How to make clean hole

[eSPhotos]

Hi all,

I built a 4x5 pinhole camera that requires 0.56mm hole.
An empty coke can, 0.5mm dia needle and 800-1200 grade sandpapers were used to make the 'lens'.
However when I look closely with a high powered mag glass, the hole edges look rough like saw.
How can I make clean edged hole? Do you have any un-told tricks?
thanks

 

[2F/2F]

Once you are done sanding, you can go back with the same needle and twist it gently, taking care not to enlarge the hole any more.

 

[Jim Jones]

I found that .002" brass shimstock works cleaner than aluminum. Don't try to make the hole the finished size in one step. Instead, insert the needle a short distance through the material, sand down the bur, and repeat this until the desired size is reached. If any burr remains, a needle with the tip ground to about a 45 degree cone can be rotated in the pinhole to abrade away the burr. Pinholes the size of yours can be drilled with a no. 74 or 75 drill, perhaps obtainable at a hobby or model shop. A small pin vise is handy for holding the drill, needles, and other pinhole making tools. When using a drill, clamp the material between sheets of fairly hard material to reduce burrs. There is much information on making pinhole cameras and doing pinhole photography at http://www.f295.org/Pinholeforum/forum/Blah.pl.

 

[aaronmichael]

I've heard that "drilling" with the needle is better than poking straight through, kind of what 2F/2F mentioned. You didn't say which method you used though. I'd also advise trying your pinhole out on a camera if possible before you spend hours fretting about the perfection of the hole - it could be fine how it is despite the edges.

 

[eSPhotos]

Cheers guys,
2F/2F, generally that's how I make the hole - slowly drill (with needle) sand drill a bit more sand ... until I get the right hole size.
It looks okay but under a mag glass the edges don't look clean. May be I am unnecessarilly meticulous.

Good idea using brass shimstock, Jim. Also aperture blade of an old lens could be good too. Aluminum is easy to work with but too soft. Thanks for good advices.

aaronmichael, thanks for the advice. My camera has a focal length of 155mm and according to Rayleigh's formula the optimum hole size is 0.56mm. Fortunately it has removable 'lens board' so I can test a few different size holes (lenses).

 

[Rick A]

I've found that a jagged edge hole works good until a light source is in the field of view, then you get flair from the edge of the pinhole. You would get a bit of flair normally, but abnormally so depending on how ragged the hole.

 

[Jim Jones]

eSPHOTOS -- Some photographers consider Rayleigh's formula to yield too large a pinhole. Rayleigh based his formula on the scientific principles of 120 years ago rather than on the photographic experiences of today. I use Pinhole Designer with a user constant of 1.5 instead of the 1.9 Lord Rayleigh constant. This seems to give the best sharpness in the center of the image, although sharpness in pinhole photography is more subjective than objective. Some of us expend more energy in squabbling over optimum pinhole diameter than in taking photographs. It does provoke us into learning more about this suprisingly complex subject.

 

[Klainmeister]

First off....that title is great.

Second, I'd try the lens first before working towards "perfection". I found that my really nice, laser cut pinhole lens just produces boring images because they are consistent, sharp, and vignette little (that's due to focal length though). My favorite pinhole looks like a triangle under high magnification but produces great, interesting images. (Mine is made out of a beer can too)

Shoot, and if it's not what you want, experiment some more!

 

[Rick A]

I've been pondering something all morning. I was wondering if a red hot needle for drilling the pinhole would result in a cleaner hole. I quess I'll have to head for the workshop to try it out.

 

[nhemann]

I've made quite a few myself with good success rates - I personally like to use the credit-card sized diamond plates and wet sand them and I work from both sides once the inital hole is made. If you have a larger needle on hand, once the hole to size insert the point as far as it will go and gently turn it without enough effort to expand the hole further. It will burnish any jagged edges that might exist and help true up the circularity as well. Do it from both sides as a final measure and you are good to go.

PS these are the plates I talk about (amazon should have them but they are not hard to find in any case) -the 600 grit works just fine but you may want to use the 1200 to finish but it takes forever to do it all with that one:
http://theconsumerlink.com/DiamondMachiningTechnology/detail/TCL+D3F/0

 

[eSPhotos]

Thanks all for good informative comments and advices.

I have taken a few photos yesterday with new 'holes' of varying sizes of 0.4, 0.5 and 0.6 or there about.
To me they all produced same blurry un-interested images.
Maybe I am expecting too much from the pinhole.
Maybe I need shorter focal length to accentuate distorsions and/or vignettes to make the images interesting.
I had a good fun building it so don't mind going back to my working shed.
Any good or interesting focal lengths for 4x5?

 

[Klainmeister]

I used a 65mm and I believe a 45mm, with the 65mm being my preference because it had enough vignette to show the pinhole-ishness well, but wasn't a circle.

 

[guitstik]

I just pound a hole and eye-ball it then shoot away and have fun. Putting to much thought into it just ruins it for me.

 

[eSPhotos]

cheers guys.
Liked your philosophy Guitstik. After all, pinhole is to have fun.

Just done a calc and yes 65mm FL gives good vignette as it's image circle is about 5 inches.
I might draw up a plan ...

 

[Nicholas Lindan]

My [4x5 pinhole] camera has a focal length of 155mm

That's too long a focal length for 4x5. A 150 fl is better suited to 8x10.

If you made an 8x10 print from your 4x5 negative it would have twice the fuzz of a contact print. So if you started with an 8x10 negative to make an 8x10 print then the fuzz doesn't get magnified.

