Archive | January 2014

Fuji X100: the Pitch Black project (infrared and beyond the infinite)

x100-overview

In the corner of my office, there is a small cabinet full of old Persol sunglasses, almost all of which have Havana Brown frames and bottle-brown tempered glass lenses. They are brilliant for photography because that shade of brown makes everything look so beautiful, and it takes a lot more than the metal eyepiece of a camera to scratch glass. The problem is that virtually all of them are now derelict, with cracked frames, missing lenses (dropping onto cement causes tempered glass to shatter into a million blunt cubes), and general acetate decay.

I worried for a little while that my Fuji X100 would eventually meet this same fate, slipping bit by bit out of use until it became a paperweight or a bludgeon-style weapon for a small child to use. So I wondered, “why not make it see something I can’t?” And so the project began to build a full-spectrum X100 (UV + visible light + infrared). It’s a little like eyeshine in Pitch Black, the rather interesting indie movie that spawned the awful Riddick sequels.

Here are some examples of what the X100 can do with its intrinsic IR capability, a Polaroid 720nm filter (like a Hoya RM72), and difficult-to-handhold exposures (as in things like 1/10 sec at f/2 at ISO 3200 – which would not be too bad if you were used to using infrared film back in the day.

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Standard landscape, shadow side, unmodified camera.

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Standard landscape, lit side, unmodified camera.

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Backlit tortoise-shell Persol glasses, unmodified camera.

The X100 actually turned out to be the best camera for a conversion for a number of reasons:

  • It has live view for focusing and a glass viewfinder for framing. This solves almost every focusing and framing problem that plagues the conversion of DSLRs. You can’t really do a full-spectrum DSLR because sticking an infrared filter on the lens blocks the viewing and focusing mechnism. And putting a filter on the sensor not only limits your options – it also means that your phase-detect focus can only be optimized for visible or IR – not both.
  • It can be fitted with 49mm filters. Pretty much every bandpass filter ever made comes in this size.
  • It has a color balance fine-tuning facility that works on the red-magenta axis. This is important because it helps cut down on the number and strength of filters used to shoot visible light.
  • Its conventional Bayer pattern and files are supported by a considerable number of platforms, and some are coming down the pipeline (like Accuraw Monochrome) that will be able to do uninterpolated conversions.
  • It is a very small camera with a very big sensor.

The filter pack. The X100 has a package of filters that sits right in front of its APS-C sensor. These consist of a UV/IR blocking filter (interference type), two layers of filters that act as the antialiasing filter, and a thin sheet of S8612 filter glass, a bluish rare-earth glass filter that knocks out the rest of the UV and IR. Most cameras have a package like this, usually adhered to the sensor.

To convert a camera to infrared only, you pick your wavelength, usually 590, 650, 720, 830nm, etc. and install the appropriate filter. The lower the number, the more visible light gets in. More visible light means that you can differentiate colors better, leading to something called “false color.” At around 830nm, something really magic happens, and everything goes monochrome (well, at least mostly; see below). It does this because the R-G-B (or Bayer) filter on the sensor does not work at all with infrared light – it all goes right through. On film cameras, there was no infrared conversion – you would put some infrared film in and slap an infrared filter over the lens. That led to a very low-performance arrangement: focusing had to be adjusted, the film picked up a very large range of light (an “infrared” filter usually started well into the visible light range, so not everything could be focused perfectly), and so things always looked a little soft. With a closed-loop focusing system on a digital camera, you don’t have to stop down – and the advent of cheap filters 830nm and up, it is easier to concentrate only on IR light.

