How does this TLR camera expose properly?

Question

I found a DIY TLR camera kit that lets you build the camera from parts, then use it to take photos. What I don't understand, is that the specs list:

1/150s shutter speed; f/11 aperture

From that description, it makes it sound like it has a fixed shutter speed and aperture. Assuming I use 24 or 36 exposure 35mm film, am I limited to one set of exposure values for the entire 24 or 36 frames? I am thinking I might be misunderstanding how TLR cameras work.

Answer

This is very similar to a Holga medium-format toy camera, where the shutter speed is approximately ¹/₁₀₀th of a second (give or take the particular camera you have and how it is feeling today) and the aperture is about f/13 (regardless of whether you have the alleged aperture lever set to one of its two non-functional options).

So how do you get the exposure right? You shoot in lighting that's right for the film speed you've chosen. You depend on the greater exposure latitude of film when it's off by a bit, and don't worry so much about getting it perfect. Or close to perfect. If you wanted it perfect, you wouldn't have a plastic DIY camera, right? Rather than control and execution of vision, it's about happenstance and creation through serendipity.

PS: this isn't normal for TLR cameras in general. It's normal for toy cameras, though.

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Is there an easy way to force chromatic aberration?

Question

A couple of months ago I was playing with my camera and a magnifying glass and I noticed that this glass produced a very soft chromatic aberration. Here's an example:

(Here is the full size, 18mp image)

Altough the effect was pretty cool, I couldn't focus too far from the lens. Here's another example, but with an object to a few meters farther.

Maybe at this resolution the dog seems to be focused, but in the full picture you can notice that it isn't. Also the CA effect isn't that pronounced as in the first picture. (For pixel peepers, here's the full size image)

So, is there an easy way to produce chromatic aberration? I know that there are some lensbaby optics that can do that, but I'm looking for something like DIY.

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ADDENDUM

Just a random thought: Could I emulate it by shifting the color layers of the image? I mean, the image is composed by three diferent layers of color, if i offset them a few pixels, will that produce some CA?

I'm pretty sure that the colors of the photo will go nuts, but maybe there's a related solution.

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ADDENDUM ADDENDUM

I'm offering 300 sexy points of my own reputation for a cool, nice and DIY solution for this. Go go go!

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LASTUM ADDENDUM ADDENDUM

Well, this wasn't easy. Coneslayer gave me the best answer, but Autopulated gave me the most easy, direct and (not-so) DIY solution. So:

1) I've accepted Coneslayer answer

2) I've gave the 300 sexy points to Autopulated

Thanks for your help, you both are awesome!

Answer

I think the dog is in focus, but it's not sharp. And it's not sharp because a magnifying glass isn't corrected for any aberrations, chromatic or otherwise. In other words, it's a technically poor lens (though you're still welcome to have some fun with it, of course).

Lenses focus light by slowing it down as it passes through the glass, which bends the rays ("refraction"). But glass slows down blue light more than red light, bending the blue light more strongly, so the different colors come to a different focus. We say the refractive index for blue light is greater than for red light, and the fact that they're different is called dispersion, and the difference can be expressed as a dispersion index.

While all types of glass are dispersive, some are more dispersive than others. If you combine two lens elements made with different types of glass in the right way, one with a high dispersive index and the other with a low dispersive index, you produce an achromat, which reduces the chromatic aberration by bringing red light and blue light to the same focus. Pretty much any camera lens provides at least this level of correction; your magnifying glass does not. An achromat still has some residual chromatic aberration; for example, green light may come to a different focus than red and blue. Further correction produces an apochromatic lens.

If you swapped the glass type for the two elements of an achromat, it seems like you would end up with a system that exaggerates chromatic aberration. You might be able to source the required elements from an educational supplier like Edmund Scientific. Or you could just try to find a convex singlet (like your magnifying glass) made from a high-dispersion glass, which may be called "flint glass."

