It is possible to modify any Canon EOS body to use it for IR or astro photography by exchanging the default IR cut-off and low-pass filter in front of the sensor. The removal of the original filter is basically enough to achieve the enhanced IR sensitivity needed for astro or IR photography, but will result in AF failure (inaccuracy), non-working sensor cleaning mechanisms and in higher risk to damage the sensor surface during maintenance. Also dust on the sensor will have greater impact on picture quality. This method might be enough, if you are going to use the modified body exclusively for astro photography (no AF needed) while using one of the dust protection bayonet inserts available. But it will also be possible to still use a modified body for normal daytime photography as well, if you not just remove but replace the original sensor filter with plain optical glass or special filters suited for IR or astro photography. The use of a modified camera in artificial or daylight conditions only requires additional filters to restore original functionality. It is possible to convert a camera on your own, but it's a risky approach and replacement filters are still not for free. Below is a list of companies offering professional conversion services.
Astrodon [link] is a trademark offering DIY replacement filter sets. They do not offer conversion service, but have distributors all over the planet, some of which do offer conversions using Astrodon filters. Filters are available for Canon EOS 300D, 350D, 10D, 20D, 30D [#AD300D], EOS 1000D, 400D, 450D, 500D, 550D, 600D, 40D, 50D, 60D, 7D [#AD40D] and for EOS 5D Mark II [#AD5DM2]. They advice to just use a custom white balance setting for normal daylight photography after modification.
Astronomik [link] is a collaborative project of Astro-Shop and Gerd Neumann jr. offering filters with very high durability and quality. They give a 5 years warranty on these.
Besides sensor filters their catalog includes the EOS Clip-Filters, which mount in the lens bayonet to keep dust out of the camera body and can easily be dismounted. It allows EF lenses as well as mount adapters to mount in the bayonet. Only EF-S lenses with their longer rear part are not compatible. As of 2011 there are 18 different kinds of clip filters available (clear glass, H-Alpha, UHC, IR, UV-IR-cut-off, OWB (for daylight photography after modification) etc.). Compatible Canon EOS models are 1000D - 1100D, 300D - 600D, 20D - 60D and 7D. EOS D30/60, 10D, 5D series and 1D/1Ds series are not compatible. Especially for those they still offer the T2 filter holders, that screw into a T2 mount and take a T2 lens on the front side.
Astro-Shop as well as Gerd Neumann jr. both offer camera conversions for the compatible cameras mentioned above, as well as converted brand new cameras (Neumann currently lists the 550D and 1000D, Astro-Shop lists the EOS 1100D). Special: Astro-Shop claims to not void warranty rights on preconverted cameras, you get a full warranty here.
Baader Planetarium [link] is a company located in Germany that offers a sensor filter conversion service as well as their own filter sets for DIY application. Both are available for all digital Canon EOS bodies except D30/D60 and EOS 1D/1Ds series. You can order brand new cameras with modification here as well, but of course at the cost of Canon warranty loss.
Baader also offer lenses for astro photography under the Scopos brand. Scopos is a joint project of Baader and Teleskop-Service.de focusing on cost effective imports from Far East.
A recent model is the Scopos ED APO 66/400 refractor, making a 400mm F6.0 lens if mounted to a DSLR via optional T2 adapter system. The lenses are available in black/chrome or black/bronze with a weight of 1800g, featuring a retractable lens hood and tripod collar. Overall length is 300mm.
An older model also mountable to a DSLR was the Scopos Observer 80/480, making a 480mm F6.0 achromatic lens (mounted via TS-FA2 T2 focus adapter). The lens comes in black with a tripod collar, a weight of 2400g and 380mm length. This model is discontinued as of 2011 with few samples left in stock.
One of the accessories available here are the T2 & M48 Protective T-Rings for Canon EOS w.2" & 50.8mm Filter Compartment. Similar to the Astronomik Clip Filters they are installed into the body's lens mount, take protective filters as well as color or IR cut-off filters and thus protect the body from being entered by dust particles. T mount lenses can directly be mounted.
CentralDS [link] is a company from South Korea offering total conversions of EOS cameras including peltier deep cooling (compare JTW Astronomy below). The cameras are completely stripped off their cases and placed into custom CNC'd aluminum housings. They are remote controlled using a PC or MAC running BackyardEOS. The Canon EF mount is reduced to a dumb mount (Canon E-M lenses won't work!), and a 2" nose for telescopes is included in the package. The following models have been/are available:
CDS-1100D (2012): 12V 3.6A peltier, 138 x 85 x 78mm, 970g
CDS-600D (2012): 12V 3.6A peltier, 138 x 85 x 78mm, 970g, remote control port for RS60-E3 optional
According to the manual (1100D + 600D) only AV, TV and P modes are available. Although specifying a temperature of 28°C below ambient, it is also stated that sensor temps will reach -36°C (±2°C, without to mention required ambient temps). The 2" nose provides an internal 48mm filter thread and from the description it also sounds like there is another 48mm holder built into the camera to mount filters when using EF lenses or alike.
