Camera types
35mm SLRs versus Digital. Most quality SLRs can be fitted to a microscope with adaptors sold by the manufacturer. A few, such as Olympus, provide additional screens for their cameras to aid focusing when used with a microscope or telescope. Many digital cameras can be fitted to a microscope by adaptors sold by companies such as Anglia Leps
Most digital cameras provide easy video output, which allows you to see things on a TV, very useful for focusing.
An advantage of digital is the immediacy of the images, allowing you to re-shoot if necessary, and the ability to enhance those images on a computer. Slow shutter speeds will make the use of a cable/remote release essential.

This is a huge and varied subject; the below information is based on my own experience but other people’s ideas and tips would be welcome. It is assumed that most people will be working with a limited budget!

Microscope types
Stereo dissecting microscope. This is a must for dissecting. For photographic purposes, they offer better depth of field and an ‘upright’ image. In other fields they are outclassed by even modest compound microscopes. Some SDMs come with an in-built digital camera.
Compound Microscope. These tend to have lighting systems and lens arrangements which yield finer detail. They have poor depth of field and the image is upside down. Some CMs come with an in-built digital camera.

Technical Aspects
Lighting. SDMs are usually fitted with lamp situated below a ground glass or opaque plastic stage. The transparency of this stage affects the visibility of fine detail. Heavily opaque stages will scatter light and mask fine detail. Viewing fine detail may seem like a good thing, but not always: If you are trying to clearly see the shape of the valves only, the appearance of unnecessary detail can be distracting (see examples). In addition to the lamp CMs usually have sub-stage condensers with iris diaphragms, which allows greater control over lighting.

Colour balance
. The lighting systems on budget microscopes may give a strong orange hue to the final picture. To combat this, use a blue filter between the lamp and stage. Digital users can additionally set the camera’s white balance setting and make final adjustments in programs such as Adobe Photoshop (see examples).

Vignetting (darkening of the edges). This can be caused by microscope’s eye piece or sub-stage lighting. To combat the former, zoom in the camera lens - the effective magnification will increase and image quality may suffer. Sub-stage lighting problems can be reduced by opening the iris diaphragm (if fitted), though this may reduce contrast and render fine detail invisible; and by ensuring that the bulb is fitted centrally and not shifted to one side of its chamber.

Focusing. For digital users, the camera linked to a TV rather than relying on the camera’s monitor will prove very useful. It is usually best to set the camera’s to infinity and set the focus via the microscope’s controls.

Image enhancement (see examples)

Using a DSLR