Try a 65mm or so focal length.

To prevent vignetting the pinhole must be very thin. The real reason for the dimple and sand technique is to produce a pinhole with a razor edge to it. Don't use a needle of the size of the pinhole - use one that is considerably larger. You don't make the hole by pushing the needle through but by using the tip of a much larger needle to make a nice dimple.

You can examine and measure the pinhole by putting it in the enlarger's negative stage and looking at a 10x blow-up.

After the hole is almost, but not quite, big enough with sanding use just the tip of a smaller needle (one still larger than the hole) to burnish the hole to the right size.

 

[Jim Jones]

. . . Maybe I need shorter focal length to accentuate distorsions and/or vignettes to make the images interesting. . . .

Yes. Blur is directly proportional to the diameter of a correctly sized pinhole. Therefore, you can get sharper photos if desired with shorter focal lengths. Extreme wide angle lenses are expensive, but pinholes of all focal lengths cost the same. The apparent distortion inherent in wide angle photography is a valuable tool. National Geographic often uses it.

 

[jeffreyg]

For those looking for accurate size drills for pin holes, round dental burs come in .3mm increasing by tenths of a mm up to 2.7mm.

http://www.jeffreyglasser.com/

 

[moki]

I like to use aluminium foil that's about twice as thick as the usual stuff for kitchen use, but still far thinner than a coke can. I get it from some packaging, but hardware stores could have something similar. Just put it on a relatively soft surface (piece of cardboard), and use a thin sewing needle to drill a hole by holding it between thumb and middle finger and resting the index finger on top (no pressure, the weight alone is enough!). Finally, I just turn it around, drill again from the other side and sand both sides very carefully. Depending on the drilling time, pressure and needle size, I can get almost perfectly round holes from 0,15mm to 0,6mm almost every time.

And please don't worry too much about the pinhole size and shape. 0,56mm might be the optimum for your focal lenght, but you'd also get a (less sharp) picture with any other size of hole. 50% more or less don't matter much at all. I tend to use a size, that gives me a usable aperture around f/150-200, not necessarily the "optimum size". Same for the perfectly round shape... sure, it gives the sharpest pictures, but a few microscopic pieces of metal won't make your pinhole unusable. Pinhole cameras are very simple devices - no need to over-engineer it.

...and that "blurry and uninteresting" is part of pinhole photography. You just can't get the same shaprness as with a lens. And just like any other camera (or tool in general), a pinhole camera needs some skill and experience to use properly and get interesting results. An ultra-wideangle can help with this, as it gives perspectives, that are usually not possible in lens-based photography. I love my tiny matchbox pinhole cameras for 35mm film... they're even less sharp than any 4x5, but I came to like the effect. Just remember that this is not "normal" photography, it's a completely different kind of taking a photo.

 

[aaronmichael]

Thanks all for good informative comments and advices.

I have taken a few photos yesterday with new 'holes' of varying sizes of 0.4, 0.5 and 0.6 or there about.
To me they all produced same blurry un-interested images.
Maybe I am expecting too much from the pinhole.
Maybe I need shorter focal length to accentuate distorsions and/or vignettes to make the images interesting.
I had a good fun building it so don't mind going back to my working shed.
Any good or interesting focal lengths for 4x5?

Like some of the other folks on here said, try changing your focal length and if that doesn't work then I'd try making some more precise pinholes. Personally, I was AMAZED when I started using my home made pinhole's. I could not believe how ridiculously sharp they were for being home made. I make my pinholes with sanded down aluminum from soda cans and sewing needles. Anyway, that's why I found your "blurry and uninteresting" comment a little strange - because if I can do it, anyone can Try checking out http://mrpinhole.com/ if you haven't already. The site is nice because it will tell you how long your focal length has to be in order to cover a certain size (like 4x5 or 8x10).

 

[DWThomas]

As far as "uninteresting" goes, I think some attention to subject matter can help too. The infinite depth of field and often wider than usual field of view can enhance results with relatively simple and dramatic compositions as opposed to "busy" detailed landscapes. I tend to look for things like "infrastructure" -- bridges, railroads, industrial buildings, dams, large power or pumping stations (all the stuff that results in phone calls to Homeland Security! )

My 2¢,

DaveT

 

[bblhed]

....................Pinholes the size of yours can be drilled with a no. 74 or 75 drill, perhaps obtainable at a hobby or model shop. ..........

I assume that the whole world is in inches.

A # 74 drill is .0225" [.571mm] in dia
A # 75 drill is .0210" [.5334mm] in dia

Here is a link to a drill chart.

http://www.carbidedepot.com/formulas-drillsize.htm

I hope that at least the drill chart helps.

 

[Joe VanCleave]

Great advice, all.

I'll add that there's a tradeoff between wanting an ultra-high focal ratio for intended sharpness and then losing that sharpness with the extra-long exposure times and possible camera movement blurring the image. Focal ratios around f/150-250 are often satisfying, of course depending on format size and focal length.

Larger sized formats will also give you more information and perceived sharpness, since the negatives can usually be contact printed rather than enlarged, and there's more information present if scanning.

Also, tonal range is at least as important to me as sharpness. Good tones, good composition and interesting subject matter are all more important to me than mere sharpness. In the end, a pinhole camera is still a camera, and thus all the essential elements of a good photograph are still required.

Looking forward to seeing more of your work.

~Joe

 

[eSPhotos]

Indeed, great advices.
My biggest mistake was not asking you guys before I start sawing timber.
Well, now I am back to drawing board so stay tuned for chapter 2 ...