Category Archives: Tutorials

Effective photography with the ZeroImage 2000 pinhole camera

The extents of the image

What is left that the photographer can use to influence the captured image? Their legs and their arms. By that I mean they can walk around to choose the physical position of the camera and then adjust the direction in which it is pointing. Even this task is complicated by the fact that most pinholes lack any kind of viewfinder capability. Digital pinhole users have the advantage of instant review of captured shots. All is not lost though, as if one knows the film/sensor size and the focal length (pinhole <-> film/sensor distance), it is possible to calculate field of view of the camera using a simple formula

field of view == 2 * arctan (film size / (2 * focal length))

Armed with this knowledge it should be possible to visualize the extents of the scene that the pinhole camera will capture. Indeed the ability to visualize this should be considered essential, if the photographer wants to turn pinhole photography into a reliable tool or art form. Without this knowledge & visualization, the results will be unreasonably influenced by an element of chance. Luck of composition, or lack thereof, is the primary reason why many photographers (incorrectly) consider pinhole photography to produce “crap” results.

For my ZeroImage 2000 pinhole camera with film size of 60mm and focal length of 25mm, the above formula works out to define a field of view of approx 100 degrees. This is just 10 degrees more than a right angle, so an effective way to visualize the extent of the scene when shooting is to stand behind the camera and hold out your arms so they form a little more than a right angle with each other. Each arm will thus point to the left and right borders of the final image. One can imagine drawing/engraving sighting lines on the sides of the camera to allow the horizontal and vertical extents to be more accurately aligned with the desired subject. With this knowledge the photographer has the ability to reliably compose pinhole images, without needing to have any optical view finder or LCD screen preview available.

Of course there is still the question of what part of the scene should be included in the photograph. The 100 degree field of view is roughly equivalent to that seen with a 15-17mm lens on a traditional full-frame 35mm SLR camera. This is very wide indeed and experienced photographers will understand that this has a significant effect on image composition. So much of the scene is included that the main subject can easily end up very small. Somewhat counter-intuitively, the way to deal with a wide angle lens is often to get closer to the subject, much, much, much closer, so you take in less of the scene.

The London Eye is an enormous wheel on the south bank of the Thames. With a 35mm camera it would easily fill the frame with a standard length lens. Using a pinhole camera though, it only fills 1/9th of the frame. To fill the frame the pinhole would need to be at least 2/3rds closer, in the middle of the river! A satisfactory pinhole shot is just not possible from this location.

Instead of positioning the camera 5 meters back from the castle, it was placed on the drawbridge just a meter in front of the gate, pointing skywards. This takes advantage of the wide angle of view to get a dramatic composition.

Instead of positioning the camera 5 meters back from the castle, it was placed on the drawbridge just a meter in front of the gate, pointing somewhat skywards. This takes advantage of the wide angle of view to get a dramatic composition, making the castle gate appear to be a gaping mouth.

The distance to the subject

Consider if we want to entirely fill the frame with the subject. If we make some assumptions about the scene, it is possible to come up with another simple formula to assist us in understanding how close to get. Imagine the camera is positioned such that the film plane is parallel to the plane of the subject, at a height that is half the height of the subject. The distance required to fill the frame with the subject is given by the formula

distance = height of subject / (2 * tan(field of view / 2))

Once again considering the ZeroImage 2000 with a field of view of 100 degrees, the formula shows that to capture a portrait of a person 1m80 cm tall requires the camera to be positioned 75 cm away from the person, at a height of 90 cm. If the field of view were exactly 90 degrees, things would be very simple – the distance would simply always be half the height of the subject. 100 degrees is only a little wider, so we can avoid having to calculate the formula every single by assuming half the height and then moving a little closer.

Now in practice the camera plane may well not be parallel to the plane of the subject – the subject might not even have a single obvious plane to compare against, so it is generally more useful to use the field of view to understand the extents of the image. The distance rule of thumb just helps with understanding the initial rough position you need to walk to, before fine tuning by looking at sighting lines.

By taking into account the distance formula and field of view, it was possible to frame the steam engine so it precisely fills the 6x6 negative without any need for cropping when printing. The curved lines at the bottom are a result of the film not being held completely flat in the camera.