To convert a camera to full spectrum involves replacing the filter pack with a piece of colorless glass. Shot without a filter, this leads to a reddish picture – because you have dropped a cyan filter from inside the camera and because there is significant infrared contamination in the red channel. So for visible light shots, you need to stick something on the front of the lens to block everything but the visible. Your basic choices are (and they are by no means mutually exclusive, since the X100 can use two full-size filters with no vignetting):

  • Interference filter: the X100 has a 35mm FOV (@35mm), which means that you can use a B+W 486 filter with no color shift. The 486 knocks out pretty much all UV and all IR. It cannot be used on wider-angled lenses. The 486 is not actually a bad idea with any camera; it does not screw up color balance and it kills the remaining IR bleed (the X100 attenuates IR 10 stops, but that’s still an amount you might want to cut).
  • BG38, BG39, or S8612: these can be in many instances the only solution you need – they knock out most IR, a tiny bit of UV, and re-compensate the color balance of the camera. The problem is that these filters are made of fluorite glass impregnated with rare earth metals, which gives you fragility (or scratchability) combined with vulnerability to moisture (Schott publishes warnings with all of them that they will decay over time). To do a really good job, you also need to block UV.

It is of some note that if you can get away without an aqua filter, then you pick up some sensitivity in the red and green channels – meaning that if you are shooting b/w, you might get a speed boost.

Filters. The big complaint about full-spectrum cameras is that you always have to use filters. This is not such a big deal if you are like me and use a B+W MRC UV to seal off the end of the X100 lens tube anyway. And certainly, you are not cabined to a camera that shoots one band of IR and has zero ability to shoot normal pictures. This is more of a consideration when you start talking about more expensive cameras.

Should you go with an IR-only camera? On an SLR camera, the answer is probably yes, because you can’t slap an IR filter on the lens and still be able to see through the viewfinder (the filter would be behind the mirror and not in your line of sight). Additionally, an SLR can’t be set up to autofocus both IR and visible light (the focus points are different). The downside on an SLR done like this is that the metering is usually in the viewfinder, so you are not metering through the IR filter.  The other thing to consider is that, contrary to some statements you have seen on the interwebs, slapping an 830nm filter over a 720nm conversion is not the same as just using the 830nm (due in part to the fact that you have to multiply the transmission curves).

The conversion. The camera went to LDP LLC (MaxMax), an outfit in New Jersey that has a pretty impressive array of optical conversion services, almost like the armorer in The Man with the Golden Gun (Bond: “Of course, yet you make guns for fingerless hoodlums, bullets for assassins…”). Why LDP? The simple reason is cleanliness. I saw the dust test from another service that converted X100s, an I was not impressed. The other thing is turnaround; LDP gets your camera back within a week.  And indeed, the camera arrived there on a Thursday and shipped out on the following Monday. The conversion was more expensive than the $450 shown on the website; it was actually even more than the $500 someone reported paying for an X-Pro.

The conversion did not change anything visibly on the camera except a tiny amount of stress on some of the leatherette. Here are some preliminary observations (and some sample shots will come with the next installment).

General exposure: with 720nm and 830nm (B+W 093) filters, there is little predicting where exposures will end up (unless you pay very close attention to whether CFL bulbs are the light source – they emit very little usable light). The 720nm filters generally expose similarly to the uncoverted camera. That points to absolutely huge sensitivity to IR in the CMOS sensor, since you are basically lighting an entire scens with wavelengths that humans can’t even see. At 830, you lose about two stops in most situations that involve sunlight or incandescent light. Fluorescent lights produce very little IR, and exposure times rise radically.

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093 filter, hot lights

Color. You’ll obviously want to pick a pleasing color balance, but this is where you land with the various permutations as they show in auto white balance and with some tuning:

  • No filter – big red cast
  • No filter (cyan +9, blue +4 to +9): reasonably good auto white balance; blue “wood” effect.
  • 720nm (no trim): pink or blue to white. Many woods and some plastics look blue.
  • 720nm (cyan +9): neutral plus blue.
  • 830nm – monochrome red-violet to white. Don’t worry about false color; just put the camera in black and white mode or convert to b/w in Lightroom.

The AWB on the camera will generally get you to a place where for 720nm, things will look like Frankie Avalon in heaven in Grease. Strike that in part. The clothes look like Gene Kelly’s suit in Xanadu. Faces still render fairly normally; some synthetics look pinkish or bluish. Wood looks blue. With 830nm, it’s monochrome purple (easy to turn to grey).