There are lots of other lens aberrations besides chromatic aberration: These include spherical aberration, which degrades sharpness. Your magnifying glass is, again, uncorrected for spherical aberration, which contributes to the lack of sharpness. In a real camera lens, spherical aberration is corrected through the use of multiple lens elements and/or aspherical lens elements, which are more difficult to produce than spherical elements (whose surface conforms to the surface of a sphere).

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How do I get a a soft, washed-out film effect with a digital camera?

Question

I use digital for the convenience aspect of it, but sometimes I take a picture and can't help thinking that the soft, slightly "faded", washed-out look would be nice. How would I go about getting such an effect in post-processing, and what (if any) in-camera settings are required to do a good job?

Answer

The answer you don't like - out of all the digitally added film effects I've tried (and I've tried many along with actually shooting film) none really come close. That is not a scientific type of knowledge, but rather an impression. So if you really really want film look, you'll end up shooting film and even then, you'll most probably be disappointed on how far your results are from the film icons.

In many cases what is perceived as the film effect is not just a film effect, but photographer's creative vision put into right film choice and shooting technique plus the specifics of the emulsion plus photographer's editing. Harald Mante's Kodachromes are worlds apart from Steve McCurry's Kodachromes (again, personal impression based on the books, can't provide a reference).

The answer you might find useful - Nik Software's Color Efex Pro plugin contains many color film emulations and their Silver Efex Pro contains B&W film emulations. Other than that, DXO FilmPack also has pretty decent choice of films. These are the ones I've tried myself and can recommend, although this is not a guarantee of realistic rendering. Based on just web examples, Alien Skin Software's Exposure also looks interesting (I'm looking forward to try out their Kodachrome emulation).

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What is a zone plate?

Question

I was looking into alternative methods of photography and I happened upon something called a 'zone plate.'

Three questions:

1. What is a zone plate?
2. How does it work?
3. What can I do with it?

Answer

Summary

A zone plate is a way of focusing light, like a lens, but using Fresnel diffraction instead of refraction. This is cool from a theoretical point of view, because it demonstrates the wave nature of light. And it's cool from a photography point of view, because the images produced have a unique glow, with a impressionistic almost-painted look. If you're attracted to a certain lo-fi "old-camera" aesthetic, using a zone plate is a way to get it authentically, rather than faking it in post-processing.

Construction and Principles

The plate, which is a small piece of glass, plastic, or something else relatively transparent, is inscribed with concentric opaque circles. In order to create a focused image, these are placed so that the interference creates zones of "constructive" interference, forming a focused image. The D.I.Y zone plate web page Whiz Kid Technomagic Zone Plate Designer explains the math and pratical physics behind the choice of size and spacing quite nicely. And the Wikipedia article on zone plates has some graphics, one of which I'm borrowing here:

_{Graphic by Tom Murphy VII, licensed CC-BY-SA}

(This same sort of image is also used, for unrelated reasons, and with finer circles than the one above, to produce moiré patterns for testing display quality, or for tuning autofocus.)

Versus Pinhole Lens

A zone plate is often compared to a pinhole lens, but there are important differences.

First, it does have a depth of field and therefore can be focused, although usually the DoF is rather large (like using a 35mm lens stopped down to f/22 or so). Second, the amount of light let through is significantly greater. For example, Lensbaby's Pinhole/Zone Plate optic provides an f/177-equivalent pinhole, and in zone plate mode is like f/19 — 6½ stops faster.

This means that with a modern SLR, you can, with care, shoot hand-held. And, although it'll be dark, you can even compose through the viewfinder. (On my Pentax K-7, the metering even works accurately.)