The units require an external power source. Maximum cooling is reached 7½ mins after power-up.
CDS-5D (EOS 5D Mark III, 2013): two stage peltier cooling at 12V 4A down to 38°C below ambient, only B mode is available, 165 x 165 x 104mm, 1550g
The above CDS series goes back to only 2012. CentralDS has a longer history in providing the Astro series of Canon modifications using external cooling modules with sensor cold fingers (again the JTW IceCubes work the same way) and spectrum enhanced UV/IR blocking filters. With this modification the built-in flash (where available) and self-cleaning functions are sacrificed, but the cooling units - ExCoolers - installed side-by-side to the camera provide pass-through ports for wired remote control and USB. All ExCoolers provide realtime temperature monitoring via LCD (i.e. 60D req. 2x LR44) and fan speed regulator.
Astro 60D (2011): non-removable ExCooler installed at the rear (where usually the LCD would fold in), 12V 3.6A, 26°C (±2°C) below ambient, 1100g
Astro 5D Mark II (2011): detachable ExCooler F50a installed at to the bottom, 12V 4.2A, 28°C (±2°C) below ambient, 1530g, comes with Hoya clear filter by default - enhanced UV/IR filter is optional
DSLR Astro Mod [link] UK based conversion service offering Astronomik L-Clip and Baader system modifications.
DSLR Astro Tec [link] is based in Germany offering Baader filter modifications for all Canon DSLRs excluding D30/D60 and 1D/1Ds series. You can also send them your camera along with your self-purchased filters of whatever brand for conversion.
Geoptik [link] from Italy as of 01.2015 is the last company to still sell DSLR cooling boxes - in their case called the Polar Photo Box (2011). Similar boxes were also sold by Orion called the DSLR Camera Cooler (~2012) and by Starworks called Cooling Box MK1 (USA 2009). The boxes are designed like underwater housings and externally cooled by a Peltier element with a fan mounted on it, which looks pretty much like a simple CPU cooler. The claimed cooling delta temperature of Geoptik is 20° and the unit needs 30mins of operation to reach it. Compatibility is commited to Canon EOS 350D, 400D, 450D, 500D, 550D, 1000D and 1100D. The box features an LCD to display the internal temperature.
The boxes are discussed with lots of critical examinations among astro photographers. One thing is the efficiency. Since the DSLR is put into the case in its original state its own housing works like another isolation against the cooling box (cold air outside, hot sensor inside), which decreases the effective sensor cooling ability of these boxes to only a few degrees. Condensation seems to be a serious problem as well [source]. All this, together with the simple construction and the high pricing for the off the shelf boxes (between 200 and 400€) lead to a lot of DIY projects accomplishing similar effects.
Hutech [link] is based in California offering the usual sensor filter modifications for astro (H-alpha enhanced bandpass), scientific (clear filter) and specialty imaging (no filter), but they also add a screw-in-filter holder in the camera's bayonet for use of low-profile 37mm filters. The cameras cannot be used with Canon EF-S lenses. AF functionality is retained, sensor self-cleaning available in astro and scientific modifications only.
JTW Astronomy [link] is based in the Netherlands. JTW now do not just offer the usual sensor filter removal, Baader replacement or debayering, but also a total conversion including peltier deep cooling. What you get with the total conversion is a unit looking like a retro styled micro fridge, with a heatsink on the back and lens mount on the front - and nothing else but a USB and DC port on it. The units are completely remote controlled using BackyardEOS (included in the package). Thanks to the deep cooling, long time exposures at even high ISO values are possible without the usually occuring amount of noise. Camera housings can be color annodized (any color - any pattern) and engraved to the specifications of the customer. From Feb. 2014 on JTW cameras come filled with Argon 4.6 (the units are sealed using o-rings). The following generations have been released:
Ultimate V1 (2011): air cooled peltier, 30°C below ambient, came with decent cooling ribs on its back
Ultimate V1 Pro: as above, just cooling down to 45°C below ambient temps
Among the choice of new camera models were EOS 1000D, 450D, 550D, 600D and 5D. Custom conversions of any used EOS possible.
Ultimate V2 (2012): air cooled peltier (1 heatsink), sensor T at -15°C (constant), cooling ribs were gone, 12 screw heads on the back
Ultimate V2 Pro: air cooled (2 heatsinks, sensor T at -25°C (constant)) or water cooled peltier, both 150W
Although based on Canon EOS these early conversions had infinity focusing issues with at least some EF lenses due to the housing's thickness.
The cameras featured the JTW mount, which allowed to mount various telescopes and lenses via adapters (T2 and 2" included, Nikon and Canon optional).
Among the choice of new camera models were the 1100D, 550D, 600D and 5D Mark II. Custom conversions of any used EOS possible.
