I'm looking at some clip-in (mirror box) camera body filters. They only seem available for 1.6X crop canon DSLRs, not for Canon full frames, but I'm not sure why.

Anyone know if it's because the mirror is too long as it swings up on full frame, or is there some other incompatability?

(I'm trying to figure out a way to use an interferometric filter with a wide angle lens- behind the lens with a slightly stopped down aperture should get rid of a lot of the problem of off-axis light rays, I think.)

It's entirely possible to produce mirror box filters for FF cameras, like the VAF-5D2 used for anti-aliasing in the Canon 5D MKII.

contact@mosaicengineering.com for more information.

I think that you will find that wide-angle lenses will still vignette using mirror box filters. For a wide-field astrophotography application I recommend multiple bodies, standard lens focal lengths, lens based filters, and overlapping FOVs using a custom bracket and mount. With enough overlap of the images plus staggered intervalometer start times you could probably eliminate your problem with broken star trails too (when the images are combined in Photoshop and using the "Lighten" blending mode.)

Originally Posted by ziggy53 It's entirely possible to produce mirror box filters for FF cameras, like the VAF-5D2 used for anti-aliasing in the Canon 5D MKII. contact@mosaicengineering.com for more information. I think that you will find that wide-angle lenses will still vignette using mirror box filters. For a wide-field astrophotography application I recommend multiple bodies, standard lens focal lengths, lens based filters, and overlapping FOVs using a custom bracket and mount. With enough overlap of the images plus staggered intervalometer start times you could probably eliminate your problem with broken star trails too (when the images are combined in Photoshop and using the "Lighten" blending mode.)

And here I was thinking that a ~$300 broadband light pollution (Hg, Na lines) filter would be a big investment ;)

Thanks for the link, that might be something I could pursue.

A long time ago when I was an Astronomy major I had access to a 9.5" refracting telescope (that's good sized for are refractor). The observatory was in the city, Cleveland, but not when it was built. Another telescope there was used to do spectral analysis.

To calibrate things at one time they had to burn some carbon arc's to get a reference spectrum. As the city crept around the observatory the stopped doing that, instead they just used the sodium lines in the background light from the street lights that were burned into every spectrum they took, as the standard to compare things to.

So look at background radiation as a feature, not an an impediment

Originally Posted by kolibri Alight pollution (Hg, Na lines) filter would be a big investment ;)