How sharp can you get a pinhole image?

[Denis P.]

I made a couple of wooden pinhole cameras, based on Zero Image design, and used a laser-drilled (EMS) pinhole, purchased from USA. FL is 30mm, which is about right according to Pinhole Designer software (link in one of the previus posts), with the constant of 1.5 (instead of the default 1.9).

I'm pretty happy with the results: one camera is 6x6 format, and the bigger one is a combo 6x6 - 6x9 camera, and that one uses the same FL and pinhole size (0.2 mm, i.e. 200 microns and 30mm focal length).

Attached are a few results.

 

[paul_c5x4]

The finished pinhole plate was blackened with BlackenIt, a mysterious liquid found in model railroad oriented hobby shops.

Selenium toner also works quite well for blackening brass, as does sulphide toners.

 

[ezwriter]

Great images! What do u use to make a pinhole the exact size?

 

[DWThomas]

Selenium toner also works quite well for blackening brass, as does sulphide toners.

Yes, I've heard this but my attempts to do it weren't very successful. I don't know if it was an issue of concentration or pH or what. The model RR stuff is able to easily do a weathered black railroad locomotive finish on brass. It is a tad pricey, but so is toner!

 

[DWThomas]

Great images! What do u use to make a pinhole the exact size?

In my case 'exact' is a relative term! As I mention my process is iterative, I go a ways and then measure. If the hole is too small, I do a little more. If too big, enh, start another one. But in the end, the dimension is important, but not all that critical, it's just nice to know what it is for exposure calculations. A very gentle teasing with a spinning motion of the needle can also help round the hole.

I assume with the laser drilled holes some sort of industrial numerically controlled machinery comes into play.

 

[Klainmeister]

In my case 'exact' is a relative term! As I mention my process is iterative, I go a ways and then measure. If the hole is too small, I do a little more. If too big, enh, start another one. But in the end, the dimension is important, but not all that critical, it's just nice to know what it is for exposure calculations. A very gentle teasing with a spinning motion of the needle can also help round the hole.

I assume with the laser drilled holes some sort of industrial numerically controlled machinery comes into play.

Exactly. Puncture lightly, sand down, spin the needle and then I place the pinhole on the scanner and take it into photoshop to measure.

 

[ColRay]

"Exactly. Puncture lightly, sand down, spin the needle and then I place the pinhole on the scanner and take it into photoshop to measure. "

wasn't that easy when I had a go!