By taking into account the distance formula and field of view, it was possible to frame the steam engine so it precisely fills the 6×6 negative without any need for cropping when printing. The curved lines at the bottom are a result of the film not being held completely flat in the camera.

Playing to the pinhole camera’s strengths

Understanding how to position the camera to capture a subject is all well and good, but before doing that there needs to be some decision about what parts of the scene are desired in the final photograph. Given the inability to control depth of field, to throw distracting backgrounds & foregrounds out of the focus, the decision about what part of the scene to include takes on an even greater importance than with mainstream cameras. Essentially everything from front to back will exhibit the same level of sharpness, so if there is a distracting object in the scene, the camera will have to be physically positioned to try to eliminate or minimise the distraction. With pinholes that have a very wide angle of view, this is harder than it might seem – once again you might find it necessary to move much, much closer to the main subject. Compare the following two images from the same shoot

Ulltraviolet: World Record Cyanotype. The camera is about 2 meters away from the group of people, just 2 foot off the ground and angled pointing down. The cyanotype fills the foreground, but the people in the scene are tiny due to the wide field of view of the ZeroImage 2000. The yellow bins and white crane are also distractions. The result is a fairly unsatisfactory usage of the field of view.

Ulltraviolet: World Record Cyanotype. The camera was no more than 2 foot away from the closest person, just 2 foot off the ground and angled pointing down. This emphasizes the group of people in the foreground, eliminates the boring sky and still captures the entire cyanotype in the background. This is an effective use of the wide field of view.

Wide angles of view have quite dramatic effects on the perception of depth and perspective. Objects that are nearer the lens will be greatly emphasised as compared to those further away. One of the reasons few portraits are taken with wide angle lens is that a portrait taken face on to the person will end up with a greatly exaggerated, and thus unflattering, nose in the centre of the image. This doesn’t mean that you can not use a wide angle for portraits though – one simply has to be aware of this effect and figure out a way to use it as an advantage. For example, positioning the camera an an oblique angle to the person will dramatically increase the distortion across their whole body, making for a much interesting style of image, with no single unflattering point to focus in the centre – the wide spread distortion draws the eye around the image. Similarly when taking architectural shots, the wide angle allows for a composition to emphasize lines in the building.

Kew Bridge Steam Museum. The camera is positioned on the floor underneath the steam engine, pointing directly up. The wide angle of view results in dramatic converging columns.

St Pauls. The camera was placed close to the ground, right up against the wall, pointing almost straight up. This emphasizes the architectural lines and angles in the building and draws the eye into image.

With the tiny pinhole aperture, comes long exposures, which in turn have a big impact on movement. Camera shake is dealt with by using a tripod, or some improvised stand, or a conveniently located surface to hold the camera still. There is little that can be done about movement in the scene itself, once film of a particular ISO has been loaded. Pinholes are thus not usually the right camera for capturing live action sports events. On the flip side though, the long exposure times open up options that other photographers don’t have (unless they have a 10-stop neutral density filter handy). Capturing architectural shots in a busy city requires a lot of patience and/or very early starts to the day if the goal is to eliminate people from the scene. This is no problem for a pinhole camera though – if there are people walking through the scene, they will blur away to nothingness with an exposure of a few seconds. Even with a mere 1 second exposure they’ll be nothing more than ghosts. If there is moving water in the scene, it will blur to a silky smooth carpet, which can provide an interesting contrast to the non-moving areas of the scene which remain relatively sharp with distinct features.

Millennium Bridge. An exposure of about 1 second allowed the people walking across the bridge to blur into ghostly figures. This provides contrast with the man in the centre who had stopped for a photo and so remains relatively distinct

Washing cyanotype. In the 1 second long exposure, the two people washing the cyanotype exhibit movement during the exposure. This provides a enhanced sense of the action taking place in the scene. The eye is also drawn to the second point of interest, the onlooker on the left hand side of the image who is appears sharp in contrast to the two main subjects.

