Re: Pinhole Day Questions

Hi Patrick

So sorry to hear that your pinhole did not work; it does happen.

For what it is worth I think that the problem was the calculation.
From experience I would say that your exposure should have been around the 3
minute mark. Particularly for light toned subjects.

The way I come to this is as follows:

I have a camera with a focal length of about 7 inches.

On a normally overcast day my meter reading is around the 16 EV mark. This
using resin coated paper gives me a normal exposure of 6 minutes. The
pinhole I use is 0.024"

Pinhole is an imprecise art and the way I would make the translation in my
head is;

7" is nearly twice as long as 4" so I would require a quarter of time
exposure all else being equal = 1.5 mins.

The pinhole is nearly twice the diameter so lets say three times this
exposure = 4.5 mins

If you include alot of sky and light toned buildings then the time is
drastically reduced

Finally from what you have said about the total blackout I would reassess
this calculation and try at 3 maybe 2 minutes.

If you passed the needle right through when making the pinhole the
likelyhood is that the hole is larger than 0.148. Therefore the exposure
would be shorter.

If you can see a trace of detail amongst the black then you are not that far
off. What the heck try 1.5 or 2 mins

Now if you understood this you deserve a degree in foreign languages. I do
most of it in my head and then err on the side of ignorance.

If anyone wishes to take issue with what I have just said, please do!

Alexis

> Friends,
> I have taken a look at the current offering of this year's pinhole day
> images. All are terrific! What a wonderful project!
>
> I had a somewhat disappointing pinhole day, I am sad to say. I ran a very
> small pinhole "workshop". (I use quotes, because it was really just a few of
> my friends and I was only qualified to run this "workshop" because I had
> made and used a pinhole camera and they had not, more or less.)
>
> On Saturday we built our cameras. On Sunday we went out to shoot. As many
> already know, it was VERY rainy in New York, but we were lucky enough to
> step between the raindrops. We took pictures with oatmeal box cameras. Focal
> length approx. 4"; pinhole approx. .0148" (#12 needle); therefore approx.
> f/256 (rounded). We shot on Ilford Multigrade; approx. ISO 6?? An example
> exposure was approx. 10 min under heavily overcast skies.
>
> Here is the root of the question: All the negatives were black! I assume
> that we drastically over-exposed the paper. I do not think that it was
> fogged, but I suppose it is possible. The cameras were not light-leaky.
>
> Does anyone have any clues? Luckily, we all took a turn with my pinhole
> camera with Polaroid 669 film. Those were fine. But even so, I have a group
> of disappointed Pinholers on my hands.
>
> We will try again soon (obviously too late for this year's pinhole day and
> too early for next year's) so any help is appreciated.
>
> We did all have a great deal of fun, but it would have been nice to send
> everyone home with their own photo, taken with their own camera.
>
> --Patrick
Received on Tue Apr 30 08:50:36 2002