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Modifications to Canon digital SLR cameras...


The Mods

Controlling and powering your camera

Booking and paying for your mod

Prices and Online Booking

As some of you will be aware, I now live on and work from my boat. I did this to give myself more time to focus on my writing.

See the contact page to confirm the address. If you would like me to confirm, then please email me on

Recommended Mod for Astrophotography.

Astronomiser's rear filter removal modification, which is the prefered mod for astrophotography includes sensor re-alignment with all cameras to allow the auto focus to operate correctly. Astronomiser has now successfully modified over 2500 cameras and images taken with our cameras can be seen in our facebook albums (you do not need to be a facebook member to view these) see Our Facebook albums as well as many other sources. Astronomiser's camera mods are accepted as amongst the best available in the world and we have a long track record of completing high quality modification work to produce images of the highest standards achievable. The prices are very competitive and include return postage.


In recent years, dSLR cameras have been used extensively in astrophotography and the EOS range of digital SLR cameras from Canon have been shown to give impressive results. The only real draw back has been that the fitted filter cuts a large amount of the red light at particular frequencies, giving a very poor response in the crucial Hydrogen Alpha band of emission nebulae.


In general terms, removing or replacing the colour correcting filter in a Canon dSLR increases it's sensitivity to Hydrogen Alpha light by approximately 4 x, allowing upwards of 97% of this light through, where previously only up to 25% of this light passed the colour correcting filter, depending on the camera model. This makes a huge difference in exposure times, e.g., what could be achieved in a twenty minute shot of an emission nebula prior to the mod can be achieved in 5 minutes post mod. The process improves results in astrophotography across the board emission nebulae in galaxies come through more clearly and star colours are more true improving results in all areas of astroimaging.

Astronomiser has years of experience in modifying dSLR cameras with over 1500 cameras modified successfully. We also supply control cables and other products for use with your dSLR. With us, your camera is in safe hands.

Our price includes return postage so all you pay is the price quoted below to benefit from our experience and knowledge in both astro-imaging and modifying all types of dSLR cameras.

A note on the use of EOS Clip filters

Recently, a myth has grown up around the use of EOS clip filters stating that removing the rear filter and replacing it by using a clip filter in front of the mirror will compensate for the change in the optical path allowing sharp focus to be maintained. This is *not accurate* - please read this very short explaination to see why.

A note on the filter arrangement of all current Canon cameras.

All current models of Canon EOS dSLR cameras have two filters in front of the sensor, both are sealed against air or dust flow between the filters. These seals should remain effective after modification.

The one at the front (open to the mirror box) is a UV/IR blocking and anti-aliasing filter - where applicable, this filter also has an integral piezo vibrator for dust removal.

This image shows a sensor of this type with the filters shown separately.

600D Filters

The clear filter in the top right is the front filter - this filter is effectively transparent to the visible spectrum and is suitable for use for astrophotography and allows virtually a full pass for the OIII, SII and Ha lines as well as all other visible light frequencies with a sharp cut off towards the IR and UV ends of the visible spectra (IR and UV cause star-bloating in refractors so for astrophotography it is normally best to remove IR and UV light), meaning that it blocks these frequencies so no other filtering is required when using the camera with a refractor, if this filter alone remains in the camera.

The filter between this and the sensor surface is colour correcting and UV/IR blocking filter that is removed or replaced during modification - it has a blue cast and can be seen bottom left in the above image, still attached to the filter frame. The impact of this filter is to reduce light at the hydrogen alpha band to around 20 to 25% of that which can be detected by a modified camera, meaning that in practice (depending on the camera model), a modified camera is between 4 and 5 times as sensitive to SII and Ha omission lines.


The Mods...

When the rear filter only is removed, the autofocus is no longer as accurate as before the mod so we correct this by adjusting the position of the sensor by the use of smaller shims in fixed sensor cameras and by adjustment of the sensor's position in floating sensor cameras.

There are three types of mod available for dSLRs these are as follows:

Filter removal:

This involves removing the rear colour correcting filter and increases the camera's sensitivity to red light frequencies by between 4 and 5 times, meaning that the amount of Ha response on the sensor post mod for a 5 minute shot is equivalent to between 20 and 25 minutes of exposure before modding. If you intend to use a camera solely for astrophotography, this is the mod you should choose.

Full Spectrum mod:

A full spectrum mod is one where the full electromagnetic spectrum that the sensor is able to detect is allowed through with **NO FILTERING** - the sensor can detect light in far and near infrared and ultraviolet - to allow this full spectrum of light (visible and non-visible light) through, all filters must be removed. A camera modded thusly would require UV and IR filtering for use with anything other than a parabolic mirror system and would only normally be carried out if the photographer wishes to do either IR photography or spectrographic analysis using a diffraction grating.

