Scanning Film Negatives Without a Scanner

I developed a roll of 120 film recently, but do not own a medium format enlarger or a scanner that will take them. After a bit of thinking, I found that by using a tablet computer as a back light I could take photographs with my mobile phone and use the phones image software to get quite nice results, at least for web use. The example below is taken straight from the ipad screen, without something to blur the pixels, and it is not converted to black and white, just to give you an idea of some very quick and rough results.

Materials:
Tablet or computer screen layed flat.
Turn of any lights that cause reflections. Draw the curtains if necessary.
A piece of semi translucent plastic or glass if the pixels are large on the back-light screen
A  smartphone
Some books or similar to hold the smartphone flat.
Photo negatives

Steps:
Lay the semitranslucent plastic on the computer screen to blur out its pixels
Lay the negative on the plastic with the matt side up. This is the side with the emulsion on, so be careful not to scratch it. Put something heavy on it to keep it flat.
Take a picture of the negative
Rotate and crop the picture as necessary.
Using the smartphones editing software either reverse the picture using a negative filter, or using a curves filter, move the ends of the curves from the top and bottom, opposite of where they were originally. (see second image)
Edit to perfection!


Elaborations:
Lomography has a commercial product that does the same thing. Their scanning app may be useful, but it is made for the specific focusing distance of their gadget. I have not been as successful in using it as the phones default camera app.

There are some versions of this that use a box or toilet paper roll to reduce reflections.

You can also consider building your own light source out of led´s and pearlecent acrylic or similar.

If you have a flatbed scanner you can use your camera as a back light to scan slides on the scanner as well.