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AWB for hot lights (720nm). Note the ghosting that occurs – lens multicoating is ineffective in IR light.

You can, of course, do what you want with false color to suit your mood.

720nm, false color

720nm, false color

Monochromaticism. There seems to be a little bit of misinformation about monochromatic operation in infrared. You hear that in the high infrared range, Bayer filters become transparent. With the 093 filter, which may be as far as you want to go to shoot available light, the apparent effect is monochromatic in files, but a dump of the raw file using the Unix command-line program dcraw (use the -d flag) reveals that the various channels are not exposing exactly evenly.* Accuraw Monochrome promises to fix this and prevent the false noise that occurs.

*Why are all off-the-shelf OS X builds of dcraw so old that they can’t do the X100 (let alone the X-Pro1)? To get dcraw to work, you need to install xCode (1.72Gb plus) and then do a recompile. Getting xCode for a machine with OS 10.7 or earlier is a lot like pulling teeth. I will see if I can’t find a way to make this build available. That said, dcraw does not do a great job with 093 to monochrome conversions, particularly at high ISOs.

Take for example Mr. Spats (the insets are at 200%, so you can see the effect more clearly).

Overall view, made mono in Lightroom

Overall view, made mono in Lightroom

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Detailed view, LR conversion (200%)

Straight dcraw conversion (200%)

Straight dcraw conversion (200%)

dcraw RAW dump (200%)

dcraw RAW dump (200%)

Cautions for social photography. IR photography has two uses that are interesting. One is landscapes, where you can help cut some haze and get more dramatic skies and plant tones. The other is for available-light social photography, where people’s faces light up much more brightly in IR than they do visibly (I have no idea why this is; my guess is that ceiling mounted can lights, even when apparently dim, can emit a lot of IR radiation that we just can’t see).  Aside from that, there are many practical observations about taking pictures of your friends.

  • Red-eye is fierce when you use IR and flash. Everyone is a Replicant, and Lightroom does not see the red-eye to correct.
  • IR pictures without flash can sometimes give “doll eyes,” depending on the iris color.
  • Be careful with some clothes that go from black to white; nothing becomes see-through, but you can see undershirt lines and the shadows of other bulges that you wouldn’t notice on a black background.
  • At 720nm, it’s very easy to spot where people have hit the Just for Men or the Clairol hair coloring products because they come out in unusual colors (most hair and some skin looks blue, but there is a hyper blue from the dyes). For some reason, dyed hair has a distinctive signature. I need to do more testing to confirm this.
  • Note that the X100’s focus assist lamp does not transmit any usable focusing assistance for 830nm and up filters.
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The icy effect of rebalanced 720nm. Or is that the cold shoulder? This shows you how you can get quite a bit of usable light in environments where you can barely see.

And another. Here is some fierce IR lens flare.

And another. Here is some fierce IR lens flare.

Not for X-Ray. There seem to be some pervs who think that infrared is great for “see-through” effects. Let me offer some observations on this:

  • If your goal is pornographic, there are many better ways to spend $550.
  • Most people wear more than one layer of clothing.
  • Forget about fabrics – most materials in general are not sufficiently IR porous to allow light to go in one way, bounce off something underneath, and then make it back to the camera. That “fake check” thing is very hard to reproduce.
  • I’m sure you can teach to the test by going outside in massively strong sunlight and make an attack on the thinnest, chintziest synthetics, but most synthetic materials actually reflect IR brightly, to the point that black becomes bright white.

My suspicion is that wherever these effects do exist, it’s at wavelengths that are very difficult to shoot anyway (950nm and up).

Upshot. This is still under heavy testing, but on balance, the better low-light capabilities of a converted camera are fun – and open up some doors you might nor otherwise see. That said, where the camera has a lot of IR capability already, you may be better off living with the longer exposures (or getting a tripod). We’ll update over the next few months.  The issues currently under study are false noise (or high ISO noise, as the case might be) and ways to improve 830nm focusing operation.  But it’s been fun so far.

