A single lens reflex camera is by far the most suitable type to use.Its versatility allows eyepiece adaptors and magnifiers to be fitted,and some allow you to replace the standard viewfinder and/or focusing screen with others more suitable for microscope work.You can either use the camera lense to photograph the image produced by the microscope,or you can attach the camera body (without lens) directly to the microscope.
If you use the camera lens always focus the microscope image first,and use the camera lense set on infinity.When the camera is positioned above the microscope at the point of focus of the microscope image,the picture will be in focus.You can find this point by moving the camera up and down until the image in the viewfinder is sharp.
If you use the camera body only, you focus through the camera viewfinder by adjusting the focusing knobs on the microscope.When the image in the viewfinder is in focus,your picture will be sharp.By using only the microscope optics
in this way you minimize distortions which can be exaggerated by the camera lens.This enables you to produce high-quality photomicrographs.
SUPPORTING THE CAMERA
It is impossible to hand-hold the camera over your microscope eyepiece.You need a means of securing the camera in the position.such as an enlarger column ( without the enlarger head ),a table-top tripod, or a copying stand.
Many SLR manufacturers supply microscope adaptors which enable you to fix the camera in the correct position. The camera body,with an extension tube attached, is connected to an adaptor ring around the microscope eyepiece.
An ever better idea is to support the camera and adaptor independently of the microscope. Using a heavy, rigidstand minimizes the possibility of vibration being transmitted from the camera to the microscope. When your are photographing at such large magnifications ( much larger than life-size ) even slight vibration results in blurred pictures. If you use this system, you must prevent light from reaching the film expert through the camera shutter.You can make a light trap by using two lens hoods or two tubes of black opaque card which slot one inside the other.
FILM
Special photomicrography films are made, but they tend to be more expensive than ordinary film and your local dealer may be reluctant to place a small order.You can achieve good results with a medium contrast, fine grain film. The speed of the film regulates grain size, and for first-class photomicrographs choose a sloe film to enable sharp, fine detail to be rocorded. Films like Kodak Panatomic X and Ilford Pan F are suitable black and white negative films.For colourful subjects use a colour side film ( such as Kodachrome 25 ) or a colour negative film ( such as Agfacolour CNS ).
Colour Balance: if you use colour slide film for ypur photomicrographs make sure your match it to the light source.You can use tungsten balanced film with tungsten lamps (3400K ).If the light source does not match the film use the appropriate colour conversion filter between light source and subject.
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PHOTOGRAPHY
Friday, 22 April 2011
PHOTOGRAPHY THROUGH A MICROSCOPE
Taking photograph through a microscope is called photomicrography .It is not beyond the capabilities of most photographers, provided their interest is great enough and their working methods are careful and accurate .There is certainly no shortage of subject matter .You can find suitable specimen in the kitchen and garden, or indeed almost anywhere you look. For successful pictures through the microscope you need three basic pieces of equipment: a microscope, a light source and camera.
Microscope
For you first experiments in photomicrography there is nom need to spend a fortune on acquiring a superb instrument unless you really want to even low priced models are adequate .Before committing yourself to a purchase perhaps you can arrange to borrow a microscope from a friend, or from a school or college during the vacations, or to hire one from a reputable dealer .This way you can find out what suits you best ,and if you interest is deep enough to buy equipment of your own. The simplest type of microscope consists of the following basic parts: eyepiece, tube, objective, stage, sub-stage condenser, light source.
Eyepiece
At the top of the microscope is the eyepiece which allows you to view the microscope image. For photomicrography you must use a “flat field” eyepiece to eliminate fuzzy edges which would occur with ordinary eyepiece. Choose one or two with magnifying powers around x6 and x8.
Tube
The tube is simply a piece of cylindrical metal which separates the eyepiece from the objective. The tube length is not unlike the focal length classification of a camera lens.
Objective
The microscope lens. The objectives are often sold separately from the microscope. You need on or two objectives to begin with. Magnifying powers of between x5 (five time magnification) and x20 (20 time) all give interesting views of simple structures. The most common objectives are called “achromats”. These are the least expensive type and are perfectly adequate for the beginner .If and when your interest deepens there will be time enough four you to invest in more expensive objectives with greater correction of image distortions.
