the channel hold the L bracket and to mount the tripod
E- A set of stainless steel (non-magnetic) t-nuts and stainless Phillips screws to mount the compass.
F- ¼-20 set screw
G- ¼-20 machine screws & washers to hold the "L" bracket
H- ¼-20 nylon thumbscrew to mount the camera to the bracket assembly
I- Self-adhesive foam strips, and self-adhesive anti-skid strips to keep the camera from rotating.
J- A spirit bubble type level.
K- A nylon retention washer
L- Double sided tape to mount the level and the washer
M- A set of hex wrenches to tighten adjustments. (You will only need to supply a small screwdriver.)
With the endcaps off the aluminum channel, notice that there are two slots on both the top and bottom of the extruded channel. Take one of the double ¼-20 t-nuts and put the setscrew in one of the two holes with the hex end of the setscrew on the flat side of the t-nut. Slide the t-nut into the bottom right slot with the open hole in the t-nut toward the front edge of the channel. Position the open hole about ½ of an inch from the front edge of the channel. Tighten the setscrew to keep the t-nut in place. (Note you may have to temporarily install a ¼-20 screw to center the open end of the t-nut to center it while you tighten the setscrew.) This open ¼-20 hole will be the receptacle for the ¼-20 screw on you tripod or monopod.
Put a ¼-20 button head screw through a washer and through each of the two slots on the "L" bracket, and start each screw into the flat side of the t-nut. Slide the t-nut into the end of the right top channel with the vertical part of the "L" bracket to the right of the extruded channel. Position the front edge of the "L" bracket about an inch from the front of the extruded channel.
Put a #10 stainless screw down through each of the holes in the map compass, and start them each into a #10 stainless t-nut. Slide the t-nuts into the top channels from the back edge of the extruded channel, and position the compass so it is over the channel. Snug the two compass screws so the compass stays in place. Note: Do Not over tighten these screws or you could crack the acrylic compass base.
Adjusting the Panorama bracket for you camera and lens:
With the camera and lens you are going to be using, chose on of the holes on the vertical part of the "L" bracket to mount you camera. Choose one not too high up, but one which will allow enough clearance between the camera and the two ¼-20 button head screws to use the hex wrench to adjust them without removing the camera if possible. Put one of the sets of self adhesive non-skid strips along side of you chosen mounting hole. Two types of strips are provided, a thin rubber type, and a "closed cell" foam type. The resilient foam easily deforms to "mold" itself around the base of the camera which helps keep it from turning, but resumes its original shape within a few minutes of taking the camera off. The thin rubber type may work better if you are going to use a quick release plate system. You may have to experiment to see which works best for you camera. Mount you camera to the "L" bracket using the ¼-20 nylon thumbscrew. The nylon retainer washer may be adhered to the outside of the "L" bracket with some of the double sided tape to help retain the nylon thumbscrew in place. This will not be needed if you are going to use a quick release plate system. (Please see the note below on plastic camera tripod threads and quick release mounts)
The objective of setting the bracket for your camera and lens is to position the camera so that the "Nodal Point" of the camera’s lens is directly above the mounting point for the tripod/monopod. (Which should be above the pivot of you tripod. See notes below for odd tripods.)
First, adjust the "L" bracket left or right until the camera lens is centered above the channel with the t-nut for the tripod is mounted, usually the right slot, the same one the t-nut which is holding the "L" bracket is in. (Note that on very tall cameras where the center of the lens is more that 2 inches from the base of the camera, the bottom t-nut may have to be moved to the left slot which allows another full inch of camera base to lens height.) Make sure the "L" bracket is setting square to the extruded base and snug the two ¼-20 screws holding the "L" bracket. You can check the left/right alignment by loosening the thumbscrew holding the camera and pointing the camera down at the bracket. The extruded channel slot should be exactly centered in the viewfinder, or with a digital camera, take a photo and check that the slot is exactly centered in the higher resolution image. You can mark a couple of small dots on the bottom of the "L" bracket to mark its correct left-right position relative to the extruded base.
Now loosen and reposition the camera facing forward. The camera must be pointing parallel with the extruded base. A quick way to check its position is to take drafters 90 degree drawing triangle or similar square and make sure the front of the lens is at exactly 90 degrees from the top surface of the extruded base. Put a couple of small dots on the non-skid surface at the edge of the camera base to make it easier to re-attach the camera anytime.
Noodling the Nodal Point.
Now we get to finalize the setting for the infamous nodal point. Mount the panorama bracket with the camera on you tripod.
We are going to find the nodal point by using the parallax error. Keeping the "L" bracket it its same relative left-right position we found in the last step, move the bracket to all the way forward. We now need to find two vertical edges, one within a couple of feet, and another fifty to several hundred feet away. The camera & lens should now be forward of its nodal point. Looking through the viewfinder of a SLR camera, or at the LCD screen of a digital camera move the tripod until the two vertical objects are exactly in line with each other and they appear near the left side of the image. Now rotate the tripod head using the pan the tripod to the left so that that the image of the two vertical objets moves to near the right of the viewfinder screen. They should seem to move apart from each other, and no longer be in line. This is the parallax error that can cause so many problems.
