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Jun 12, 2007, 05:40 PM
HeliAP'er!
Hogster's Avatar
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Build Log

Slightly OT: Home-built tripod-mounted spherical-panorama head


Hi all

As you've probably noticed, recently I've been getting rather excited with the concept of spherical panoramas, albeit ones taken from the ground. Naturally I would love to be able to produce these from the air, but first things first eh

When I first started experimenting with these panoramas I was just using a simple tripod with a ball-head - not ideal for creating panoramas. To create a perfectly accurate panorama (which is particularly difficult inside when objects are much closer to the camera), one needs to rotate the camera about a point in its lens system known as the 'entrance pupil' of the camera. If you like, this is the infinitely small point in space where your spherical panorama 'appears to be taken from'. The simplest solution to ensure the camera is always rotated/moved in this manner is to buy a commercially-available panorama-head like the Nodal Ninja 3:

http://www.nodalninja.com/

This has been custom-designed to allow a wide range of cameras to be held with their respective 'entrance pupils' at the centre of rotation of the camera body. However, that particular baby comes in at 193 .... and with my rapidly-emptying bank account I reluctantly had to forget about buying one .... instead, I set myself the challenge of building one from scratch!

As many of you will know, I always start my projects with drawings, either computer-aided or hand-drawn. Having read through the instruction manual of the Nodal Ninja 3 (which is available from their website) and having grasped the principles behind finding the 'entrance pupil' of a camera, and seeing how the NN3 allows the camera to be rotated about this point, I started sketching some ideas:



These were the first things that came to my mind, and include several import aspects like key dimensions of parts of the camera. The black dot in the sketch at the top right is the location of the 'entrance pupil' of my camera, which I found by trial and error. The idea I settled on can be seen in the circle at the bottom left. Here is an enlargement (ignore the word tripod ):




With these things in mind, I drew a computerised version:



This isn't my initial drawing - it was modified slightly as I went along.


The first thing I tackled was the tightening knobs (of which 2 were needed). My thoughts were:

Buy them
Nick them from an old piece of equipment that wasn't used any more (an idea which was later discarded as I couldn't find any of the aforementioned pieces of equipment )
Make them from a cylinder of wood (and hope that one is be able to grip them well enough to do them up tight)
Mould them from scratch


My Dad and I have perfected a very clever technique for making more or less identical copies of things such as knobs using car-body-filler and a special plastic that melts in hot water but cools to become very strong and durable. The plastic is called Polymorph and for the car-body-filler we use Isopon P38 Filler which dries quickly and is very easy to sand.

Having found a nice-looking knob on our belt-sander in the garage ...



... I heated up a golf-ball sized amount of Polymorph (it comes as little pellets) and pushed the knob into it, making sure the plastic formed accurately around all the curves of the knob. The knob was then removed from the plastic, and the plastic was left to cool (with the aid of a cup of cold water). You can see the empty mould in the top left of the next photo. I then prepared the P38 (the red stuff you see on the spatula is the hardener):




The P38 (now mixed) was then spooned into the mould and the head of an M6 bolt was pushed into and under the surface of the P38. Here the P38 has already set and I had started to clear away some of the excess P38 from around the edge of the mould using a file.




By squeezing the mould in a vice, the P38 is released from the sides of the mould ...




... and our cloned knob can then be removed




A good deal of sanding and scraping (with a small steel ruler ... has a sharp edge that shaves layers off the P38 very nicely ) later and here's the knob ready to be painted:




Two layers of primer spray paint and two layers of gloss black spray paint (and a second moulding session ) later:




And how about that
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Jun 12, 2007, 05:41 PM
HeliAP'er!
Hogster's Avatar
Thread OP
With the knobs done I moved on to cutting out the wooden parts for the panorama head. Everything wooden is made from 11.5mm (odd thickness isn't it ) plywood, 30mm across. Lots of cutting and sanding later:



The more observant amongst you may have seen that on the smallest piece of wood (in the top left of that photo), there is a hole that has been filled in (with P38). Originally, I planned to use another knob (and hence I made 3 in total!) to hold that piece of wood against the longer piece .... however, that knob would have hit up against the longer piece, so I decided to just glue the small piece of wood in place and forget about the knob ... hence the hole which isn't being used anymore. The bolt for the tripod-mounting hole on the camera was set into the small piece of wood, glued in place with thin CA and then covered with P38. The small piece of wood was glued to the larger piece with more thin CA. Oh, and if you were wondering, that small piece of wood is needed to ensure that the main rotating arm of the panorama head lies centrally underneath the camera's lens - otherwise you will not be rotating the camera about it's 'entrance pupil'.

Several coats of primer and satin-black spray paint later, and the panorama head is complete!




Some more photos








And now with my A620 installed (with its massive wide-angle converter!):








I literally only completed this head this evening so I haven't had a chance to test it fully yet. However, initial fiddling has shown that it is a pleasure to use The action of rotating the camera in the horizontal and vertical planes is very simple and smooth, and the tightening knobs do their job very well. I will make a video to show me using the panorama head soon

Hope you enjoyed reading this thread as much as I enjoyed a) writing it and b) building the panorama head itself!

