NIKON F3, modified for the U.S. NAVY

[Akira]

Very intriguing images, Ron!  Thanks for sharing.

I suspect that glass fiber plate is used as relay optics (like some Polaloid backs) which lowers the contrast.  The yellow filter might be used to recover the contrast?

[RonVol]

Very intriguing images, Ron!  Thanks for sharing.

I suspect that glass fiber plate is used as relay optics (like some Polaloid backs) which lowers the contrast.  The yellow filter might be used to recover the contrast?

You're welcome Akira, glad you enjoy them 
I'm not sure what you mean by the "glass fiber plate".
I know what you mean by the optical-fibre relay used in those backs.
This attachment doesn't utilise that kind of system.
It seems that the yellow filter is in fact used for what you say, to enhance the contrast.

[JohnBrew]

Back in the days when I raced enduro karts (60's - 70's) we used yellow eye shields on our helmets when it was cloudy or overcast. They really sucked in the light and made it much easier to see.