Blackening a pinhole?

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Jerevan

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I bought a secondhand pinhole camera (LeRouge) that has a pinhole that is not blackened (i.e. shiny brass on front and on the back). I suppose there will be some contrast loss.

Is there some good way to "blacken" the brass around the pinhole? Does a sharpie work, or is there something better? I can't take the brass disc out of the camera.
 

Donald Qualls

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On the front (outside the camera) it doesn't matter. For inside, when I'm making a camera, I usually use a black Sharpie or other permanent marker -- the ink is dye based and won't clog or change the shape of the hole. Get the fine point variety, and you might be able to blacken the inside of the pinhole without disassembling the camera.
 

Donald Qualls

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Matte black spray paint for metal. Black cloth hockey tape. Black electrician's tape.

None of which are suitable for the actual brass sheet with the pinhole in it -- but work pretty well (except for the glossy electrical tape) for the interior surfaces of a camera.
 

DWThomas

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There is a chemical that will blacken brass and some other copper alloys. I have one called "Blacken-It" that was available through model railroad shops, used on brass model locomotives, but I just now found comments that it is no longer made. There are several others that show up in supplies for marine models and gunsmithing. I have also heard that some photographic toners work, but have not had any success doing that. The beauty of using a chemical is minimizing any dimensional alterations or blobs in the pinhole.

It takes about one Q-tip worth of Blacken-It to do a pinhole, so my orphaned 6 oz bottle will probably carry me thru ...
 

Andrew O'Neill

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None of which are suitable for the actual brass sheet with the pinhole in it -- but work pretty well (except for the glossy electrical tape) for the interior surfaces of a camera.

Why? Works for me. In fact I have black spray paint on one that the shop teacher holed for me. The metal paint he has works great.
 

Donald Qualls

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Paint has a high potential to clog the pinhole, especially if it incorporates a flattening additive -- and even if it doesn't completely clog, it can alter the size or shape of the hole. Tape on the inside of the hole sort of works, but can't cover 100% of the exposed bright metal (perhaps enough that it doesn't matter, though). Glossy electrical tape is better than bright brass, but only just.
 

Grandpa Ron

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I use a black marking pen on both sides. Some are less glossy than others but they all seem to work. I also make sure the hole is clear with the same pin I used to make it.

Good Luck
 

Andrew O'Neill

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Paint has a high potential to clog the pinhole, especially if it incorporates a flattening additive -- and even if it doesn't completely clog, it can alter the size or shape of the hole. Tape on the inside of the hole sort of works, but can't cover 100% of the exposed bright metal (perhaps enough that it doesn't matter, though). Glossy electrical tape is better than bright brass, but only just.

The applied paint is so thin its negligible Lightly inserting the tip of a pin in to the hole before spraying will keep the hole clean.
 
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Jerevan

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Thank you for your suggestions - I am going the marker route. The insides of the camera is in its natural wood colour - would it make any sense painting that, or should I just leave it?
 

Donald Qualls

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I've had good results blackening the insides of wood cameras with india ink -- you can get a small bottle for a couple bucks at Dick Blick or Michael's (or similar), brick and mortar (when they reopen) or online. A small plain brush will help, too. It's very, very black, but doesn't affect the wood grain texture (which can be nice to see, to remind yourself it's real wood). I'd do the film chambers as well as the dark box behind the pinhole -- in fact, all internal surfaces that aren't visible when the camera is closed -- to get the best image quality/lowest fog level.
 

John Koehrer

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How about blackening it with candle smoke?
 

Helge

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Exactly.
Lampblack (soot) was long the gold standard for black, and is still the cheapest way to get large quantities of really deep black.
The only important thing to blacken is the very edges of the hole. As absolutely atomically thin as they sometimes are.
You need to get some very smooth and small-particled fuel to make soot that doesn't (even partially) clog the hole.
A candle is probably not going to cut it.
 

Donald Qualls

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Kerosene soot used to work very well for lampblack (and is the source of the term).
 

Grandpa Ron

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I would be an interesting experiment to see how much difference blackening or not blackening really makes.

I have added 4 to 5 inch long, 2 inch tubes to my 35 mm camera for larger f numbers and even with flat black paint, I seem to get darken areas in the center on long exposures which I attribute to light reflection with in the tube.
 
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Jerevan

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Lampblack is a good idea ... if it wasn't for the camera being made out of ... wood. And it is hard to reach inside it too. I used some sepia ink for the innards (might redo with a black india ink), and then a Pigma Micron for the brass, on both sides. Looks better but there is still a discernible difference compared to "pre-blackened" cameras. I am going to run a film through it and see.
 

