Hermagis, objectif pour vues

This lens consists simply of an achromatic doublet, produced by Hermagis, a French optician in business since 1845. It dates probably from 1850’s or 60’s. Its constructive principle is the same of lenses used by Nicéphore Niépce and Louis Daguerre for the very first photographic images. Due to its simplicity and easiness of construction, lenses of this type remained in production for many decades, favored by faster emulsions and popularization of photography in cameras aimed to amateurs.  read more


What can I do with that lens?

Sometimes we ask ourselves things like: from which distance a certain subject would fill the frame of a certain format with a given lens. If in large format photography: What is the bellows extension to get it in focus? What is the exposure compensation? If you ever had that kind of question, and had to go over formulas or guessing games, you have to check out this online simulator. read more… 


Lens front raise online simulator

In some cases, it might be interesting in architecture and urban photography, to keep buildings’ vertical lines parallel in the picture as they are in reality. Well, you know, you can give a lens front raise for that. But will your lens/format have room enough for that? How much can you raise it? Where will the horizon line end up? Check out this online simulator. read more…


Using RAW format in photography

Article analyzes a practical case in which the use of RAW file, thanks to its greater depth of color, allows the exploration of areas of a photograph that in format .jpg would be lost.

Color Depth in digital image files

Systems for producing color images always work from a group of so-called primary colors or components. Other colors are obtained by mixing these primaries. In order to mix them, one must be able to vary the amount with which each one enters the composition of a final color. The primary color group...

Finding the focal length of a lens

  This is a calculator that will help you in finding the focal length of a photographic lens. The method is about focusing on one or more objects at different distances. Each time, you write down 3 measurements: Object size Image size How much did you advance the lens from infinity position in...

Pinhole, where truth, beauty and goodness...

Pinhole is a photographic technique that employs most of the times a home made camera in different degrees of improvisation and roughness. Matchboxes, shoeboxes and whatever boxes and containers are sort of starting point for those projects. The photographer bricoleur may also start from scratch by...

Front raise and horizon line

For a given lens and given film or sensor format, this simulator shows how much it is possible a front raise and where the horizon line will end up in the final picture. Focusing is assumed to be at, or closer to infinity, a normal landscape condition. Observations: 1 – The scheme is...

Refraction, Dispersion and Optical Glass for...

Refraction Refraction is a phenomenon of waves changing direction when passing from one medium to another. In a photographic lens that is the case when passing from air to glass and again from glass to air. It occurs also when passing from one type of glass to a different one. They are not all the...

Lens/subject/format – an online...

How it works: You enter the focal length of your lens, film or digital sensor dimensions and the approximate size of your subject. The simulator shows in value and graphically the following corresponding information: the distance you must place your lens from the subject the image circle and angle...

Ground glass loupe, easy and useful

Quite often we want to check focus more carefully in a view camera . To do that, the obvious idea, goes about using something that enlarges the projected image allowing for more precision than with bare eyes to inspect image’s sharpness. Three problems generally arise when using common loupes...

Immateriality of digital image

It is a fact that the digital image has a state in which it is pure information. That is the case when it is written as a file, as sequence of bits. But once printed in paper, it is no less physical or material than the traditional analog photography. Similarities are not only in this final output...