Correcting Prism for Daguerreotype Cameras. c.1840s - early 1850s

The daguerreotype image correcting prism shown in this post is an accessory I’ve been trying to find and acquire for decades. It’s rare. Nearly all collecting colleagues have never seen an example. In fact, it’s so obscure that a Google search only produces comments about these accessories. Nearly all remarks, however, are copied from other posts. No pictures or detailed descriptions and information. Even though the reversed image problem was widely documented since the 1839 invention of photography, for some reason these accessories are described conceptually. Maybe this is due to their limited practical use and advertising.

A few of my early photography ephemera mention prisms and mirrors but rarely have illustrations or product details. A well-known collector once told me: “The thing is so rare that even its shadow is collectable.” Actually, he was referring to my Argus 12-Shot Repeating Camera (posted here on Show & Tell), but in my opinion his comment also applies here.

As a note, prisms were available for later process and copy cameras, but this post is about true Daguerreian era accessories made from 1839 to the early 1850s. I also contacted the George Eastman Museum (GEM) Technology Curator. The GEM collection has a couple mirrors and Todd (the Curator) kindly shared pictures. To fix this historical oversight, I am researching these curious accessories and the variety of ingenious methods invented to laterally correct images in camera or afterward. My intent is to write a paper.

So, here is a sneak peek of a dag era correcting prism mounted on a historically correct camera.

As background, several years ago I posted a small, cased daguerreotype image which started an informative Show & Tell conversation about why dags and tintypes are laterally reversed left-to-right (flopped). For example, signs on buildings are backwards. I made a second post that includes a picture (from a white-paper) of an 1842 French daguerreotype camera with correcting mirror and summarized the concept. I also mentioned knowing of only two sold over a period of decades and a desire to acquire one for my collection.

Recently, a collector and good friend mentioned having a Daguerreian prism and wondered if I was interested. He knew I was attracted to his other daguerreotype accessories. I saw a couple cell phone pics, paid his asking price and now have it in my collection.

The correcting prism is well made, heavy and deeply patinaed. The silvered portion of the prism is nearly perfect because it is protected by the brass enclosure. In contrast, correcting mirrors have front silvered surfaces. Unfortunately, front silvered mirrors are exposed to the environment and easily tarnish. Cleaning is a delicate process.

I was able to make a crude adapting ring for the prism assembly and fit onto the lens hood of my c.1850 American Chamfered daguerreotype camera. Once mounted, I learned why these are practically non-existent. I discovered new challenges of aligning and composing. It is counterintuitive to years of normal camera operation. The image also darkens slightly which means exposures need to be a little longer.

In a nutshell, correcting prisms and mirrors are a challenge and my belief is very few photographers tolerated the complications. The public eventually accepted flopped dag and tintype portraits because it was the same as looking in a mirror. Daguerre, inventor of the daguerreotype, also admitted to not using correcting accessories. Regardless, a few intrepid daguerreotypists used prisms and mirrors. Otherwise, these represent an interesting footnote in the evolution of photography.