Lighting
To produce a good photomicrograph you need a good light source. What ever source you choose it should be bright enough to allow reasonably short exposure times. A 100W tungsten lamp is a suitable light source for black and white pictures. For colour slides you might prefer to use a photographic lamp (colour temperature 3400K) to ensure correct colour reproduction with tungsten balanced film. Special microscope lamps are also available. They usually have an iris diaphragm which can be adjusted to control the size of a light beam. Although you may have limited success by using daylight ,its colour quality and brightness are variable. You would not be able to take pictures in the evening, and the unreliability and unpredictability of daylight causes problems. You would find it difficult to estimate exposures in different weather conditions, and colour reproduction will vary. Flash is consistent in quality and can be useful when you are photographing living, moving specimens and want to freeze the motion. But unless you can adapt the flash head to fit a modelling light inside it you will find it difficult to judge the lighting effect.
Stage
The stage is a platform on which the subject is held firmly in position(by clips) at right angels to the objective. The subject is a microscopic specimen mounted on a small glass oblong called a microscope slide. The stage has a central hole to allow light to pass through from below.
Sub-stage condenser
A system of lenses below the stage which focus light intensely on the subject.
Light source
Only more expensive models have a lamp built in below the stage. Simple microscopes use a swivelling mirror under the stage to reflect light up through the subject and into the objective. The mirror is often double-sided-flat( or plane) on one side concave on the other .It can be swivelled to select either surface.
http://www.pstutorialspro.com
Microscope
For you first experiments in photomicrography there is nom need to spend a fortune on acquiring a superb instrument unless you really want to even low priced models are adequate .Before committing yourself to a purchase perhaps you can arrange to borrow a microscope from a friend, or from a school or college during the vacations, or to hire one from a reputable dealer .This way you can find out what suits you best ,and if you interest is deep enough to buy equipment of your own. The simplest type of microscope consists of the following basic parts: eyepiece, tube, objective, stage, sub-stage condenser, light source.
Eyepiece
At the top of the microscope is the eyepiece which allows you to view the microscope image. For photomicrography you must use a “flat field” eyepiece to eliminate fuzzy edges which would occur with ordinary eyepiece. Choose one or two with magnifying powers around x6 and x8.
Tube
The tube is simply a piece of cylindrical metal which separates the eyepiece from the objective. The tube length is not unlike the focal length classification of a camera lens.
Objective
The microscope lens. The objectives are often sold separately from the microscope. You need on or two objectives to begin with. Magnifying powers of between x5 (five time magnification) and x20 (20 time) all give interesting views of simple structures. The most common objectives are called “achromats”. These are the least expensive type and are perfectly adequate for the beginner .If and when your interest deepens there will be time enough four you to invest in more expensive objectives with greater correction of image distortions.
Lighting
To produce a good photomicrograph you need a good light source. What ever source you choose it should be bright enough to allow reasonably short exposure times. A 100W tungsten lamp is a suitable light source for black and white pictures. For colour slides you might prefer to use a photographic lamp (colour temperature 3400K) to ensure correct colour reproduction with tungsten balanced film. Special microscope lamps are also available. They usually have an iris diaphragm which can be adjusted to control the size of a light beam. Although you may have limited success by using daylight ,its colour quality and brightness are variable. You would not be able to take pictures in the evening, and the unreliability and unpredictability of daylight causes problems. You would find it difficult to estimate exposures in different weather conditions, and colour reproduction will vary. Flash is consistent in quality and can be useful when you are photographing living, moving specimens and want to freeze the motion. But unless you can adapt the flash head to fit a modelling light inside it you will find it difficult to judge the lighting effect.
Stage
The stage is a platform on which the subject is held firmly in position(by clips) at right angels to the objective. The subject is a microscopic specimen mounted on a small glass oblong called a microscope slide. The stage has a central hole to allow light to pass through from below.
Sub-stage condenser
A system of lenses below the stage which focus light intensely on the subject.
Light source
Only more expensive models have a lamp built in below the stage. Simple microscopes use a swivelling mirror under the stage to reflect light up through the subject and into the objective. The mirror is often double-sided-flat( or plane) on one side concave on the other .It can be swivelled to select either surface.
http://www.pstutorialspro.com
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