Manufacturers of lenses typically strive to produce glass that results in even illumination across the entire area of the film / sensor, and eliminate flares. Light fall-off in the corners – aka vignetting – is something that they aim to avoid, or at least minimize. With pinholes there is very little that can be done – they will always “suffer” from vignetting, resulting in a prominent hotspot in the centre of the image. This shouldn’t be considered to be a bad thing though – as mentioned earlier, the inability to control the aperture & focal point means there is no scope for using depth of field to de-emphasize distracting details. Given this, the fact that there is a hotspot is actually a benefit as it will draw the eye away from distractions at the edges of the frame. When printing pinhole images it might be desirable to further emphasize the hotspot to take advantage of this effect.

The vignetting effect of the pinhole creates a distinct bright spot in the center of the image. The pinhole also has a dramatic flare effect on the reflection of the sun on the windows which adds interest to the image .

The writing above has barely scratched the surface of challenges and rewards of pinhole photography. There are some very interesting photographers posting to the Flickr ZeroImage photo pool, including a big inspiration of mine, Scott Speck, whose masterful pinhole portraits and architectural compositions I aspire to one day match. It is clear that the best pinhole photographs can match the best from mainstream photography, if a photographer is willing to put in the time to understand and adapt to its unique characteristics. The time owning a ZeroImage 2000 has been a continual learning experience, but since en-graining a mental model of its field of view, the success rate obtained from pinhole shots has increased significantly. The results are no longer dominated by chance, instead an element of predictability has come to the fore. This has provided greater confidence when taking photos, which has in turn allowed greater experimentation with compositions. A return to working in the darkroom, combined with use of the Caffenol-CH-UK developer has also started to form a satisfying personal style across the images when printed.

Planetary astrophotography on a low budget

The Camera (Modification)

There are plenty of video cameras designed explicitly for astrophotography, able to capture either monochrome or full colour images. For a monochrome camera, coloured filters are used to enable separate videos to be recorded for each colour channel. Dedicated astrophotography cameras are at least £100, often much, much more. As a beginner it is hard to know what will be the choice to start with and even whether the interest in astrophotography will stick. The low cost route is to thus go DIY, which involves taking a regular computer webcam and modifying it to make it suitable for astrophotography. There is an enormous selection of USB web cams on sale in the shops, and an even bigger selection second hand on eBay. Some are more suitable for astrophotography than others, so it pays to do a little research on the forums to figure out which have proved effective. Almost every forum thread on the matter will at some point recommend the Philips Toucam, but these are long since discontinued and postings on eBay sell for an unreasonable amount of money.

A little research, suggested that the Microsoft Lifecam Cinema HD is a good contender, and can be had on eBay for as little as £20. This is capable of capturing at a resolution of 1280×720, which is actually higher than many dedicated astrophotography cameras. It is worth pointing out though, that resolution is not king as the individual pixel size, low light sensitivity and noise characteristics all have a huge impact on the end result. The appealing quality of this particular model were the detailed instructions Gary Honis has written about the modifications needed to make it suitable for astrophotography. The images of Jupiter he posted give an indication of what the camera is capable of. Incidentally his website is a fountain of knowledge when it comes to astrophotography camera modifications.

Microsoft Lifecam Cinema HD, as sold

In essence the mod requires stripping off the case to expose the camera assembly and circuit board, followed by very careful surgery to remove the lens and infrared filter, thus exposing the bare CCD chip. Part of the case is then re-attached before fitting it into a 1+1/4″ cylindrical case the same size as a telescope eyepiece. Gary used a pair of eyepiece extension tubes, but the UK company Billet Parts sells a plastic case custom designed & machined for astrophotography mods of the lifecam cinema. If there website shows out of stock just email them and they’ll produce another batch. Highly recommended, as it comes with a dust cap too.

Microsoft Lifecam Cinema HD, modified

One final point is that the CCD chip is sensitive to infrared and the built-in IR filter was removed during the modification. So for doing normal colour imaging of planets, a replacement IR filter will be required. Any standard 1.25″ eyepiece filter can screw into the custom billetparts case, and suitable 1.25″ IR filters can be had for about £20-25 online.

