Breaking through a wall...with a mirror

[Michael Tiemann]

I've been wrestling with some wide-angle decisions over the past few days, and came to the conclusion that I'm not really looking for a wide-angle effect...I just want more of the room going into the camera. On a sound stage this is easy--just move the camera back until you get the perspective you want. In a conventional room environment, you are constrained by the four walls (or in my case, six, because the room is hexagonal). It occured to me that I might be able to back up the camera by shooting across a mirror, and for less than $5 I was able to get a super-cheap door mirror (48" x 12") from Wal*Mart to begin investigating the possibilities.

I found that for my application, there are places I can put the mirror that send the image and perspective I want to a place that doesn't appear to conflict with other camera placement requirements, nor does it conflict too much with the function of the room itself. Indeed, I can "step back" about 12' further from my subject than without the mirror, meaning I can be 20' away instead of 8'. More importantly, I can be 13' away from the closest object in the scene rather than merely 1'. If you do the math, the relative size ratio that derives from a distance ratio of 13:20 is much less extreme than a distance ratio 1:8 ! Moreover, I'm really stuck with only one position without the mirror, but with it I can creep forward to get a pleasing mid-point, such as a distance ratio of 5:12.

That's all good...if the mirror is up to the task. The $5 mirror I got from Wal*Mart is not optically flat (nor even optically clean). I see that this company supplies the mirrors used in cooking shows:

And we all know that cooking shows use only the highest possible production values. (I say that only half in jest--some cooking shows really do have great production values, and it's a fact that food finished in 4K tastes much better than film that's only shot in HD.)

I have attempted to search for other references about this technique, but have come up empty. Do any of you have experiences using mirrors to break down walls to get better perspective in your rooms? Are these mirrors really good enough to shoot through/across?

 

[Satsuki Murashige]

If you want a mirror to shoot into, I would recommend finding a front surface mirror. Most consumer mirrors are the rear surface variety, which means they have a sheet of clear glass sandwiched in front. This causes double reflections and some loss of optical quality. A front surface mirror has the reflective surface right up front, which is more fragile and thus less common.

 

[Michael Tiemann]

If you want a mirror to shoot into, I would recommend finding a front surface mirror. Most consumer mirrors are the rear surface variety, which means they have a sheet of clear glass sandwiched in front. This causes double reflections and some loss of optical quality. A front surface mirror has the reflective surface right up front, which is more fragile and thus less common.

Indeed the link I posted above takes you to "optical glassless mirrors" which are front-surface only. They have rigid foam in the back, not only for structural integrity, but it also has beneficial acoustic properties as well. The question remains, is a $2500 front-surface mirror a good investment or a waste of money if the goal is good-looking footage from the "A" camera?

 

[Bob Gundu]

For $2500 I would stick a GH4 up there as a dedicated top view cam.

 

[Michael Tiemann]

For $2500 I would stick a GH4 up there as a dedicated top view cam.

Please remember that the problem I'm trying to solve is one of better perspective. Remember that a GH4 8 feet above those pots is going to show a perspective of every pot extending away from the central vanishing point. By shooting the top view from 32 (?) feet back across a mirror that's 8 feet above the action, you get the nearly orthogonal view that occurs when you are 40 feet away from the subject. The cooking show is not my gig--it's just an example I've found. I'm curious if others have used a mirror to gain better perspective when the space isn't there (or isn't practical to rig) for the straight-on view.

 

[Todd T]

Front Surface Mirrors are the only way to ensure the best optical quality of your scene.

Deciding between Glass or Glassless will be determined by the disadvantages.

Glass is expensive, heavy, fragile and cumbersome to deal with.

Glassless (Tensioned reflective plastic sheeting) will be subject to vibrations. Since you will be on location then Walking around, loud noises, HVAC, or other mechanical systems may induce vibrations.

 

[Michael Tiemann]

Front Surface Mirrors are the only way to ensure the best optical quality of your scene.

Deciding between Glass or Glassless will be determined by the disadvantages.

Glass is expensive, heavy, fragile and cumbersome to deal with.

Glassless (Tensioned reflective plastic sheeting) will be subject to vibrations. Since you will be on location then Walking around, loud noises, HVAC, or other mechanical systems may induce vibrations.

Our location is a recording studio. The floors don't vibrate much when walking around, but loud playback could be a problem. Thanks for the heads up!

 

[Michael Tiemann]

So now I'm looking at this product: http://firstsurfacemirror.com/

Any other suggestions?

 

[ericyoung]

At $2500 a mirror, another issue is how do you keep that front surface mirror spotless and undamaged during a shoot and between shoots?

And most mirrors lose significant light level, which isn't always obvious by eye.

And it can make hiding lights and crew and various set gubbins a pain.

It's definitely a viable tool for a very particular situation. The reason it isn't commonly used is all the issues mentioned above.