Now all we have to do is move the "L" bracket back a few millimeters at a time, and as we approach the nodal point, the near and far vertical lines will move less and less out of alignment with each other until we reach the nodal point at which they will stay in perfect alignment, no matter which way we pan the camera. If we pull the bracket back too far, and pass the nodal point, the two vertical surfaces will start moving out of alignment the other way. When we have found the nodal point, tighten the two screws holding the "L" bracket in place, and double check that the two vertical objects stayed in line and that nothing moved while everything was being tightened. You now have the Panorama bracket set for your camera and lens. It should be ready now any time by just putting your camera on the panorama bracket until you change cameras or lenses. Note that it is a good idea to check that nothing has moved from time to time by lining up a near and far vertical object and making sure there is no parallax error as you pan your camera from side to side. Again it is a good idea to make a couple of alignment dots on the extrusion to easily re-position the "L" bracket if it gets loose.
In these images, the ink pen point is aligned with the edge of the downspout on the house next door in the left image. The middle image shows the parallax error when we panned to the left. See how the ink pen seems to have "jumped" out of alignment with the edge of the downspout. After we have moved the "L" bracket to find the Nodal point, the image of the pen stay in alignment with the downspout edge when panned to the left or right of the viewfinder. Please note that the image in the viewfinder is relatively small, and after you are close you should take test photos which will be much higher resolution and let you check your alignment more closely.
How many Clicks does it take to get the full 360 panorama?
We can determine how many individual photographs we will need to stitch them into a 360-degree panorama. Line up any convenient vertical edge with the left edge of the viewfinder screen. On the compass, turn the bezel until the arrow printed on the bezel in aligned under the north (red) end of the compass needle. Now pan the bracket to the left just as when we were setting the nodal point, until the vertical object is about 1/3 of the screen width from the right edge of the viewfinder screen. Now we can read how many degrees we rotated the camera and bracket to leave a 33% overlap. If for example we moved approximately 26 degrees, then we take 360 divided by our 26 degrees is 13.8 photos for a full 360 degree panorama which we will round off to 14 photos per panorama set.
Take a pair of scissors and cut out the 14 stop compass guide (or whichever guide you need) from the compass guide sheet. Loosen the two screws holding down the compass, and slip the compass guide between the compass and the extruded base. Carefully line up the guide sheet under the transparent compass using the printed guidelines and inner and outer circle, it needs to be very well centered around the center of the compass needle. Carefully snug the two screws holding the compass, again without over tightening them. Double check the alignment and we are ready for the final step.
The bubble sprit level is attached using double sided tape. It is best if it can be attached directly in front of the camera, but according to how far back the "L" bracket had to be positioned there may not be enough room. In that case, it can be mounted on the "L" bracket itself or in front of the "L" bracket. When using the bracket with a monopod it is best if the spirit level and the compass are near each other as you have to keep watch on both of them for each shot. A smaller diameter spirit level is carried at Sears stores, and their Hardware mini stores for about $1.50 if a good location is not available for the larger bubble level provided.
Basic Instructions on Taking a Panorama Sequence.
Place monopod in what is to be center of panorama.
Point camera in general direction of what is to be first Photo in sequence.
Put one hand on the camera where you can depress the shutter release button.
Put the other hand on the monopod just under the photo bracket where you can guide and steady it.
Move camera bracket slightly to Line up RED end of compass needle over nearest sequence line. Rotate the compass bezel to align the bezel arrow marking with the red end of needle. This helps you remember you exact starting point.
Keeping red end of needle aligned, Level using the bubble level. When both level and pointing in proper direction, Gently depress the shutter release on the camera keeping the camera still so you do not blur you shot. (This sounds difficult, but it will become second nature with
practice and experience.)
Keeping the base of the monopod in place, Pan right until the Red end of the compass needle is over the next tick mark on the guide slip-sheet. You will probably be taking a half step around the monopod each pan to keep you body out of the shot, and where you hands need to be on the camera. Align, Level and squeeze for the photo shot. Continue around aligning the needle, leveling and shooting. When the needle is back over the Bezel arrow, you know you have completed the sequence. (Note you should only use one end (I recommend the red end) of the compass needle to line up the markings in case you use a stop sheet with an odd number of stops).
Some tips on taking Panorama sequences:
Concentrate on what you are doing as you are taking the sequences. It is easy to get out of sequence (take two shots or skip a shot) when you are taking 20 shots for a single sequence.
The following are other sites that have a lot more information on setting up for and taking panorama sequences.
My current photo products are at
http://easychairworkstation.com/P3products.htm .We reserve the right to make updates and modifications to the designs shown, and some items may vary somewhat from image shown. All measurements are approximate and may change with future design changes.
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