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Twelve filters for digital: what’s hot and what’s not

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B+W 491 redhancer

Hot

  1. B+W 010 MRC – pretty much the highest-quality protective filter that exists, the B+W MRC resists flare, dust, liquids, and fingerprints. This can be swapped out for a KR1.5, though the tone difference is so small as to be negligible. The newer Nano versions repel water even better, but probably not as much as their 40% premium would suggest. If your primary goal is killing UV haze in the mountains, the fabulously expensive B+W 415 is a better choice. It has only a single coating and no water repellent characteristics, but it has pretty much the highest UV blocking power you can get without a color cast.
  2. B+W 491 Redhancer (2x) – as far as red enhancing filters go, this is the real deal. Using the same Corning glass as Howard Ross did when he invented the enhancing filter, this one selectively cuts alternative colors, which makes reds, yellows and oranges stand out from each other. It has a flat suppressive effect elsewhere. This is not a filter whose effect can readily be replicated using Photoshop, but sadly, it is becoming extinct. You can still get the less impressive versions from Hoya, Marumi, or Tiffen. A couple of cautions that might make you think twice about making this “the new UV.” One is that rare-earth glass often suffers from humidity damage (corrosion). The other is that it does not block very much UV light.
  3. 80A/KB15 (2.2x) – automatic white balance has not rendered the tungsten correction filter obsolete – because incandescent light is deficient in blue – and blue is the noisiest channel when amplified. If you are shooting this filter in room light and balancing with a flash, be sure the gel the flash with an 85 to make it the same color as the room lights.

Warm

  1. Infrared filters (720nm) (~1,024x) – Infrared was a real pain back in the day. But most digital cameras have so much infrared contamination that when a 720nm filter is screwed on, they expose just like old-school infrared film (as in barely shootable without a tripod on a bright day). These filters work the best on contrast-detect AF cameras that automatically compensate for focus shift. You can get a 560 or 650nm filter for “false color,” but they focus less precisely – and the result may be mistaken for a Japan Air Lines travel poster featuring cherry blossoms. An 800nm+ is an option for true monochrome IR, but it is difficult to focus.
  2. B+W 486 UV/IR cut (1x) – this oddball interference filter is most often associated with the Leica M8. It has coatings that  cleanly kill UV (at least as well as a UV filter) and IR.  “Infrared,” you ask, “isn’t that filtration built into the camera?” Yes and no. Digital cameras attentuate IR light but do not completely eliminate it. That’s why you can screw a 720nm filter onto an unconverted camera and (barely) shoot a daylight picture with it. Further, camera AF systems are not aided by IR contamination in the red channel. The catch? You can’t use it on lenses wider than 35mm field-of-view.
  3. FL-D  – the rise of compact fluorescents is reason to revisit these filters that kill the sickly greenish glow. If only they made a version for LED light bulbs. Soon, my children, soon.
  4. Cokin these filters can be uncontrollably cheesy. But for an average price of five bucks apiece on the used market, you can have a lot of fun without cracking open your post-processing software or doing the same retrofilters as the fauxtographers you look down on. Mirrorless cameras are quite easy to use with them. If your taste is more conservative, Cokin has a decent selection of good grad filters, two-color polarizers, and other landscape staples.

Cold

  1. ND8x – unless you are shooting an f/2.8 lens, most modern cameras that go as low as 200 ISO can shoot wide-open in sunlight. Some cameras now have ND filters built-in (c.f. Fuji X100/X100s).
  2. Circular Polarizers – circular polarizers are needed only when you are metering through a semitransparent mirror. If you don’t have a DSLR, you can get away with a linear polarizer from the junk bin at your local camera store. That said, the need for any type of polarizer is usually exaggerated. If you want to experiment with polarizers, start with the junk bin at your camera store.
  3. Diffusers – soft-focused pictures are good for the 1980s, but that was 30 years ago. But they’re still perfectly good for nudes with perms.
  4. Round graduated ND filters – grad filters are already endangered by Lightroom. Use them if you don’t like computers. But if you don’t like computers, why shoot digital? And round graduated filters are inflexible (you can’t move the “horizon,” which can be pretty critical).
  5. Clear digital filters – why do these exist? Why not just an UV and get something out of that extra flare?

