Question on focussing on mirrors

Splog

Splog

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Steve
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One for you clever people to work out :D

If you take a photo of an image on a mirror that is reflecting an image of something that would be at infinity if you took the shot directly :) as an example the mirror is reflecting the image of the moon!

Once focussed on the mirror image that is 300mm away would the lens be focussed at infinity or at 300mm ? :thinking:
 
Not quite sure exactly what you're asking! A mirror displays a 'virtual image' which is the same distance behind the mirror as the subject is in front of the mirror.
 
awp said:
Not quite sure exactly what you're asking! A mirror displays a 'virtual image' which is the same distance behind the mirror as the subject is in front of the mirror.
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So that would be at infinity then!

Chaz Photos said:
You will focus at the distance from camera to mirror backing (silver) plus mirror backing to subject
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So that would be at 300mm then!

Hence the question!... Thanks guys....:)
 
I don't quite understand what awp is saying, but ChazP is right - focusing distance is camera to mirror plus mirror to subject, ie infinity in this case.

Also, angle of incidence equals angle of reflectance. So when you see an image of a movie actor in a mirror where they appear to be looking at themselves, what they are actually looking at is the camera.
 
The Matt said:
No it won't. The distance between camera and mirror (300mm) plus the distance between mirror and subject (a good number of miles) is infinity.
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My appologies, missed that bit :bonk: So it's infinity then! Thanks
 
The reflection you see in a mirror is not on the mirror but an equal distance behind the mirror as the subject is in front of it. It is known as a virtual image. That's physics and a fact.
 
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