Digital pinhole

[hecya]

I have made a pinhole using an old camera body cap for my 20D and the results are ineteresting but kind of bland. The attached picture was shot in RAW and later converted to grayscale and from then to duotone. The pinhole diameter is 0.30 mm, esposure time is 0.8 secs.
I wonder what is the best option to regain sharpness on a Mac.

[hecya]

I forgot to add that you are free to try this image to improve the focus/sharpness.

By the way, my avatar picture was taken with the same pinhole cap.

[adas]

How you know your pinhole cap is 50mm?
Here is the image sharpened.

[hecya]

I was using a pinhole calculator. The focal distance is about 48 mm from the sensor plane to the pinhole. So the "lens" is about 50 mm. I tell about because measuring the pinhole with a microscope is not exact. The sharpened image looks pixelated, maybe the resolution is not the same?

[adas]

Hecya, you won't be able to sharpen that image as the highest frequencies were lost due to diffraction caused by the very small aperture.
I assumed the frequency dropped 4 times, so I took your image and resized to 25%, than sharpened that. Than ofcourse resized back to what it was and posted that.
The truth is that the 20D has too small of a sensor to be used as a pinhole camera. At least a 4 times bigger sensor should be used to obtain very good results, while still maintaining the 20d's resolution.

[hecya]

So you would think that I should reduce the image to 25% always in order to regain some sharpness. That is interesting.Thanks for your response. I will make some samples.

[rpolitsr]

Nice shot hecya. The thing I like most in pinhole photography is the perspective of the image.

Some time ago I did a few pinhole pictures with my Canon A1 (film SLR) using very thin aluminum foil and a very small pinhole.

The pictures were a bit soft, but certainly sharper than your sample.

I am not sure about all the optic’s theory involved, but I think your old lens cap wall is thicker than the aluminum foil. The thickness may contribute to the soft image obtained.

Unfortunately, I am unable to play with pinholes in my digital Canon Pro1 because of the permanently attached lens.

[hecya]

I used a piece of aluminum foil and also tried with a 0.15 mm thick aluminum printing plate and the results were very similar. I checked with a microscope and the hole is round with no debris on it. I tried also with a smaller pinhole but the results were worse I guess because of the diffraction. So I wonder what I did wrong or if this kind of sharpness is all it is. I used a tripod for picture taking.

[adas]

I am not so sure anymore that the diffraction would be the main cause of the blurring in the image. In fact, I think that diffraction only plays a minor role in that.
The big problem is this:

[adas]

Usually, a lens have two focal (concentrating) points. It takes the light from one and put it in the another one.
The pinhole has no focal points. So a pixel will receive the light from an area wich could include a bunch of objects in it, causing immense blurring.

[hecya]

I have made a new pinhole, this time about 0.25 mm that, according to several calculators, is the ideal. The result I guess is a bit better. This picture was taken at 1.8 secs, ISO 1600 in RAW. Converted to BW in DPP ans scaled down in PS.
What do you think about its sharpness?
This time I literally took about an hour making the new pinhole and tried to control the shape and dimensions with a microscope and the resulting hole was way better than the one I used for the first picture. I wonder if buying one of those laser drilled would make a huge difference.

[bubba zanetti]

I wonder if buying one of those laser drilled would make a huge difference.

G'day hecya. Ive never tried any digital pinhole but from my film stuff i remember that my apertures were pretty well around the .3mm & i used some 0.25mm (i think) brass shim. In bright daylight i could go from 1 to 2 mins exposure. I used to drill the shim with a dremel and always then squashed a black marker into the hole to darken the edges inside the hole & stop any flaring. I would often sit on f400 so focus was not really an issue.

Keep trying though as im sure others here are as interested as i am with your results.

[sally_tomato]

the diagram looks more like this:
http://farm4.static.flickr.com/3215/2803713141_0b76e1dc51_o.jpg
from what i recall from college photog class, smaller diameter yields better results, and thickness of the material and a clean, round hole are very important. instead of drilling i would try punching a hole--with help of microscope you should be able to clean the hole up. then be sure to face cleanest side out. in any case, the sharpness you seem to be after is hard to come by. reducing the size of the 'printed' image will help of course. you seem to be off to a great start, keep at it!