How do I connect my camera to my telescope?

There are different ways tot connect a camera to your telescope. An often practised way is using a T2-ring and a camera adapter. Your camera is placed directly in front of the telescope, with the telescope lens more or less taking over the function of the camera lens. The T2-ring is the connection piece between the camera and the camera adapter. The camera adapter itself is connected to the telescope. This way, your telescope will be suited for astrophotography. You can find the T2-rings, as well as the camera adapters, in our shop.

Preparation

A lot more is involved. In astrophotography, for example, a lot less light is available so a longer shutter time is needed. As celestial bodies move relative to the earth, the equipment needs to be well-adjusted. All in all, a good preparation is highly recommended.

Getting started with astrophotography

In order to make things easier for you, we have already done some thinking. One the following pages you will find the equipment that you need for a razor-sharp photo report. You will definitely get optimum results with this equipment. In the manual below we explain everything step by step.

Longer shutter times

Astrophotography involves longer shutter times. This is because stars and nebulae et cetera are dim. Shutter speeds vary from split-seconds to several hours. The longer the shutter time, the bigger the illumination angle. In astrophotography adjustments are usually done manually. For this you need a (digital) reflex camera or a compact camera of good quality. These cameras enable you to manually adjust exposure time.

Digital astrophotography

As astrophotography initially is a matter of trial and error, you will have to try out the settings a few times before you will be able to take a good picture. As you may have already gathered, it is easier to work digitally. After all, in digital photography you immediately see the result. Moreover, you can edit the photographs on your computer. Furthermore, it is recommended to look for a dark spot. Do you want to take astronomical pictures in a densely populated area such as London? Then it is wise to cycle out of the built-up area to a remote spot.

What kind of camera do I need?

The camera (preferably) meets the following requirements

• the distance needs to be manually adjustable to infinitely
• you need to be able to set shutter time (exposure time) to 'B'; this way, you are able to determine the length of exposure yourself (if this function is absent, then set your camera to night mode)
• your camera needs to have a tripod fitting
• you need to be able to mount a cable release on the shutter

Aperture

Adjusting the aperture size: f/1, f/1,4, f/2, f/2.8, f/4, f/5.6 and f/8, f/11 et cetera. The smaller the number, the bigger the aperture opening. The bigger the aperture opening, the bigger the illumination angle. For example, an f/2.8 is more suitable for night photography than an f/4.

ISO

Film speed of a film in roll form or film speed of a digital camera is expressed in ISO. The number varies from 100 to 400 in simple cameras and runs to 6400 in more expensive cameras. The ISO value indicates how fast the sensor reacts to the light that falls on the sensor after having travelled through the lens. This extra film speed, however, comes at the expense of sharpness: the ‘grain’ becomes bigger. At ISO 400 this is not really a problem, but when you start working with ISO 1000, this ‘graininess’ becomes clearly visible and a bit of a nuisance.

Longer illumination

In respect of all objects outside our solar system it is, of course, true to say that the longer you illuminate, the better! Unfortunately, the terrestrial atmosphere is a spoil-sport. Even in the darkest spot of Europe, the background of the sky gradually begins to fade over time. Thus, you will have to keep exposing until the sky background is just (or not quite) visible in the picture.

Editing afterwards

When taking photographs with a digital camera, you are able to edit the result on your computer after the shoot. You can use programs such as Photoshop or Irfaview to decrease photo size from 1600 x 1200 pixels to 400 x 300 pixels. This produces sharper, less grainy pictures. You may also adjust clarity, colour contrast and saturation to get clearer results.

Eyepiece projection

Do you want to further magnify the film image? Then use an eyepiece. This method is called eyepiece projection photography and is mainly applied in planetary and lunar photography. Using an eyepiece will lengthen exposure times. This, in turn, necessitates the use of a tracking motor. For even bigger magnifications you use a Barlow lens. All these items are naturally available at Frank.

The next step

When working with longer shutter times, you will have to take into account the rotation of the earth. Celestial bodies will move during your photo shoot. Therefore, you should make sure that your camera moves along with this rotation in order to prevent field-rotation (field rotation: the picture shows stripes instead of stars). There are various ways to prevent field-rotation. You can use a piggyback, for example, a flip mirror system, a wedge telescope, a telescope with a field de-rotator, a tracking motor and/or a Go-to module. Needless to say, we can supply all these products.

What kind of mount do I need?

A telescope with alt-azimuth mount will be sufficient for shutter times up to 30 seconds. Longer shutter times require a tripod with parallactic mount. All this is available at Frank.