The Capture Phase

With the camera chosen (or built), the first actual step in producing an image is to capture a video. When targetting Jupiter, it is generally recommended that video captures be no more than 2 minutes in length, otherwise features will begin to suffer from motion blur due to its high speed of rotation. If capturing the 3 colour channels separately with a monochrome camera & filters, that means each individual channel is limited to no more than about 40 seconds (and that assumes you have a filter wheel for fast changes). When targetting the Sun or the Moon, it isn’t necessary to worry about rotational speed of the target, so videos can be as long as desired.

For video capture on Linux, the open source program guvcview offers full control over all the camera settings and the video codecs used, which is an important requirement for astrophotography. Maintaining maximum possible detail/quality in the initial video is key to being able to bring out good details in the final image. Critically, transcoding the video from one format to another is to be avoided, as this will usually loose information. The goal is thus to capture in a format that the video stacking application will be able to read directly. The best choice is thus an AVI file, ideally with raw uncompressed codec, or failing that something common like MJPEG. Before going out at night to capture something important, do a quick test capture of 15 seconds and try to load it into the stacking program you intend to use, to verify that it can indeed understand the codec you chose. Using raw uncompressed video results in massive file sizes even for a 60 second capture and may have a lower maximum frame rate; MJPEG is inherently throwing away detail so can compromise the final image quality but allows for higher frame rates. The frame rate is fairly important as the more frames that can be stacked the better the final image will typically be. Pick your poison.

Accurate focusing of the telescope is also a very important factor when capturing the videos. Slight mistakes in focusing can really badly impact the final result. It is worth investing in a focusing aid like a Bahtinov mask for your telescope instead of trying to judge it by eye. While you can make your own, another UK company Morris Engraving produces high quality masks from toughened black acrylic, custom designed for every telescope you’re likely to need, at a very reasonable price on eBay. Again, highly recommended.

Bahtinov Mask

I am using a Celestron Nexstar 4 GT telescope, which is a Maksutov Cassegrain design with 4″ / 102mm diameter lens and 1398mm focal length, giving approx f/13 aperture. The long focal length is quite good for planetary imaging & observing, but makes it fairly poor choice if deepsky imaging is your plan (a fast refractor is a better choice for deepsky). The equivalent model sells new for about £500, but I got mine second hand from a friend for considerably less.

Celestron Nexstar 4 GT

The final piece of equipment is of course a laptop, which presumably most people have access to. Laptops screens are optimized to work in pretty bright ambient conditions, so their screens are correspondingly bright. Upon taking a laptop outside at night it quickly becomes obvious that the screen is far too bright, even on the lowest brightness setting. This totally ruins night vision adaptation and will be very annoying to any other astronomers near by. The solution is to place a piece of red acetate film over the screen which reduces the brightness to a level which does not negatively impact night vision adaptation. Some astronomy shops sell this pre-cut to the size of your laptop screen at vast expense. The secret to getting a deal is to know the word “Rubylith”. Type this into eBay and many vendors will appear offering the perfect material for the purpose. It is also suitable for use as safe-light protection in photographic darkrooms. A sheet for £4.99 was large enough to cover a large laptop, a small netbook, a smartphone and a little left over to make a red light torch.

Rubylith

Summary

To summarize the key pieces of equipment for doing planetary astrophotography on a low budget are

Microsoft Lifecam Cinema HD – £20 from eBay
Lifecam eyepiece adapter case – £16 from Billet Parts
1.25″ IR blocking/cut filter – £20 from eBay or other sources
Bahtinov mask – £15 from Morris Engraving via eBay
Rubylith sheet – £5 via eBay
Laptop – any that can control the webcam.
Telescope with tripod & mount – almost any, but Cassegrains are a good option for Planetary use. £200-300 for a second hand Nexstar 4, or £300-£350 for a brand new Skywatcher 127 which is a real bargain for what it provides – pretty comparable to the Nexstar in what it provides. Or pick from 100’s of other possible scopes.

The setup described above is suitable for imaging The Sun, to capture sunspots, but it is MANDATORY to have a protective filter in front of the telescope. These can be built using a sheet of Baader Astrosolar Safety Film for approx £20. For carrying all the kit around, skip the official cases and adapt a regular sports / holdall bag.

