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[OmerBaram]

Hi everyone,

I’m in the process of modifying my Nikon D800 for astrophotography and planning to replace the internal low-pass/hot mirror filter with one that allows better transmission of H-alpha while still blocking UV and IR light.

I understand that maintaining the exact original thickness of the internal filter is crucial to preserve correct infinity focus, especially when using Nikon F-mount DSLR lenses.

So far, I’ve found references suggesting that the original hot mirror in the D800 is between 1.1 mm and 1.3 mm thick. I also heard someone measured the filter in a D70 and found it to be 1.5 mm, but I’m aware this may not be the same as in the D800.

My questions:

1. Does anyone know the exact thickness (in millimeters) of the D800's original internal hot mirror filter?


2. Has anyone here replaced it successfully with a 1.1 / 1.3 / 1.5 mm replacement and maintained good infinity focus with Nikon lenses?


Any confirmed measurements or suggestions would be greatly appreciated. I'm trying to avoid having to recalibrate lenses or shift the sensor if the thickness is wrong.

Thanks in advance!