The Look

And perhaps most importantly, the look is quite distinctive. Point sources of light will actually show the concentric-circle pattern of the zone plate in a very dramatic way. And as with bokeh in a lens, this affects the image even in non-highlight areas — areas of bright light have a, well, diffused glow around them. Personally, I don't care for the "archery target" effect of highlights and try to avoid them, but I like the soft look which suffuses the image if point sources are avoided:

_{Photo by me, licensed CC-BY-SA 3.0 at this resolution.}

There's examples on Flickr, and since Lensbaby sells a zone plate optic, they also provide a Gallery of Zone Plate Samples, which nicely illustrates the effect — both the concentric-circle lights, and some more subtle effects as well. I think it works particularly well on flowers and portraits.

Some Zone Plate Options

On the Lensbaby product: I'm not sure I'd spend $100 (or more) for a lens body plus $40 for the pinhole/zone plate optic just for this, but if you already have a Lensbaby, or are thinking of getting one for the other optics, and are interested in this kind of photography, I think it's well worthwhile. Since moving the focus plane and area of sharpness isn't really a consideration here, the Scout lens body might be the best choice, although that is currently only sold with the Fisheye optic.

Pinhole Resource also offers zone plate body caps; at around $65 for the dSLR versions, these are considerably cheaper than the Lensbaby combo (but of course more expensive if you're considering a whole Lensbaby kit anyway). I haven't used these, so I can't meaningfully compare them in practice. I notice that they're f/45 — two and a half stops slower than the Lensbaby. That would probably compromise the ability to compose through the viewfinder, and I wouldn't be surprised if metering is out of the question. And of course it means any portrait subjects need to sit extra-still, perhaps pretending they're getting their 19th-century tintype taken.

And, there's the D.I.Y. zone plate page I mentioned above. This suggests an older process using B&W film to make precise lines, or else simply printing on a transparency with a laser printer. This is probably less precise than the machine-made more-expensive zone plates, which would result in a loss of overall resolving power — but if you're going this approach, resolving power probably isn't your top concern anyway, and as the site notes, you'll have the flexibility to tune your zone plates to different wavelengths of light or to different focal lengths and aperture sizes.

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Can a dSLR be safely made into a pinhole camera?

Question

What exactly is pinhole camera? The wikipedia article says

A pinhole camera is a simple camera without a lens and with a single small aperture — effectively a light-proof box with a small hole in one side. Light from a scene passes through this single point and projects an inverted image on the opposite side of the box.

Can I make my dSLR into one? Is it safe to try this, since there will be no lens? Will the results be interesting?

Answer

Is it safe to try this setup on my DSLR(since there will be no lens), mine is Canon EOS 1000D?

It is possible to make a pinhole from a DSLR. Basically, buy a spare body cap, then make a small hole in its center. Don't destroy the only cap which comes with your camera, you may need it later. Google for "DIY DSLR pinhole" for multiple instructions.

But you should remember that it is still a hole, not a glass, so some dust or liquids may come through it into the camera. On the other hand, when you change lens, even larger quantities of dust may come in.

Dust on the mirror or even on the sensor is not dangerous, but you need to be careful when you clean it later. Dust on the mirror does not affect the quality of the image, but it is visible in the viewfinder, and sooner or later it may reach the sensor. The dust on the sensor is not visible in the viewfinder, but it is visible on the shots with small aperture (large f-number) and, surprise, on pinhole shots. You should not touch the mirror when you clean it, it can be easily scratched; use only a special photographic air bulb to clean it. To clean the sensor you'll need to buy special cleaning kits and have enough patience, but sometimes the air bulb is enough. Sooner or later all photographers have to do it.

Has anyone tried it and got interesting result ?

There is a whole group on Flickr dedicated to Digital Pinhole Photography

An alternative design: a pinhole box.

They also suggest an alternative digital pinhole design in the group description. It is safer, because doesn't require to open the camera and is compatible also with compact cameras:

A ready to use pinhole

If you want to spend some money, you may buy a ready to use pinhole (f/177) from Lensbaby (you'll need to acquire their adapter too) or from other producers (see answers from @Jay Lance Photography and @Stan Rogers).

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