For a selection of the photographs I’ve produced using this setup, browse the ‘lifecamcinema’ tag on my Flickr profile

Caffenol, aka developing B&W film w/ instant coffee

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Peak Imaging is my film processing lab of choice, since they have provided consistently good results and have very fast turn around times. Even if I can send the film off and get it back within 3 days though, that is still 3 days longer than it takes me to see digital photographs. A number of friends develop their own B&W film at home, since you don’t actually need a proper dark room – a small changing bag suffices to transfer the films into the light proof processing tank. I’ve thought about doing this before, but the idea of dealing with lots of chemicals was never too appealing. While researching B&W film processing recently, I happened across an article on a website (I forget which exactly) mentioning that it is possible to develop film using home-brewed developer based on little more than instant coffee. The moment I read about this, I knew I had to try it out for myself.

The science bit

After a little more reading, I’ve learnt that Caffenol developers have 3 key ingredients, each serving a specific purpose.

Instant coffee. This contains a variety of chemicals including caffeine, but the one that is thought relevant to film development is caffeic acid. This is a phenol which acts as the first developing agent reducing the silver halide to metallic silver, revealing an image on the film base.
Washing soda. Photographic developing agents require an alkaline solution to activate them, but coffee is fairly acidic. Washing soda, aka sodium carbonate, acts as the accelerator raising the PH to a suitable level for the developing agent to operate.
Vitamin-C. Caffeic acid on its own will result in very long development times, so the Caffenol-C recipes add ascorbic acid (aka vitamin-C) as a second developing agent to further speed up the reactions.

Reinhold’s basic recipe for these 3 ingredients, Caffenol-C-M, is only suitable for use with film rated at 100 ISO (or lower). It is said to cause fogging of high ISO films during development. I primarily shoot Tri-X 400 in my ZeroImage 2000 pinhole camera, so the slightly more advanced, Caffenol-C-H recipe, was the one to go for – the ‘H’ stands for “High Speed”. This adds a fourth ingredient, Potassium Bromide, which acts as a restrainer to prevent fogging. The minor irritation is that the latter isn’t a common household ingredient. Fortunately Reinhold has since found that Iodized salt can be used in place of Potassium Bromide, and this is fairly easily found in supermarkets.

Getting started

I hadn’t done any film processing at home before, so the first step was to obtain the minimal set of equipment. The Patterson film processing kit is a cost effective way to obtain the core pieces, vs buying them all separately, though searching for second hand items on eBay could probably cut cost even more. In addition, I got the cheapest digital scales that Silverprint stocked and a concertina storage bottle for storing fixer between use.

The recipes linked above need a little tweaking based on the precise ingredients used. In particular washing soda comes in a variety of formulations, anhydrous, monohydrate & decahydrate. Most of the recipes published on the web assume use of the andhyrous (waterfree) formulation, but it is possible to figure out the amount by which to adjust the quantities, by heating in an oven and measuring the weightloss. In the UK the most easily available washing soda is Dri-Pak Soda Crystals, for which people have already verified an adjustment value of x2.7. There isn’t any available data on the amount of caffeic acid in the instant coffees you can get in supermarkets, but fortunately this doesn’t seem to matter much – people have got acceptable results with almost any instant coffee. So don’t waste money on the most expensive brands – pick any old cheap bottle of instant coffee. Pure Vitamin-C powder is available in most pharmacies in the UK, but at stupidly expensive prices. Holland & Barrett have tubs at slightly more reasonable prices, particularly when they have 2-for-1 special offers available. For the final ingredient, iodized salt, the only brand commonly available in UK is Cerebos Extra Fine Iodised Table Salt.

Caffenol-C-H ingredients

Caffenol-C-H-UK Recipe

With all that in mind, the following is a specific recipe derived from Reinhold’s Caffenol-C-H using ingredients available in the UK to make 1 litre of solution. I’m calling this Caffenol-C-H-UK.

