Manoeuvres when using a Petzval type portrait lens

Derogy - Rapide n4 - Petzval typeWith modern lenses it is possible to focus on any part of an image and get a sharp spot while keeping composition as it pleases us. With old lenses, Petzvals for instance, even adjusting the best focus, the peripheral parts of an image will never come out sharp, unless we stop down the lens. This article discusses how to use a large-format camera for situations where the subject we want sharp is far from the optical center of the lens and we want it fully open. read more …


Linhof 23, one camera for whatever kind of photography

The Linhof Super Technika 23 is a medium format camera that combines the features of a rangefinder point & shoot with those of a large format camera with ground glass, film and lens movements. Linhof proposed a lens system and the camera may use film 120 or sheet film in 2¼ x 3¼ ” format. Incredibly creative design and work in fine mechanics.  read more…


William Wray, an English rapid rectilinear

One of the first lenses manufactured by the Englishman William Wray when, in addition to instruments for astronomy, he decided to dedicate himself to photographic lenses. Manufactured around 1885, with serial number 490, it uses diaphragms with five openings selected by means of a rotating disc. Later, Wray would be an important player in promoting the advantages of the today’s universal diaphragm iris system. read more …


Understand focal length, angle of view and image circle

How can a 300mm lens be wide-angle and another 300mm lens be considered long focus? In this article you will learn or review the three basic parameters that define a lens: focal length, angle of view and image circle. You will be able to understand and evaluate the use of any lens for any format.  leia mais…


Bellows project tailor-made for you

Application creates a .pdf for a bellows used on photo cameras of any size. The drawing indicates the cut-and-fold lines in life size. You indicate the measures, pay via Pay Pal and receive the project by email within a few minutes.

Using a Petzval lens for potraits

Using Petzval-type lenses for portraits when the subject's face is out of the center of the image requires some care. The article discusses and gives an example of how to decentralize the lens to reposition its optical axis over more peripheral areas of the photographic frame.

Mix your formulas – black and white...

Find a compact set of chemical reagents, 8 in total, that will allow you to develop film and print B&W photographies. With instructions about mixing, using and cost considerations. A nice starting point if you are interested in setting up a photography darkroom and make your own chemicals.

Enlarger head using LEDs

Article presents project to build a black and white photo enlarger head, with timer, using LEDs and Arduino platform. The result is high power and excellent contrast control for black and white work.

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

Article explains why and how color-depth concept is necessary to express the array of different colors a digital system can handle. It clarifies why it must be expressed in bits, what that means in terms of color differentiation, when true-color is reached and why sometimes more than true color...

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...