Tenba P415: a rereleased, slightly decontented classic

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Front view

Note: this discussion starts with the P415 originally released in 1985 (and is based on an example purchased in 2003). The re-introduced P415  (released December 2013) has some changes as noted.

If we are going to discuss a camera bag, let’s at least talk about what makes a good camera bag in general:

  • It holds what you need to hold in a way that lets you pull out an individual item without disrupting (or dumping out) other items.
  • Its design does not make it hard to insert or remove items. For example, a bag whose opening is noticeably smaller than its “floor” makes it necessary to twist the item around to insert or remove it in the case.
  • It does not threaten contact between your equipment and metal zippers, hooks or snaps that might unnecessarily damage your camera.
  • It does not accelerate wear and tear on your equipment through contact with other items.

These considerations are why the Platonic form of a camera bag is a padded fabric box with padded dividers. a top flap that exposes all the contents to access, and a shoulder strap. The Domke F-803 is an excellent exemplar, and it is the direct competitor to the Tenba P-415 that is the subject of this article.

Styling. It is a bit ironic that this is described as a “briefcase,” except that it is what a P415 came to resemble given developments in other luggage. In 1985, men generally did not use shoulder-strap briefcases; they used handle briefcases. When this came out, it would have more resembled a tote bag or a carry-on overnight bag. Only in the mid-2000s did this come to look like a laptop computer bag or a shoulder-strap briefcase. Styling is extremely conservative; it’s just black ballistic nylon with black straps and black leather tags (to Tenba’s credit, they are simply embossed and not inscribed in bright colors). Lining is a smooth grey nylon fabric. Most zipper pulls are rubber-coated.

Carrying. This bag has two carry modes. It can be carried by a handle on the top (the top flap must be latched) or by a shoulder strap with a comfortable pad. If you want the strap to go away completely, you can zip it into the gusset used for expansion (so obviously, this is not an option when the bag is “expanded.” The original version of this bag could take optional backpack straps (these anchored at two rings in the lower rear corners of the bag and two under the handle). The backpack strap accessory and its connection points are now history. Although there is a near-universal tendency to label bags like this as “courier” or “messenger” bags, they are in fact shoulder bags. Real courier or messenger bags are more specifically designed to be stable on your back wile biking or hiking.

Main compartment. Tenba says this “holds a DSLR with a battery grip, an attached 70-200 f/2.8 lens, two additional lenses and a flash inside.” This really needs some revision and/or explanation. First, if you are using the supplied PI-13 insert (the bag has no bottom padding) and have not expanded the bag, this will barely fit a camera like a base D700/800 (no MB-D10) plus a long lens. The picture below is more indicative of the actual capacity; note that the shoe-mount flash is the entire width of the insert. In the default configuration, try to avoid thinking that this is a battleship DSLR bag – because it is not. The padded insert/dividers are not stiff enough to drop a DSLR in “nose down.” All of that said, this is a good fit for small DSLRs, mirrorless or rangefinder systems, and small medium-format cameras.

P415 open, showing actual capacity when not expanded.

P415 open, showing actual capacity when not expanded.

The main pocket has a nylon septum in the front and back that separate the padded insert from the padded sidewalls. Though originally designed for magazines or writing pads, these are actually the ideal places to stick a laptop (in “expanded mode” the bag can take a big-screen Dell e6420), netbook, or tablet.

Opening the expansion zipper allows the main compartment to expand a couple of inches front to back, and this also gives you a couple inches left and right of the padded insert. This is quite useful; you can stick a shaving kit and some clothes (or a brick of 120 film) in the extra left-to-right space.

The front organizer is accessible by undoing a wraparound zipper. This organizer varies between the two versions of the case (old and new). This picture is the new one:

P415-interior

Hump pockets: On both versions, there are two humps on the front section of the bag that are just padding; the humps have two side zippers that allow you to access two items the size of a Sekonic L-358 meter.