Until my next build,

Cheers,


David

PS. Oh and the only thing I had to buy was the spirit level ... which cost me 0.98 ... making this panorama head 1/196th the cost of the Nodal Ninja 3
Jun 12, 2007, 06:14 PM
Registered User
quailbird's Avatar
That is very professional looking! My hat is off to you! I'm sure what ever you make for the air will be just as good.
Jun 12, 2007, 06:23 PM
HeliAP'er!
Hogster's Avatar
Thread OP
Thanks quail!

I forgot to mention two things:

1) The knobs actually screw directly into the wood .... using an M6 tap, I tapped a thread into a small hole I had drilled in the plywood. Once I had removed the tap, I then poured thin CA down the hole, which solidified and effectively made a plastic thread inside the plywood. It's a technique I've used successfully many times in many different circumstances ... and I reckon you'd get blisters on your fingertips before you stripped the thread in that plywood

2) Although I have compared this to the Nodal Ninja 3, it's worth pointing out that my version is only compatible with my camera and with my lens. If I wanted to use another camera, the head would have to be completely redesigned, as many dimensions would need to be changed. But as my only camera will be my A620 for the near future, the inflexibility of my version didn't really bother me ... especially with its minute price tag


David
Last edited by Hogster; Jun 12, 2007 at 06:28 PM.
Jun 12, 2007, 07:40 PM
HeliAP'er!
Hogster's Avatar
Thread OP
Ok I've finished my first pano using this new tripod head and OH MY WORD ..... it's an absolute DREAM to use!! Another 29 photo pano inside our cluttered garage, and I can't find a SINGLE occurrence of a stitching error! PTGui must have thought it was in heaven!

So here it is, a spherical panorama of our garage .... and I'm soo unbelievably happy with it (and with the equipment I used to take it) that I could shout YAHHHOOOOOO at the top of my voice right now .... but have to restrain myself as the rest of my family is asleep

Garage Panorama

Man this is satisfying stuff


David (an ecstatic one!)
Jun 12, 2007, 09:32 PM
Registered User
Griffo's Avatar
Very impressive David! That garage is a hobbiests delight! The Pano is very clear and I love the logo on the bench below.

What's the total weight of your camera and lens convertor?

Did it take you long to stitch those photos together?
Jun 12, 2007, 11:13 PM
Not THAT Ira
Real Ira's Avatar
David,

As you know I've always been VERY impressed with the quality of your work and my opinions have just doubled.

Ira
Jun 13, 2007, 03:36 AM
Flying Kiwi
MisterNiceGuy's Avatar
We could play spot the 4 spare kettles in that picture. Well done, well designed and I am certainly looking forward to some outdoor shots!!
MNG
Jun 13, 2007, 05:15 AM
HeliAP'er!
Hogster's Avatar
Thread OP
Thanks guys

Griffo - the pano head weighs 147g (haha, compare that to 475g for the Nodal Ninja 3!!!! ) and the total weight including the camera (and monsterous wide-angle lens ) is 814g. It took about 10 minutes to take the photos (as I had to make sure I wasn't in each of the photos ), and maybe 20 minutes total for PTGui to stitch them, to P.shop over the tripod at the bottom of the panorama, add my logo and convert it to a QTVR. So maybe 30 mins total.

MNG - What a brilliant idea!


David
Jun 13, 2007, 08:32 AM
It flew...nearly!
Whoa! Blown away! How come everything is so evenly lighted, I would have thought there would have been a lot of shadows with all that stuff in there. I am betting your mother is never in that garage....

I think you need to offer your services to real estate agents, imagine panos and aerial shots for those upmarket flats and houses. You could offer the whole package in one go!

Cheers,
matthew
Jun 13, 2007, 12:14 PM
HeliAP'er!
Hogster's Avatar
Thread OP
The even lighting probably has quite a lot to owe to the magic of PTGui .... all the photos were taken at the same shutter speed, but PTGui 'colour corrects' each image to make sure the pano is evenly lit and coloured (I think I could see the white balance changing between photos ... and yet there's no evidence of that in the finished panorama ). It's quite incredible what the software can do!

You've hit the nail on the head with your 'whole package' suggestion Virtual tours inside and out, low-level shots from the mast/heli, high-level shots from the heli .... irresistable I would say


David
Jun 13, 2007, 12:31 PM
It flew...nearly!
Yepp, would think there is some moolah to be made there. Nipped over to the Ptgui site and holy moly! there are some nice panos there! Can well understand that you could get hooked. Wonder what results my little nikon 7900 would be capable of... Hmmmm, I need more money And your video David, to see how it works!
matthew
Jun 13, 2007, 01:21 PM
blundering through
Damn hogster,

that's top notch! well done.
Jun 13, 2007, 02:09 PM
Registered User
David I am well impressed, not just with the pano but also with the build, well done.

Ian
Jun 13, 2007, 02:16 PM
Professor of Wood
kd7ost's Avatar
Simply incredible David,

I have the utmost in respect for your attention to detail and what you build. Great show.

How did you keep that bolt 90 degrees true in the mold? Just good eyeballs?

Dan


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