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Terry Lovejoy | profile | all galleries >> DSLR's For Astrophotography - Tech Notes >> 'Improving' the 300D for Astro tree view | thumbnails

'Improving' the 300D for Astro

It is possible to modify the 300D to greatly enhance its sensitivity to astronomical objects (see spectral response tests and pre mod/post mod examples). This involves removal of the standard IR cut/AA filter. It is not that hard to do but does require some previous experience working with small electronics (estimated modification time ~2-20 hours). Even with these skills there is a risk that the camera may be damaged/destroyed during the modifcation - so don't blame me!

The first inspiration for this modification came from this site http://www.seo-e.co.jp/hobby.htm

Also, some considerations for daylight photography. In particular:

Sensitivity : There is a useful 0.5 stop improvement is sensitivity

White Balance : White Balance needs to be adjusted as well as the colour profile at the red point of the colour 'gamut'. Custom White Balance does an OK job at adjusting this, but I feel the best option is to use an external blue-green filter to match the existing Canon Filter.

Autofocus : Can be fixed with a substitute optical filter in place of the existing Canon IR/AA filter. I used a Baader UV/IR block filter replacement which only absorbs light outside the visual spectrum, for details see the Baader website. Ideally this filter will be the same thickness, but chances are this will not be possible (as is the case with the Baader), so adjustment to the packing under the CMOS sensor will be required. For a thinner filter the sensor needs to be moved 1/3 the difference in the filter thickness. There is also some small adjustment available in the autofocus screw.

AA Filter : With the AA (anti-aliasing) filter removed images are very sharp. On the downside 'jaggies' and 'moire' become apparent in some situations. This will not however be a problem for most graphics packages. You may actually prefer the sharper images over the standard camera.

I have a mini-procedure for doing this mod here.

Standard Filter
Standard Filter
Blue Channel
Blue Channel
Green Channel
Green Channel
Red Channel
Red Channel
Filter Replacement
Filter Replacement
Procedure for Modifying the 300D for Astro
:: Procedure for Modifying the 300D for Astro ::
CCD Up Close
CCD Up Close
Spectral Response of DSLR Cameras Compared
Spectral Response of DSLR Cameras Compared

comment on this gallery
From: DaveC Date: 19-Jul-2004 08:32

An alternative to using the baader filter...
Edmunds optical makes a 3mm thick optically transparent, anti-reflective coated, filter grade glass. of course you still need a ir cut filter but that can be placed anywhere in the optical train.
the part number is NT32-741.

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