Key hook: On both versions, this a very handy feature when traveling.

Mesh pockets: Both versions have one mesh pocket on the front (flap) and back of the organizer. These were designed to hold 35mm film cans, but today they hold lens pens, Speck Grabbers, SD cards, small cords, etc. For scale, the mesh on the front part holds two Gepe waterproof SD card cases (6 cards total); the rear holds three (9 cards total).

Pen pockets: The old version has two, on the left as you look at the open organizer from the front. The new version has two on each side.

Padded internal pockets: this where the design changed significantly. On the original, between the front “hump” pockets (shown above with a red thing in one and a filter case in the other), there is a single pocket that holds 5 rolls of 120 film. On the new version, here are two smaller ones. On the rear side of the organizer, the old version had two equally-sized padded pockets (holding 7 rolls of 120 or an equivalent-sized object like a paperback book, Walkman… er, portable hard drive), one with a velcro flap over it. The new vesion omits the flap and includes more pen pockets. The flap is actually useful for restraining wound-up cords that want to un-wind.

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This is the somewhat dodgy “tablet” pocket.

Tablet pocket: be very careful. The P415 has a full-width, zip pocket between the slot for a roll-on bag and the main bag. This pocket is not a great place to put tablets because it is (a) near the outside of the bag; (b) easy for others to get into; and (c) vulnerable to impact from the handle of your roll-on bag. The old version of the P415 also had a zipper pocket inside the zipper pocket – and that metal zipper pull would scratch the hell out of a tablet. Leave this one to magazines/boarding passes and stick your tablet in the internal area discussed above.

Attachment point for roll-on bags: one useful thing about this bag is that you can slip it over the extended handle of your roll-on bag. The bad news is that when the P415 is loaded, the 2″ of webbing for the attachment, even with the snap closed, is not always enough to prevent the bag from swinging backward. More modern bags have a handle attachment point that runs most (if not all) if the height of the bag, providing more stability.

Strengths in use: Usually, a camera bag is something else trying to be a camera bag. The P415, by contrast, is a camera bag that is capable of serving other purposes, such as being an overnight bag.  Extended, it can take a shaving kit and extra clothes, in addition to a decent amount of photo gear. My P415 has done yeoman’s duty in Europe, Africa, Asia and South America. The zippers and connectors are well thought-out and quiet. The only velcro on the modern version is in the umbrella loop, top handle (why does this separate at all?) and the interal dividers. The original has only one additional velcro point, the covered organizer pocket. The fabric has proven to be almost indestructible (as “ballistic nylon”probably should be), and the foam has now held up for more than a decade. The leather parts are a little dry, but none of them have any relationship to the function of the bag. The design in general has aged well. Although it was designed in an era where laptops did not exist, where cameras were big, and imaging was limited by how much film you could carry, the spaces in the bag are still usable for modern photo appliances.

Weaknesses in use: The P415 has the typical vices of the open-top shoulder bag and exactly the same ones as the Domke F-803: there is an open space between the top of the bag and the flap over it. This allows faster access to equipment without dragging painted objects over zippers – but it also allows small objects to fall out if you are not careful. That this is in any way water repellent would be an overstatement. The nylon will repel rain for a short time, but within about 20 minutes, water will start making its way into the top cover. It will be quite a while before that moisture gets to your equipment, though. It is still a lot more effective than any form of canvas. The multiplicity of pockets can also get you; I thought I had lost a NEX-5 charger and battery in New York; it surfaced in one of the crevices of the bag right after the return period for the replacement was up… Finally, the only thing to have failed, long-term, is the pull on the zipper that operates the expansion figure. It’s not expensive to repair, but the YKK zipper pull was easily bent.

Upshot: the P415 is a good counterpoint to Domke hair-shirters and the over-designed, under-functional flavor of the week from San Francisco. In its way, it is minimally designed (no flaccid water bottle nets, no stripes, no modular attachment points) and maximally functional, without presenting many pickpocketing opportunities (or enticements). There are a lot worse ways to spend the $169 MSRP on a bag. I can think of few better ones.