I tried to make my DSLR into a pinhole camera today by cutting out a thin piece of cardboard, and poking a thumbtack through the middle. The images are extremely blurry, and I'm wondering if the hole is to big, or if something else is the issue here. Perhaps it may not work with a DSLR. Does anyone know anything about pinhole cameras? Here are some test pics.

This one is my curtains.
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Here is a self-portrait from about 2 feet away.

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Last is some alcohol bottles, because the stereotypical drunk has blurry vision.

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