Helge

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Mask it off with tissue paper and two or three layers of tinfoil. And only sooth it from the outside.

Remember it’s just the actual hole you need to blacken.
With soot you can always very carefully clean it with a sharpened toothpick or needle.

Paint or ink could prove to be impossible to remove if it clogs the hole.
 
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If you have part B sepia toner around you can use that to "blacken" the brass. You have to clean it first though with some acid. Stop bath or vinegar will work. You'll end up with a dark brown. It won't be black, but it will be matte and dark and it is a chemical solution to your problem so your pinhole will still be a pinhole. As was mentioned above, you only need to blacken the pinhole itself. Nothing else matters.

If you really want to darken the inside of a camera to prevent reflections, paint alone won't do it. i use fine silica sand combined with a flat black paint. The textured surface pretty much eliminates all reflections. I had to do that with my Holga wide angle pinhole camera since the design made reflections a big problem.

Hope that helps you.
 

europanorama

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Musou the darkest black ever. 50ml around 45 usd. i painted Scura(35mm), Scura 120(former scura 66) inside. on scura i added velvet at curved back inside.
I also painted other pinhole-stuff and cams. next is checking if musou is waterproof. maybe it must dry longer than other paints. i used other paints to add grip on scuras(have 3) plus the 66. es also have leather for 66. maybe better painting first and searching for a paint with grip. they exchanged filmtransport knobs with knurled ones. yes i also painted both version since 3dprinted they have less grip. will now test first if painted knurled or unknurled has better grip. yes filmtransporting there is quite stiff which is good for filmflatness. and film-exchange is a different more complicated chapter. we will see. 65mm viewfinder of MUP matching best 30mm equivl. 60x60 scura 120 or 25 x60mm scura.
there is also a very dark MUSOU? velvet only lost link.
since i painted special bessa I (P67-mount register reduced by 38mm) without bellows/lens i will show how is affecting musou added on velvet.
 

Helge

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Musou the darkest black ever. 50ml around 45 usd. i painted Scura(35mm), Scura 120(former scura 66) inside. on scura i added velvet at curved back inside.
I also painted other pinhole-stuff and cams. next is checking if musou is waterproof. maybe it must dry longer than other paints. i used other paints to add grip on scuras(have 3) plus the 66. es also have leather for 66. maybe better painting first and searching for a paint with grip. they exchanged filmtransport knobs with knurled ones. yes i also painted both version since 3dprinted they have less grip. will now test first if painted knurled or unknurled has better grip. yes filmtransporting there is quite stiff which is good for filmflatness. and film-exchange is a different more complicated chapter. we will see. 65mm viewfinder of MUP matching best 30mm equivl. 60x60 scura 120 or 25 x60mm scura.
there is also a very dark MUSOU? velvet only lost link.
since i painted special bessa I (P67-mount register reduced by 38mm) without bellows/lens i will show how is affecting musou added on velvet.
Actually a certain amount of bounced light in a pinhole camera is desirable. It flashes the paper and film and makes it faster and raises the shadows.
 

radiant

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Buy acrylic paint that is used for brush painting. Easy to get in tubes, easy to apply with brush (and fun).

I wouldn't have anything non-black inside camera. Strange that such pinhole manufacturer leaves inside of the camera like that. It must be a mistake.
 

Barry Kirsten

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Liver of sulfur from a jewellery makers supply is good for blackening brass. It's a chemical reaction with the brass that causes the blackening, rather than a coating like paint or soot which may clog the pinhole aperture. The brass should be cleaned with a weak ammonia solution first or the gel will not take. I did my first pinhole unaware of this and the result was disappointing. Details can be found online at www.cooltools.us
 

europanorama

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Actually a certain amount of bounced light in a pinhole camera is desirable. It flashes the paper and film and makes it faster and raises the shadows.
yes also thought of that. There was a CPA called device-Concurrent Photon Amplifier- which with four flashes in the corners fogged the films during shooting. Bob Schwalberg reported in Popular Photography maybe Modern Photography. Must check. Pity i didnt buy in early 80ties around 1200 usd or more.
I did accidentally puncture a 18° by cosmos circle pinhole plate when mounting with a spanner wrench. sharp tips must be shortened to no perforate the foil. have now two tiny holes for fogging. one can also prefog after testing it out if needed. I think i will be finally able to start with all my exotic constructions/combinations incl. the genious rotashift-lens (28mm shift on any position) by Custom Camera Building. he cannot actually 3DPrinting. Only by the end of 2022 or later. ask him. he is in canada.
 
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