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tinman
05-19-2005, 11:06 AM
Should I get that would equal a .007 inch (0.18mm) pinhole?
Thanks.

ImageMaker
05-19-2005, 03:59 PM
I don't know that there's a needle with a shank that small. #10 is the smallest common size, and it's more than twice that shank diameter. Best suggestion is to use the finest needle you have, and don't push it through, just dimple the pinhole material and then sand off the dimple with the finest sandpaper. Better to go too slow than too fast.

Looking for a 20 mm focal length?

Tom Persinger
05-19-2005, 04:17 PM
i strongly suggest going with one of the hobby drill bits, but you're looking to make a really tiny hole... i mean really really really tiny!

if you decide to go bigger, here's a chart:
http://bobmay.astronomy.net/misc/drillchart.htm

and american science and surplus has a great deal on a bit set for $10 USD:
http://www.sciplus.com/singleItem.cfm?terms=10979&cartLogFrom=Search

tinman
05-19-2005, 05:10 PM
Yup, 20mm. Thanks.

earlj
05-19-2005, 05:40 PM
That's a very tiny hole. I use hobby drills for most of my pinholes, and the smallest I know of is #80 at .343 mm (.014"). Imagemaker's suggestion will work - use thin material. The smaller the hole, the more the 'barrel' effect of the material thickness plays with your image. I found some .001" brass shim stock that is pretty delicate to work with, but it makes very nice holes.

You can always spend $20 on a laser hole.

Good luck. Show pictures.

ImageMaker
05-20-2005, 07:11 AM
I finally found some of that brass shim stock -- very nice to work with! I found it at an Ace Hardware store; they had brass, but not stainless steel, and in .001", .003", and .005". The .005" is too thick, I already had some of that and it's pretty heavy going with a needle. After working with the .001", I'd be tempted to try the middle ground of the .003", especially if I needed a hole that was too small to use any significant push through, but had to be just dimpled and sanded off. However, Earl is right, that the thinner the edge of the hole, the better. If you use a pretty blunt needle at first, you can thin the edge a lot when you sand off the dimple.

If you don't want to shop around for shim stock, you can try the thin metal from the upper part of a soda or beer can. The drawing process used to make those cans makes the metal thinner as you go up the side, thinnest just below the inward taper where the top is attached; common soda cans are around .002" or .003" in that region, but being aluminum, they're a little softer than brass shim stock, so it's not bad to work with. Aluminum foil on a roll from the supermarket (like Reynolds Wrap) is too thin, even the heavy duty stuff, but the foil used for semi-reusable pie tins and such works pretty well.

It also helps a lot to use very, very fine sandpaper, at least at the end stage. My most recent hole suffers from a rough edge, which makes the image fuzzier than it should be. Problem is I didn't have any sandpaper finer than 600 and I couldn't sand off some of the tiny burrs raised by pushing the needle through the hole to bring it to size. Before I make another hole, I need to find a model type hobby shop locally and get some superfine paper, the kind plastic model builders use for final sanding; I've seen it with grit down to 2000 (waterproof, on a plastic film backing, the stuff lasts almost forever, which makes the price a little easier to swallow).

I think you're going to have to make the hole, with the greatest of care, and be prepared to make half a dozen to get one small enough -- I don't think laser drilled holes suitable for camera use come in sizes smaller than about .010".

earlj
05-20-2005, 08:04 AM
Lenox Laser sells 100, 150, and 200 micron pinholes. The 200 is pretty close here.
http://www.lenoxlaser.com/pinholephotography/pinhole_photography_prices.html
$18 ea.

ElrodCod
05-20-2005, 03:39 PM
That's a very tiny hole. I use hobby drills for most of my pinholes, and the smallest I know of is #80 at .343 mm (.014"). Imagemaker's suggestion will work - use thin material. The smaller the hole, the more the 'barrel' effect of the material thickness plays with your image. I found some .001" brass shim stock that is pretty delicate to work with, but it makes very nice holes.

You can always spend $20 on a laser hole.

Good luck. Show pictures.


Earl,
Like you, I use jeweler's bits for my "pinholes" and I found a .5mm bit (about 012") at my local hobby shop for around a buck. There's also an outfit on the web that has bits down to .18mm for around 3 bucks each. I posted a link to it here at f/295 in a reply to Imagemaker but I can't find it. I lost all my bookmarks in a crash last week & I'll send you a link if I find it again.

Gary

ImageMaker
05-21-2005, 09:55 AM
Better check your math, ElrodCod -- 0.5 mm is about .019". The 0.18 mm would be .007", just right for the original request. However, get 3-4 -- you can break a bit that fine just trying to get it into the pin vise the first time...

taco
05-21-2005, 06:35 PM
If you don't want to shop around for shim stock, you can try the thin metal from the upper part of a soda or beer can. The drawing process used to make those cans makes the metal thinner as you go up the side, thinnest just below the inward taper where the top is attached; common soda cans are around .002" or .003" in that region,

ImageMaker,
Long ago, I've once seen the process of can drawing and therefore fully agree with you, but that was before my pinholer life and one thing I forgot to ask at the time which still is not clear for me: Is the thickness of a 1/3 litre can the same as of a 1/2 litre can ::)
Do you have any experience with different can sizes?
taco

ElrodCod
05-21-2005, 06:38 PM
Better check your math, ElrodCod -- 0.5 mm is about .019". *The 0.18 mm would be .007", just right for the original request. *However, get 3-4 -- you can break a bit that fine just trying to get it into the pin vise the first time...


My math is ok but my typing isn't. It should have been .3mm.

ImageMaker
05-21-2005, 08:36 PM
Taco, I can't tell you for certain. It varies between can makers, and by what's to go in the can -- beverages with less pressure actually get thicker cans, because the pressure inside keeps the can from crushing when stacked or bumped. My limited experience is that taller cans may be thinner at the top, but they might also be thicker at the bottom, depending on the specification of the company that buys the cans (the folks who fill 'em, that is).

Bottom line is the cans are made as thin as they can be and do their job, because the process costs the same regardless, and the less metal in the can, the cheaper it is. Easiest way to tell is to feel 'em. You can get a good feel for which cans are thinnest just by gently squeezing the full can -- though in all honesty, the difference between the heaviest drawn aluminum can currently used for beverage packaging, and the thinnest, is probably only about .001".

ElrodCod
06-20-2005, 02:11 PM
* It took me awhile but I finally found the supplier of micro metric drill bits. Here's the link. www.biscofl.com/metric_drill_bits.htm. They have bits down to .16mm (that's about .006")

Gary

moot
06-21-2005, 10:21 AM
If you want to use needles, go to a craft store and look for "beading needles". The package I bought had a range of #10 - #15. In the smaller sizes you'll need a pin vise to hold them, and be aware they are pretty flexible. The shank diameter is still bigger than you want, but you can do as ImageMaker suggests and not push it all the way through.