Talk:Pinhole camera

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1 Calculating the f-stop & required exposure
2 DOF clarification
3 External links
4 A Pinhole Photographer/Wolf Howard
5 Black and White
6 Photo of Fire Hydrant
7 Invention
8 Worldwide Pinhole Photography Day
9 New Worlds Imager
10 vandalism
11 Fisheye or telephoto pinhole camera

[edit] Calculating the f-stop & required exposure

"The f-stop of the camera may be calculated by dividing the diameter of the pinhole into the focal length of the camera" The f-stop is the aperture, isn't it? shouldn't it say exposure time? Shouldn't it be "focal length"/"diameter"="exposure time"?

The f-stop is not just the aperture size, but rather the ratio between aperture size and focal length, if I remember right. 128.163.235.175 (talk)

[edit] DOF clarification

The article states: The depth of field is basically infinite, but this does not mean everything will definitely be in focus. Depending on the distance from the aperture to the film plane, the infinite depth of field means everything is either in or out of focus to the same degree.

It's not clear to me why infinite depth of field doesn't put everything in focus. The depth of field page did not help on this matter. Maybe I'm dense, but perhaps this article could explain this non-intuitive concept a bit more explicitly, at least as it applies to pinholes. --Ds13 03:03, 21 April 2006 (UTC)

A pinhole camera has a optimum distance between the pinhole and the imaging plane, which is the focal length. (Although that concept doesn't really make sense for pinhole cameras, as pinholes don't actually focus light.) All infinite depth of field means is that the focus is independent of distance (every distance is equally sharp), but the image can still be fuzzy if you deviate from the optimum distance (equally sharp does not imply sharp). --69.108.112.130 19:04, 9 November 2006 (UTC)

I'm pretty sure that a pinhole camera does not have an optimum distance between the pinhole and the imaging plane. As the imaging plane is moved further from the pinhole (i.e. "focal length" increased), the image gets larger, dimmer, and sharper. A user might choose an optimum image distance that suits their needs; say some distance where the image is both sharp enough for them and bright enough for them. But I don't think this is the same thing that the above commenter wanted to mean by optimal "focal length." I think user Ds13's question is a good one, and I'm going to delete the text that lead to the confusion. 128.163.235.175 (talk)

I think my earlier comment is basically wrong, and is perhaps disproved by the formula in this section of the article, that defines the optimal pinhole size in relationship to the "focal length" (distance from image plane to pinhole, in this case). I'm assuming that this formula gives the sharpest image? So that a larger pinhole increases blur due to plain old geometry, and a smaller pinhole increases blur due to diffraction? I still think that this part of the article is not as clear as it should be. If anyone agrees with me and knows how to improve it, go ahead; I'm not sure that I'll have the time to get to the bottom of this. 128.163.235.175 (talk) —Preceding comment was added at 16:18, 25 April 2008 (UTC)

[edit] External links

The external links section was far too big, especially for the size of the article. Several of the links seem to be providing the same info, just on different sites. I have put all the links below, so they can be hand-picked and put back into an external links section in the article. Even better, the information in them can be used to expand the article. That is where the information should be, not in an external link. Any links not required can be deleted from the list below. Please note: anyone connected with one of the sites below should not put it back into the links section. Tyrenius 01:09, 25 May 2006 (UTC)

[edit] A Pinhole Photographer/Wolf Howard

Is it just me, or does the section about Wolf Howard's methods seem very specific? I mean, those are generic steps in the process - shouldn't the general process be reflected somewhere in the article in a more orderly fashion? The quote from him is good, but I just think that some of what is in that section should be made more generic (though I can't tell if there will be a consensus for that, so I won't touch it for now). Also, I'm going to upload a picture of some pinhole equipment later (a camera and basic developing tools) if there are no objections. Douglas Whitaker 02:29, 19 July 2006 (UTC)

Good point. I put this section in, as I thought it would be of interest to show a more detailed picture of the process in action. I've tweaked it a bit to try to bring this out. Let me know if you think it's still not right. Of course, what would be good would be to give another example or two, preferably showing a completely different approach to it.

You are of course free to edit and contribute and be bold! Just make sure any images have the right copyright tags or they'll get deleted. If you're not sure, leave a note on my talk page and tell me the basis on which the pictures are being provided.Tyrenius 02:55, 19 July 2006 (UTC)

I like the changes you made but went ahead and added another sentence to further make the process universal as well as a link to Fox Talbot. I'll work on getting a picture of the equipment later today. Douglas Whitaker 17:41, 19 July 2006 (UTC)

I've tidied that bit, but it's not quite right yet. Tyrenius 18:38, 19 July 2006 (UTC)

Yeah, I'll try and type something up a bit later (though I don't know in what direction yet). I also uploaded the photos I was talking about. I wasn't sure if I should zoom in farther on the one of just the pinhole camera to further draw attention to the pinhole, but I thought doing so might detract from how small the hole really is. --Douglas Whitaker 20:26, 19 July 2006 (UTC)

Maybe lighten the image, as it's a bit of a black lump on my screen? Tyrenius 14:45, 20 July 2006 (UTC)

Yeah, I agree. I'll take the garbage bag off from around the pinhole camera and retake the photograph. Though, it'll probably have to wait another day because my account is less than 4 days old and therefore can't overwrite any images. --Douglas Whitaker 16:09, 20 July 2006 (UTC)

