Introduction
Digi-scoping has over the years increased in popularity and indeed the technology has made it much more accessible to the masses with equipment becoming cheaper. It is however a baffling concept for some people with a huge range of cameras, telescopes and adapter combinations. The aim of this brief article is to give a brief background to digi-scoping and help answer some common questions.
What is digi-scoping?
In essence it is taking a photo using a digital compact camera or digital SLR through a normal telescope (spotting scope).
The telescope increases the magnification of the digital compact giving several times more magnification. The amount of increased magnification is dependent on the eyepiece being used, the higher the magnification of the eyepiece the greater the final magnification. It is possible with this set-up to use the cameras optical zoom to zoom in or out on the subject.
With SLR’s the results are slightly different as the telescope acts as a prime lens with a fixed focal length. As a rule a telescope with an objective lens of 60mm will act as a 600mm lens whilst a 80mm objective will act as a 800mm lens. With this set up it is not possible to zoom in or out on a subject.
What do I need?
For digi-scoping you will need a camera (digital compact or digital SLR), a telescope, and in most cases an adapter. Some people forgo the use of an adapter and handhold the camera to the telescopes lens; adapters however make life a bit easier. With SLR’s it is essential to use an adapter as the telescope takes the place of the lens.
Which digital compacts are best?
With so many digital compacts on the market it would be impossible to keep an up to date list of all the recommended cameras so I will just give you a few basic rules to follow.
Zoom
This is one of the most important areas to take in to account when buying a camera for digi-scoping. It may seem obvious to go for cameras with a huge optical zoom of say 10x or more, but the results are usually very poor with such cameras because of an effect called vignetting. The photo below shows vignetting.
Photo 2 - Zooming in to over come vignetting.
The black circle round the edge of the photo is called vignetting; it is in effect the edge of the field of view seen through the eyepiece by the camera. To over come this problem the camera has to be zoomed in to narrow the field of view as seen in the second photograph. With cameras that have a large zoom rang i.e. 10x this effect is greatly increased and maybe so bad that it is not possible to overcome it at all. The general rule therefore is to go for a camera with a small zoom, 3-4 is best. This lower zoom also has the advantage of increasing the amount of light available to the cameras sensor.
Megapixels
A digital photo is made up of lots of tiny dots or pixels, as they are known, the more pixels in the picture the greater the detail. As you increase the number of megapixels in an image the size to which it can be printed and still retain detail also increases. An image taken on a 4 mega pixel camera can be enlarged to produce an A3 print at best with A4 size being most suitable. An increase in megapixels also allows the image to be zoomed in to greater depth before the image becomes blurred or pixilated.
The increase in megapixels does come at a price however as the amount of data it takes to record the image also increases, an image from a 4 megapixel camera take up less memory than the same image taken on a 8 megapixel camera. The speed at which and image is recorded to memory decreases with file size so should be a consideration. This will depend on the speed of the memory card being used and the memory buffer on the camera.
Many of today’s digital compact cameras have a megapixel rating of 8 or more and these will in general provide the greatest flexibility when it comes to editing and printing. With memory cards becoming cheaper and cheaper and faster and faster the increased file sizes that an image takes up and the speed at which it is written to the memory card is of less a concern.
Functions/modes
Many of today’s cameras come with several preset modes such as snow, landscape, portrait, sport etc these in effect change how the camera takes the picture. These limit the amount of control you have over how the image is taken. With some digital compacts however a range of manual controls/modes are included that allow the shutter speed, aperture, white balance, ISO etc to be adjusted manually by the user in accordance to the conditions and the results desired. Whilst some cameras do not have the full range of modes such as shutter priority or aperture priority they do include a manually mode that will enable setting such as ISO, sharpening, metering etc to be controlled to a certain degree, these are not usually as in-depth as the dedicated manual modes but are better than the normal camera presets.
I have found that digital compact cameras that have dedicated manual modes tend to produce more consistent results than those cameras with out, with this being most pronounced in less than ideal conditions such as overcast days or dull evenings.
Adaptors.
If you already own a telescope and do not wish to upgrade or change it its probably worth checking if the manufacturer of the telescope make their own brand of adapter for digi-scoping. It may be possible to attach a digital compact directly to their attachment making the process a bit easier. If they do do their own adapter it is worth researching how the camera attaches to it. Some adapters use a screw thread that can be attached to the thread of the camera lens. If this is the case it may influence the camera you buy i.e. finding one with a threaded lens. Some manufacturers whilst not producing cameras with a threaded lens do make an adapter that provides a thread to which additional lens can be attached (Sony is one such manufacturer). These additional adapters then make it possible to attach the camera to the threaded part of the telescopes digi-scoping adapter.
Nikon P5100 connected to Swarovski ATS 80HD using Nikon UR-E20 and Swarovski DCA
What about Digital SLR’s?
It is possible to use a digital SLR in the place of a digital compact. Finding out if your SLR will attach to a telescope is easier as the only thing you need to find out is whether the telescope manufacturer makes an SLR adapter for their range. If they do manufacture one it is just a case of buying the correct T2 mount to attach the SLR body to the adapter and telescope. The T2 mounts are usually available for the big SLR manufacturers such as Canon, Nikon and Pentax.
Canon 350d connected to Swarovski ATS 80HD using TLS800 adapter