Ultimate V3 Deep Cooled (2013): air cooled two stage 70W peltier, sensor T at -30°C, maximum cooling reached ~5¼ mins after power-up, low-pass filter removed, color and monochrom (debayered) versions available, 4 screw heads on the back, exchangeable dumb Canon EF mount being the default of the early makes (Canon E-M lenses won't work!), electronic mount (a.k.a. lens drive) was in the works ('beta') as of 10.2013 and soon to be widely released (delivered with all later makes of the V3 cameras); the later conversions also already feature the PWM setpoint cooling units;
stock models have been/are:
EOS 1100D [#ULT-1100D] (2013): 155 x 105 x 90mm, 900g
EOS 600D [#ULT-600D] (2013): 155 x 105 x 90mm, 900g
EOS 700D [#ULT-700D] (2014): 155 x 105 x 90mm, 900g, already feat. PWM setpoint cooling and lens drive throughout all makes
Ultimate Client Assembly Kit (2014): an idiot-proof DIY kit with detailed instructions to do the conversion at home (consequently DIY conversions won't necessarily be filled with Argon); fits all APS-C sized Canons
custom conversions of any used EOS are possible except for the 7D, which turned out not to be suitable for conversion for not properly providing bulb mode out of M via Backyard (noted back in 11.2012, then also valid for the 60D, which was indeed convertable a year later)
Ultimate V3 Eco: low powered versions of V3 DC (40W and 60W systems)
Seemingly due to some lag in information transmission the Eco is usually referred to as V2. Still it's a V3 - same housing like their Deep Cooled equivalents and even the younger model of the two. Due to further enhancements of the V3 Deep Cooled series by matters of power management and efficiency the Eco series was abandoned in 2014.
Ultimate V4: feat. PWM setpoint cooling - now fully controllable via computer, the lens drive and JTW's own scientific grade BBAR coated IR filter;
EOS 1200D [#ULT-1200D] (2015): 155 x 105 x 90mm, 900g
EOS 700D [#ULT-700D] (2015): 155 x 105 x 90mm, 900g
For those on a tight budget and/or 'wrong' camera model JTW also offer the IceCube - an external cold finger type CMOS cooler with a single stage 30W peltier element, offering delta temps of -15°C to -20°C (depending on your camera model).
Version I (2012) looked like a cube and was either installed to the side (might block the remote control port) or to the bottom of the camera (blocks the tripod socket). Those IceCubes could be fitted to any camera model just by using dedicated cold fingers. Once installed, the units were non-removable (attached using epoxy). Installation was possible DIY or as factory service.
Version II (2013/14) looks and mounts similar to a battery grip - even adds a DC power option to the camera. It comes with advanced cooling control (adjustable temperature with digital readout) and offers passive cooling as well.
Random fact: The company name derives from the initials of its founder's grandfather - John Trevor Woodward.
LDP LLC [link] a.k.a. MaxMax.com offer several kinds of camera conversions including such exotic stuff like vegetation stress glass replacement. They have modified brand new cameras in stock as well as their own brand of XNite filters. Conversions are offered for EOS 60D, 10D - 60D, 300D - 600D, 1000D -1100D , 7D, 1Ds Mark II, 5D and 5D Mark II. They also offer IR modified flashes (Canon Speedlite 580EX and Sunpak 622).
Life Pixel [link] is an american company offering DIY sensor filter sets as well as repair and conversion services (including lens adjustment btw.). The conversion service includes all digital EOS models ever produced, with the exception of the 1D Mark I - IV (1Ds series is listed though). Their homepage is full of articles about basic knowledge, sample photographies and even detailed tutorials for DIY conversions.
Optik Makario [link] is another german company offering a range of conversion services. They use their own filters. The conversion service includes all digital EOS models ever produced.
Primaluce Lab [link] caught some attention during 2016. They offer a Canon EOS 700DA Cooled [PLL700DAC], which looks a lot like early JTW mods with a huge double peltier cooling unit attached to the back of the camera, where usually the LCD would swing in. Still the display is preserved and swings to the side of the cooling unit. Sensor temperatures are kept as low as -30°C below ambient temperature. A display on the back of the unit shows the actual temperature, indicates the efficiency of the integrated anti-dewing system for the sensor filter and cooling fan speed. It also allows to set prefered values for default sensor temperature, anti-dewing system efficiency and fan speed. The anti-dewing system works by heating the sensor filters' surface. PLL recommends to use their EF-T2 adapter with an 50.8mm filter in its integrated holder to completely seal the camera body for use in high humidity environments. The cooling unit is powered by a 12V 5A DC power supply unit and provides a 7.4V DC output to power the camera as well (corresponding cable required). Last but not least the cooling unit also incorporated a shutter control system (requires extra wiring to the camera's remote port as well) which allows to set a number of images to record (1 to 50) at exposure times of 1, 5, 10, 30, 60, 120, 180, 300, 600 or 900 seconds. Optional gimmicks further include a shockproof hardshell case. Weight of the camera is specified at 1100g.
Spencer's Camera & Photo [link] is another american company offering conversion services as well as converted brand new cameras out of stock (again Canon warranty is lost, but they give a 6 months warranty themselves on the cameras). The conversion service includes all digital EOS models ever produced. Spencers developed a special sensor heat reduction system to minimize digital noise during long time exposures, which fits most Canon EOS models.