Wait or just upload it with a different name. If you do that, just put {{db-author}} on the image page for the redundant one and it will get deleted. Is the garbage bag for blackout? In which case, you could have both images, to show how camera is blacked out. Tyrenius 18:09, 20 July 2006 (UTC)

I uploaded the new picture and changed the image descriptions to reflect the purpose of the black plastic. If any other pictures of pinhole camera related things (equipment, negatives, prints, etc) are needed, just let me know and I'll try and get them. --Douglas Whitaker 02:53, 24 July 2006 (UTC)

I think you probably know better than me. Tyrenius 03:17, 24 July 2006 (UTC)

Is this whole section not just a ploy to plug a book? The last paragraph reads like an advert to me. —Preceding unsigned comment added by 84.92.211.29 (talk) 22:45, 10 February 2008 (UTC)

No, that para was added onto the section later. I've removed it. Tyrenius (talk) 01:07, 11 February 2008 (UTC)

[edit] Black and White

I hadn't paid that close of attention to the introduction to this article, but the latest edit (The defect of pinholes are that the pictures come out in black and white if a CCD without color filters or a black and white film is used.) raises an interesting point: Isn't that like saying that "If you use black and white equipment, you'll get black and white photos"? To me, this doesn't seem like a defect but rather common sense. If I'm mistaken, please tell me. --Douglas Whitaker 17:54, 20 July 2006 (UTC)

Deleted till clarified. Tyrenius 18:04, 20 July 2006 (UTC)

[edit] Photo of Fire Hydrant

If I'm not mistaken, the positive should also be a mirror image of the negative and not just inverted colors. --Douglas Whitaker 20:49, 10 January 2007 (UTC)

Best to make certain (find references) first. Tyrenius 23:51, 10 January 2007 (UTC)

The scene was photographed directly on photo paper. This gives a photo with inverted colours, but the image is not reversed. (A little confusing, but the lens projects a rotated image on the surface of the paper. Only when looking through the lens or through a transparency is the negative image reversed.) To get the positive image, the original photo is placed (image side up) on an enlarger directly on unexposed photo paper. Using a rather long exposure time, the (still not reversed) image is exposed to the photo paper through the negative photo to produce an image with positive colors. I hope I've explained myself clearly. --Matthew Clemente 15:47, 12 January 2007 (UTC)

For example, take a standard 35mm negative. Looking at one side produces a negative-color image, but it is not reversed. Looking at the other side gives a reversed image. And the print is not reversed either (in this case because the negative is placed backwards in the enlarger and the lens then projects a reversed-reversed image). --Matthew Clemente 15:51, 12 January 2007 (UTC)

[edit] Invention

Alhazen (Ibn Al-Haytham), invented Pinhole camera around 1000, Around 1600, Della Porta reinvented the pinhole camera. They didnot invent at the same time.

http://inventors.about.com/library/inventors/blphotography.htm

—The preceding unsigned comment was added by Itsalif (talk • contribs).

There were no facts or sources to support the claim that it was invented by any one person, so the sentance that claimed it had been was deleted.

—The preceding unsigned comment was added by 71.177.249.74 (talk • contribs).

[edit] Worldwide Pinhole Photography Day

I think this section could use a citation. The "Worldwide Pinhole Photography Day" home page at this URL http://www.pinholeday.org/ seems like a good source to use. Anyone with more expertise on this area care to comment? --Smiller933 21:46, 6 March 2007 (UTC)

Citations always welcome. Do put one in. Tyrenius 00:53, 7 March 2007 (UTC)

[edit] New Worlds Imager

It doesn't seem to be a pinhole camera, but rather a sort of coronagraph. Haven't done the research to be certain, but it looks like the pinhole camera was an earlier design for the project. Sho Uemura 19:14, 15 May 2007 (UTC)

[edit] vandalism

should this page be protected from vandalism? it seems it's getting hit. 71.196.48.107 01:41, 23 August 2007 (UTC)

[edit] Fisheye or telephoto pinhole camera

I put this comment on Talk:Fisheye lens but thought it might be more appropriate here.

A generalized pinhole camera having different refractive indexes on either side of the pinhole can perform either a fisheye or telephoto lens function.

In this case, the radius from the center of the focal plane to any projected point is still $R = f \times \tan \theta$ as with any pinhole camera, where $f$ is the focal length and $θ$ is the angle from the viewing axis to the point to be projected. In the general case, however, $θ$ is a nonlinear function of the refractive indexes and the position of the point to be projected: $\theta = \arcsin {\left( \frac{n_t}{n_f} \sin {\theta_t} \right)}$ , where $n t$ and $n f$ are the refractive indexes on the target and focal plane sides, respectively, and $θ t$ is the angle from the viewing axis to the the point to be projected, assuming the pinhole is at the origin.

If $n t < n f$ you have a fisheye pinhole lens. If $n t > n f$ you have a telephoto pinhole lens. Only in the special case $n t = n f$ do you get a "traditional" pinhole camera with distortion-free straight lines.

Of course, the chromatic aberration in such a camera would be terrible, but it's obvious that fisheye or telephotot effects can be accomplished with a pinhole, and it's easy to simulate such a camera in a computer without the aberration effects.

Is this too obscure, or is it worth mentioning this aspect of a pinhole camera? -Amatulić (talk) 00:04, 5 February 2008 (UTC)