I understand why a mirror with a projector is used , but what “ is “ and what “ does “ a FS MIRROR do . I can’t seem to find a thread with a simply breakdown.
I’ve seen that to make a fs mirror , you just clean the back of a regular mirror exposing only the mirror element , I got that part.
And I think its only used for DI surfaces - front/rear. And thats all I know so far.
Can anyone take a minute to explain this for me?
Thx Jay.
A FS mirror is better because the reflective side of the mirror is on the front (hence the fs=front side) .. a “normal” mirror has a glass/plexiglass part in front of the mirror (protection?)..
When a beamer hits the mirror in an angle the glass will also reflect give a slightly offset image, the steeper the angle the bigger the offset is.
Causing sort of ghost (double image) effect on your surface your projecting too. That is bad for any kind of projection, this includes FTIR & DI as in both techniques the throw distance of the beamer if often made shorter (well not actually the path to the surface made longer) by using a mirror in this way so that the table can be made less high…
I understand now. thanks.
Now with the angle of the mirror, would you still get an offset even with a regular mirror if its placed at a perfect angle position as I’ve drawn up below?
Without a FS mirror you will always get this effect, how annoying/worse it is depends on t he mirror itself. Some might never notice it or the ghosting will be acceptable. Some will see be annoyed by it
the shorter the total distance of the projector to the screen and the less the angle changes from 90% to the beamer (reflecting image directly back at the beamer) the less you will notice it..
i found that thread in the lumenlab,
explaining how to make your own FS mirror from a regular mirror ,
The technic is to remove the back of the mirror using paint remover (aircraft remover )
Anyone had already try this ?
I’ve tried it, and the result was disastrous. The back of the mirror had a weird color, kinda stained copper like. And it wasn’t nearly as reflective as the front surface.
So, I guess it depends on the mirror. I don’t think it was the paint remover that damaged the reflective layer, because the front surface still looked ok after the process.
I’ve tried this technique, it works out well but i during my testing ive ruined 3 mirrors… you have to be very careful not to scratch your mirror when you are removing the the paint stripper.
I used some spray on stripper, and I scraped it off with a rigid plastic bondo spreader. After letting the stripper soak for a while, I just the spreader at a steep angle and scraped the loose paint off the surface and across the mirror .
I took three applications and the results were better than expected. I have a nice clean unscratched frontside mirror for the $7 that the stripper cost me, and I only used a small amount.
Thank You NUI Forums…
..and Thank You Jay for starting the thread.
I love how this community will eke out when nesessary. This truely is how new things are created or improved. I personally would never have thought to use a standard mirror to make an FS mirror. I would have just looked it up and bought one. Koudos to all.
Now is there any comparison information on the difference with a home jobby fs mirror compared to an actual fs produced one?
The layer build up on a typical mirror is there for a reason and when you remove layers you change the overall effect. On a factory produced fs mirror, bang theres your mirror...perfect. I’m sure theres a difference and hope someone has thought to test the reflective properties of both...somehow.
This seems to be another step , even in a small way to making a better MT table.
Just to add my point of view, a FS mirror isn’t required. I’m using a cheap mirror from a local store (non-fs) at an angle of 45% and do not see any ghosting/double image effect, and that is very sharp on a 1280x720p resolution at a screen of 133x74cm
I think the ‘ghosting’ effect could be related to the quality of the glass, not the mirror reflective surface itself. Even maybe the whole mirror is too thick which could increase the angle of transmission of the light ,or something like that. After reading about some reflective and refraction properties , it seems possible.
Here’s a link to a straight forward explaination of both:
