As promised, here a more in depth description of how to make the home made overhead projector, which will help immensely with the geography of your compositions and also save you lots of money.
Firstly, I will use this thread to describe the process in as much detail as I can, so there is no need to post replies here, however, if you see anything here that you think can be done easier or quicker, then feel free to post, all input is welcome, also if you have questions or something isn't clear, post your question here.
Note that I will use my own projector as an example, and will state all measurements and dimensions from there, but these are by no means compulsory, the measurements of your own will be dependant on the parts you use, this will become clear later in this thread.
Also note that the projector here was purposely made to project onto standard A2 paper at approximately 1.2 metres from the work surface, if you want to make a full size projector you will find that the Fresnel lens mentioned below will be difficult to find and also be very expensive, with this format you will stay comfortably under $40.
A list of all the things you will need and where necessary a description of their purpose
1. A photo frame 13.5cm X 18cm, you can make this yourself but they cost almost nothing, this will act as the bed for your transparencies.
2. A lamp, your light source, I recommend an led lamp like the one in the photo because they do not get hot, if you use any other type of lamp you will need to install a cooling fan and since some your parts are plastic this could be dangerous, the lamp in the photo is 10cm X 14cm app and you can find these at any D.I.Y. store, this will constitute the bulk of your cost, but because the lamp is loose it can be used as extra light source for your work, take note that these lamps are usually supplied without the power cable as this one was, if that is the case you will need that too.
3. A fresnel lens named after it's inventor, Augustin Fresnel a French physicist, this lens was first used in light houses, although you can see them all around your car, it simply distributes the light over the whole area of your transparencies, the one in the photo or similar is available at most book shops, because it is made as an aid to book reading for sight impaired people, the lens in the photo is 12cm X 18cm and will be detached from it's frame later.
4. A standard magnifying glass, used to magnify and project your image, the one in photo is 7.5 cm in diameter, you can use something a little larger, but preferably not smaller, you can find these also at book stores or hardware stores.
5. A mirror, all this does is project your image at 90 degrees form the horizontal, not absolutely necessary if you can draw on the ceiling or lie your projector on it's side. the mirror I used is 7.5 cm X 11 cm, a little bigger is no problem, but not smaller.
6. Aluminium L profile approximately 1 metre X 1cm, available at all D.I.Y. stores, this will provide you with a rail for your projector head and allow you to focus your image at different distances.
7. Some 3mm plywood to make the box/casing, about 0.5 square metres should be sufficient, to bring your box together some wood triangle profile is also handy, my box is 21cm high, 18cm wide and 13.5cm deep.
In the next post, I will proceed further with the build process, this will give you time to pop out now and get all the parts, .
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