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Would you use IR/ UV cut filter with a cooled ccd osc?


lensman57
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Hi,

The title says it all, the resaon I ask is that I have been told that using such a filter with a cooled CCD OSC will drastically reduce the cameras sensitivity, it came about about in a conversation with someone whom had made a decision not to instal an Ir/uv cut on the production of cooled ccd cameras. I can only assume he knew what he was talking about but I find it difficult to digest.

Regards,

A.G

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ccd's are sensative to the IR but if you do not want to capture IR then you would have to filter it out. From the description I guess it cuts IR and UV so leaving the visible band, around 400-700nM, and it will attenuate that to some degree. Would not expect more then 20-30% attenuation, so 80% transmission say.

If you have a refractor then you probably have to use an IR filter as the IR will in effect be out of focus to the visible and this "blurred IR image" would appear on the ccd output image.

I expect that narrow band R, G, B filters block IR and UV and that aspect of imaging is not exactly uncommon.

Edited by ronin
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ccd's are sensative to the IR but if you do not want to capture IR then you would have to filter it out. From the description I guess it cuts IR and UV so leaving the visible band, around 400-700nM, and it will attenuate that to some degree. Would not expect more then 20-30% attenuation, so 80% transmission say.

If you have a refractor then you probably have to use an IR filter as the IR will in effect be out of focus to the visible and this "blurred IR image" would appear on the ccd output image.

I expect that narrow band R, G, B filters block IR and UV and that aspect of imaging is not exactly uncommon.

Thank you for your reply,

The point was raised while discussing the merits of a popular ED doublet (FPL 53 Glass) V a well corrected triplet Apo, I got the impression that the triplet in question would focus the IR and thererfore filtering it was not necessary, I may however have got the wrong end of the stick.

Regards,

A.G

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