150g Dri-Pak Soda Crystals. Cost: £1.00 for 1kg
16g Holland and Barrett Vitamin-C powder. Cost: £6.99 for 170g
40g Sainsbury’s Rich Roast Instant Coffee. Cost: £2.00 for 200g
12g Cerebos Iodized Table Salt. Cost: £0.75 for 400g
water to make 1000ml of solution. Cost: free(-ish)

For a single 35mm film only 300ml of solution is required, so the quantities are

45g soda crystals. Cost: £0.045
4.8g vitamin C. Cost: £0.20
12g coffee. Cost: £0.12
3.6g salt. Cost: £0.006
water to make 300ml of solution
Cost: £0.37 per roll.

while for a single 120mm (medium format) roll film, 600ml of solution is required

90g soda crystals. Cost: £0.09
9.6g vitamin C. Cost: £0.40
24g coffee. Cost: £0.24
7.2g salt. Cost: £0.01
water to make 600ml of solution
Cost: £0.74 per roll

Compared to mail order film processing at about £4-5 per roll of film, or high street processing of as much as £10, Caffenol is very cheap. If you can get cheaper sources of Vitamin-C powder, then the cost will be drop even further. Of course this assumes your time is free too.

Mixing the developer

The critical thing to bear in mind when mixing up caffenol developer is that you are not making soup, rather you are attempting to perform a specific set of chemical reactions. For this reason, it is not advisable to simply mix all the ingredients in one go, instead follow a precise order of mixing.

Fill the measuring cylinder with half the target volume of water from the cold tap. ie if the end goal is 600ml of solution, then fill with 300ml of water
Pour in the soda crystals and stir for a couple of minutes until they are well dissolved. Since Dri-Pak soda crystals are a decahydrate, the temperature of the water will typically drop 8-10 degrees and the volume of solution will increase. NB anhydrous soda crystals would have instead raised the temperature.
Pour in the vitamin C and stir, at the very least until it has stopped fizzing.
Pour in the instant coffee granules and stir for about a minute. The solution will now be a disgusting looking brown sludge :-)
Pour in the the Iodized salt and stir some more.
Top up with further tap water to achieve the final desired volume of solution. The developer is intended to work at 20 C, and mixing in the soda crystals will have lowered it to about 10 C. So when topping up to the final volume, add hot water at first until it is 20 C, then finish topping up with cold tap water.

After everything is thoroughly mixed, allow the developer to stand for 5 minutes to ensure all the desired chemical reactions have completed. If you could not get the temperature to exactly 20 C during the mixing phase, then sit the cylinder in a basin of hot or chilled water as necessary to adjust to 20 C, stirring all the time.

Caffenol mixture

Processing the film

From this point onwards, fairly standard dark room film processing rules apply. Pour the Caffenol into the film tank, turn the stirrer several times and then seal the lid. Invert the tank 3 times and then bang it on the work surface to dislodge any bubbles. The quoted development time from Reinhold’s site is 15 minutes, but for the images produced with my pinhole camera on Tri-X I find 13 minutes gives a better result. I suggest going for 15 minutes at first, and if the result is too high contrast (indicating over development) try reducing it a couple of minutes next time around. During the development time, invert the tank 3 times at the start of each minute.

Caffenol does not require a chemical stop liquid, so when the development time is up, invert the film tank pouring the caffenol down the sink, then rinse multiple times with cold tap water. Keep rinsing until the water is no longer brown, as this minimizes subsequent staining of the fix. Once rinsed, add any regular fix and follow the normal process for that. Since my kitchen has no air extractor fan, I use Fotospeed odourless fix to minimize the fumes. Despite multiple rinses, the fixer will probably still end up stained light brown, but this does not appear to affect its ability to work in any way, so don’t discard it.

Once fixed, a thorough wash is needed. For this fill the tank with water, replace the lid and invert 5 times. Replace the water and then invert it 10 times. Replace the water once more and invert it 20 times. All that remains is to take 600ml of water, add a drop of Kodak PhotoFlo and dip the film squeegee into it. Then pour the water into the film tank, turn with the stirrer stick and invert it once to ensure the film is well coated. Now take the film off the reel, squeegee the water off it and hang it up to dry.

Film drying

For some example images processing with Caffenol, browse images on my new portfolio website

f/138 – Daniel Berrangé

Photography.Art.Astronomy.Science