A Manual of the Collodion Photographic Process - Photographic Lens

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Contents

• Preface
• Introduction

Part 1

• Collodion Process
• Preparation of the Gun Cotton
• Preparation of Collodion
• Iodizing of Collodion

Part 2

• Preparation of Collodion Film
• Immersion of Plate in the Bath
• Exposure of the Prepared Plate to the Action of Light
• Development of the Image
• Fixing of the Image

PART III

• The Whitening Process
• The Camera
• Description of the Camera
• Glass Bath
• Photographic Lens
• Summary of Precautions
• Conclusion

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Photographic Lens

The amateur will find a good lens an indis- pensable item in his catalogue of photographic requirements. He can have either a single lens for a landscape, or a double combination, where rapidity of action is required, as is the case with a portrait.

The use of a lens combination of less than 7 inches or 8 inches focal length should be avoided ; for the distortion attending the image formed by a lens of shorter focus than this, will interfere very much with the truthfulness and correct proportions of the picture. With a very short focal length, the relative size of the objects in a picture is rapidly increased or diminished, when they are removed but slight distances from any particular plane: consequently, a combination of lenses of less focal length than that named above, should not be used.

For some time past I have devoted much attention to the construction of Fluid Lenses, in which the necessity of the flint glass lens is done away with, by the use of a fluid of such density and refractive power as will achromatize and correct the curvature of the crown or plate glass lens.

I have succeeded in the construction of such combinations, and can produce them of great power and flatness of field.

With them what are called the chemical and visual focii perfectly coincide; they do not therefore require the slightest adjustment in regard to these two difficulties.

I have used no other kind of lens for many years.