Mirror in Auto RB Graflex 4x5 camera - back-silvered?!

[blee1996]

Hi,

I have an older Auto RB Graflex 4x5 SLR camera (with longer bellows, interchangeable lens board, drop bed, and front rise) whose mirror seems to be "back-silvered" with a dimension of height 127mm, long end 118mm, short end 90mm. I have not taken out the mirror so I do not know the thickness.

Is it normal or factory original to have a back-silvered mirror instead of front-silvered mirror for this older version of Auto RB Graflex 4x5? The mirror is in very good condition, is it could be a later replacement that might be installed the wrong way?

Thanks!

 

[Hunter_Compton]

Yes, originally rear surface mirrors were used in the Graflex SLR cameras. This was done because mirror coating technology had not yet advanced enough to make a durable front surface coating.

To the best of my recollection, the change to front surface occurred in the mid-1930s.

You can change to a front surface mirror if you need to replace it, but you will need to re-shim the ground glass further away from the mirror to ensure the plane of focus stays the same.

 

[blee1996]

Yes, originally rear surface mirrors were used in the Graflex SLR cameras. This was done because mirror coating technology had not yet advanced enough to make a durable front surface coating.

To the best of my recollection, the change to front surface occurred in the mid-1930s.

You can change to a front surface mirror if you need to replace it, but you will need to re-shim the ground glass further away from the mirror to ensure the plane of focus stays the same.

Thanks for the information. Since the mirror is in good condition, I will just leave it as is and get focus calibrated on the ground glass.