Floppy Disk Sun Filter

Several months ago I posted an Instructable about making a simple sun filter with a black marker and a sheet protector. That approach, although it did block out most of the light, didn't work very well and threw everything out of focus. This one, using a floppy disk and some card stock, works much better and doesn't take anywhere near as long to make. There's also slightly less of a pink color, though part of the blue component of the color seems to be from UV that makes it through the filter. The effect seems to go away when used with a telescope for some reason. Instead, the disk filters the light to a more realistic orange.

Step 1: Supplies

You'll need a camera with optical zoom (this is important, you'll be using the lens barrel to keep the filter attached) a floppy disk, some thick paper, glue, scissors, and tape might be helpful in assembling the mount.
I'm also using an old computer as a surface. You can use any old computer you  might have laying around, or you can just use a normal table.

Comments

[georgeATM]

Please note that using homemade filters should only be used for photography and not visual observing. Solar observing is the only activity in astronomy that is inherently dangerous. Using any filter that is not specifically designed for this activity can be dangerous because there are wavelengths of light that the human eye can't see but are still harmful to the structures of the eye, specifically ultraviolet and infrared, that may be getting through the filter. Galileo's blindness in old age may have been caused by observing the sun.

End of scary rant.
Kudos on a fine instructable.

[tbh-1138]

I included a warning on the last step. I have no idea what wavelengths can get through 4 or 5 layers of floppy disk material, other than that it only lets red and orange through. I'm sure plenty of IR passes right through, as I've seen another instructable using a floppy disk as a filter for IR photography. It would be nice if there were a way to make a filter that first blocks everything but the UV, then shift the UV into the visible range. From what I've seen in SOHO and STEREO photos the sun looks awesome in UV.