pin hole experiment surprised me

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Beach Bum - 08 Feb 2006 19:29 GMT

I fully expected to see the image created by the pinhole on my focusing
screen up-side-down. Then I realized that the lens also creates an inverted
image and the SLR already corrected that for me. Hah, that's pretty nice.

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Pete D - 08 Feb 2006 19:42 GMT

Yes indeed. Did you know that you can also make a pinhole zoom?

>I fully expected to see the image created by the pinhole on my focusing
> screen up-side-down. Then I realized that the lens also creates an
> inverted
> image and the SLR already corrected that for me. Hah, that's pretty nice.
> :)

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Beach Bum - 08 Feb 2006 19:43 GMT

> Yes indeed. Did you know that you can also make a pinhole zoom?

I read that, but haven't found out how yet.

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Rich - 08 Feb 2006 23:30 GMT

>> Yes indeed. Did you know that you can also make a pinhole zoom?
>
>I read that, but haven't found out how yet.

Just make a couple tubes that allow you to vary the distance of the
pinhole from the sensor. Length = focal length.
-Rich

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Paul Furman - 09 Feb 2006 03:35 GMT

>>>Yes indeed. Did you know that you can also make a pinhole zoom?
>>
>>I read that, but haven't found out how yet.
>
> Just make a couple tubes that allow you to vary the distance of the
> pinhole from the sensor. Length = focal length.

Is it feasible to make a really wide angle like 10mm at 0.4 inches from
the sensor? Is the math that simple? Vignetting would decide how wide
was possible.

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RichA - 09 Feb 2006 05:52 GMT

Yes, but you have to experiment with different hole diameters to see
which size
offers the best image. Precision pinholes (available from places like
Edmund)
are better than holes punched in thick card stock or aluminum foil.

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David Dyer-Bennet - 08 Feb 2006 21:30 GMT

> Yes indeed. Did you know that you can also make a pinhole zoom?

I've got on in 35mm (macro bellows and body cap), and could make one
in 4x5 farily easily (poke a hold in a lensboard-size sheet of metal,
mount it on the monorail viewcamera).

Although my existing 35mm body cap has a hole sized wrong for optimal
resolution at most zoom positions on the macro bellows.

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JPS@no.komm - 08 Feb 2006 23:59 GMT

>Yes indeed. Did you know that you can also make a pinhole zoom?

I didn't make a telescoping tube, but I have made a pinhole in a SLR
body cap and used it with extension tubes.

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Eric Schreiber - 09 Feb 2006 15:10 GMT

> I didn't make a telescoping tube, but I have made a pinhole in a SLR
> body cap and used it with extension tubes.

Hmmm. Now that's an interesting idea for me to tinker with. I like
experiments with low entry fees :)

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Rich - 09 Feb 2006 23:24 GMT

>> I didn't make a telescoping tube, but I have made a pinhole in a SLR
>> body cap and used it with extension tubes.
>
>Hmmm. Now that's an interesting idea for me to tinker with. I like
>experiments with low entry fees :)

Mount the thing in a long wrapping paper tube, then put
an eyepiece in one end and you have a pin hole telescope.
Or a long telephoto.
-Rich

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