Focusing post-mod.

The 100D, 500D, 550D, 600D, 650D, 700D, 50D, 60D, 70D, 7D and 5D all have floating sensors. The sensors are marked and the level is measured prior to dis-assembly and every effort is taken to accurately re-position the sensor post-mod, but it is impossible to restore focus as accurately as can be achieved during factory setup.

Restoring the Original White Balance.

Pre mod...

Pre mod shot


Post mod...

Post mod shot


There are three basic methods to restoring a good white balance for normal use post-mod, these are:

Use of an OWB filter several manufacturers supply OWB filters, i.e., Astronomik, that will correct the white balance for normal photography. These are available from general astronomy dealers.

Using a Custom White Balance (CWB) photographing a sheet of white paper and setting this as the white point in the camera by setting a CWB. This works in all non fully automatic functions.

Software Using auto-levels in software will restore a reasonable white balance. Theoretically, you can manually adjust levels to restore white balance in any picture.


Controlling and powering your camera...


Camera Control...

To use your canon camera for Astrophotography you can either just attach it to the back of a scope and use it in manual mode (with a remote) or use software.

Software Control...

In the case of recent models, all of the camera's functions can be controlled using the supplied USB cable, though Astronomiser recomends the use of a serial control cable to correctly utilise 'mirror lock' and for shutter only control using software such as DSLR Shutter.

Other software that controls the full range of camera functions and downloads and displays images are available. These include:

Images can be stacked and processed using software such as Deep Sky Stacker and GIMP.

Powering your camera...

One issue with using a camera for astro-imaging is the constant need to change batteries. Astronomiser produce battery adapters to power your camera from 12v power sources, such as jump starters, car batteries, power stations and bench power supplies.


Booking and paying for your mod...


The cost of this service includes return Special Delivery postage. The normal turn-around time will be three weeks within the UK unless otherwise stated at time of ordering or in the below address notes.

This service can be booked online by simply clicking one of the below buttons and paying by credit or debit card, or by sending your camera with a cheque for the right amount made out to 'Andy Ellis' to the below address. If paying by cheque, please email us to let us know to expect your camera. If you would like to pay by bank transfer, please contact me for details.

Cameras should be sent to my usual address. These will be delivered to me within a week or two meaning that turnaround could be as much as three weeks, though it will more likely be ten days.:

Andy Ellis
19 Candlemass Court,
Mansield Woodhouse,
NG19 9RX

Please ensure that the camera is well packed with plenty of padding (i.e., bubble wrap) and insure the camera for it's full replacement value. In the UK, I recommend Special delivery, internationally, an expedited signed for, insured postal service is essential to guarantee your camera's safety.

Prices and Online Booking...

For earlier models, astronomiser now offers filter removal only which is a full spectrum mod.

For dual filter cameras, rear filter removal and sensor repositioning or full spectrum mods are available.

300D, 350D, 20D or 30D Filter Removal (Full Spectrum Mod). This includes some adjustment to the position of the sensor, but because of the thickess of the filters, it is not possible to accurately restore autofocus. Single Filter Camera Filter Removal 95

400D, 450D, 1000D, 1100D, 40D Rear Filter Removal including sensor repositioning to maintain autofocus. Fixed Sensor Rear Filter Removal

400D, 450D, 1000D, 1100D, 40D Full Spectrum Mod Fixed Sensor Full Spectrum Mod 95

1200D, 100D, 500D, 550D, 600D, 650D, 700D, 750D, 760D, 50D Rear Filter Removal including sensor repositioning to maintain autofocus. Floating Sensor Rear Filter Removal

1200D, 100D, 500D, 550D, 600D, 650D, 700D, 750D, 760D, 50D Full Spectrum Mod Floating Sensor Full Spectrum Mod 95

EOS 60D/70D Filter Removal including sensor repositioning to maintain autofocus. 60D/70DFilterRem 130
EOS 60D/70D Full Spectrum Mod 60D/70DFullSpectrum 130

EOS 7D Filter Removal including sensor repositioning to maintain autofocus. 7DFilterRem 135

EOS 5D MKII Filter Removal including sensor repositioning to maintain autofocus. 5DFilterRem 135

About Payments...


The work will be guaranteed for 3 months after time of delivery against all defects of workmanship - this guarantee is separate from any guarantees you may already have on the camera, and the work carried out will void your Canon guarantee.

If your camera is less than one year old then astronomiser's guarantee is extended to cover all parts and labour for any fault that develops in the camera after modding for three months.

Any damage which occurs during the filter replacement procedure will be communicated to the customer immediately. Although it may slightly add to the expected delivery time, the camera will be returned in the same condition as supplied or better with the modification work carried out.


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