What is the difference between ACF and BCF Filters?


Question: I am interested in the conversion of a Canon 400D / 40D. On their websites you can only find the filter curves and description for the ACF filter, not the BCF filter used for this conversion! What are the differences in the daylight suitability if it is not simply identical with the ACF filter?

Also I noticed that the ACF filter from 1100nm is permeable. Is this a problem?

Answer: The CMOS chips of the EOS series behave like most other chips from different manufacturers, they are from 1050nm rapidly insensitive to light. Therefore, it is pointless to continue to block past 1100nm.

The effect of the BCF filter corresponds exactly to the curve shown on the website! We do not want to publish the design details of how we achieve these spectral characteristics, so there is no graph for the BCF filter, but rather a comparison of the filter effect on the 400D / 40D with or without the Baader BCF filter.

With regards to daylight suitability there are virtually no differences. In terms of hue, overall dynamics and anti-aliasing there are some small drawbacks, although completely suitable for private use a second housing is recommended for professional application. The astronomic optimised filter increases in other areas in Astro recordings such as sensitivity and sharpness.

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