Using pinhole camera inside

friedakroket · 2025-11-10T08:16:27-0500

Dear everyone,

I’m experimenting with a pinhole camera and I’d like to use it indoors, without any developing process. My goal is to get an exposure of about 4 hours that still shows some kind of visible image of the space.

In my first tests, I left the camera up for 2 days, 5 days, and 8 days. The 8-day exposure obviously gave the clearest and sharpest result, but the other tests still showed some things of the rooms. I figured I needed more light if I want to be able to see anything with a 4 hour exposure, so for my next attempt, I added extra light sources.
I made another test using four different cans, all placed in the same spot but with different pinhole sizes, for 4 hours. However, in all the results, I can still only see the window, and nothing from the area where the extra lights were shining.

So now I’m wondering: Why is the window the only thing that shows up? Do I need more light sources? Is it even possible to get a visible indoor image this way?
Do I need to move the camera outside to get any kind of usable result?

Any advice or explanations would be really appreciated!

Thanks in advance

koraks · 2025-11-10T09:00:22-0500

Hi @friedakroket, welcome aboard (and I like your username, hehe!)

In the following I assume you're using darkroom enlarging paper for making these pinhole exposures; something like Fomaspeed paper. I also assume that you intend to create a pure print-out image that appears on the paper without any processing, like a lumen print. Is this correct?

The problem is most likely twofold:
1: While the extra light sources you placed may look bright to the naked eye, the difference in brightness between these lamps and actual daylights is likely several orders of magnitude.
2: Paper is generally more sensitive to blue and UV light, and less so to other parts of the visible spectrum. Artificial light sources (white light) intended for indoor use are usually quite rich in green and red parts of the spectrum, but much less so in blue and virtually lacking entirely in UV (assuming white LED lights). So the spectral output of your lamps may not be the best match for the paper.

In other words: your new light sources look bright to you, but they're still very dim to the paper.

You will simply have to provide for much, much more light - but the amount needed for what you're trying to do (get a print-out image through a pinhole) may be very impractical or even impossible to achieve. You've found that daylight works OK - I'd suggest exploiting that fact and photograph scenes instead that are directly illuminated by daylight.
Alternatively, you could drop the requirement of not developing the paper and instead develop it so as to get a far stronger image with less exposure.

friedakroket · 2025-11-10T09:35:02-0500

koraks said:
Hi @friedakroket, welcome aboard (and I like your username, hehe!)

In the following I assume you're using darkroom enlarging paper for making these pinhole exposures; something like Fomaspeed paper. I also assume that you intend to create a pure print-out image that appears on the paper without any processing, like a lumen print. Is this correct?

The problem is most likely twofold:
1: While the extra light sources you placed may look bright to the naked eye, the difference in brightness between these lamps and actual daylights is likely several orders of magnitude.
2: Paper is generally more sensitive to blue and UV light, and less so to other parts of the visible spectrum. Artificial light sources (white light) intended for indoor use are usually quite rich in green and red parts of the spectrum, but much less so in blue and virtually lacking entirely in UV (assuming white LED lights). So the spectral output of your lamps may not be the best match for the paper.

In other words: your new light sources look bright to you, but they're still very dim to the paper.

You will simply have to provide for much, much more light - but the amount needed for what you're trying to do (get a print-out image through a pinhole) may be very impractical or even impossible to achieve. You've found that daylight works OK - I'd suggest exploiting that fact and photograph scenes instead that are directly illuminated by daylight.
Alternatively, you could drop the requirement of not developing the paper and instead develop it so as to get a far stronger image with less exposure.

Dear Koraks,

Thanks for all of the information! It's really clarifying.
I am indeed using darkroom enlarging paper (Ilford Multigrade RC) inside of the pinhole cameras. I'm trying to imprint this paper to then scan it and edit it on the computer. (Like they do with solargraphy)

Do you think using a big UV-lamp (instead of a LED light) as an extra lightsource would help solve the problem? Or is this still not enough light compared to daylight?

If not, I think I indeed will have to move to places that are directly illuminated by daylight.

Thanks again for the already very informative answer!!

koraks · 2025-11-10T09:42:32-0500

The UV lamp may help, yes. If you have one, it's worth a shot. But I would start with something upwards of 100W real electrical power (the "300W" UV floodlights commonly sold are in reality around 75W), preferably a lot more. Keep in mind that exposure works logarithmically. This means that power requirements escalate quickly. If you're using UV, this means you will definitely need UV safety glasses to be in the room, and I wouldn't recommend spending much time in the room with those lights on anyway as UV glasses often don't wrap around your head seamlessly.

From a practical viewpoint, I would really consider the daylight option and develop the paper.

cliveh · 2025-11-10T15:42:49-0500

The sun is such a powerful light source, no artificial light source can come close to light from a window.

Using pinhole camera inside

friedakroket

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Using pinhole camera inside

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