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Binoculars and Telescopes |
Buying Optics for Birdwatching - General Advice
Care and use of Binoculars and Telescopes
Choosing a Telescope
Basics for Binoculars
1. Don't buy without trying; it is your eyes and pocket they have to suit. Many good retailers hold field days where you can compare models in semi-field conditions; some retailers are actually located in the countryside.
2. On average, price is a good indicator of quality.
3. Bins are described with 2 numbers, e.g. 8x32. The first number is the magnification, the second number the diameter of the object lens in mm. Dividing the second by the first gives an indication of the light gathering power; for full size binoculars try not to go much below a figure of 4 (there are some jolly good 8x30s around); for minis a figure a little further below 4 will usually still be acceptable.
4. For all round use a magnification of between 8 and 10 is appropriate; you will probably not be able to hold anything over 10 still and anything much below 8 may leave you wanting to get closer views.
5. Remember they will be around your neck for quite long periods: weight can be a worry. Good quality comfortable straps can help to take the load when they are round your neck. When holding them to your eyes you will find that the better the balance the less you will notice the weight.
Basics for Telescopes
1. Until you are sure you are going to enjoy birdwatching it is probably better not to invest in a telescope. Once you are sure, it is hard not to enhance your birding pleasure with one!
2. As with binoculars, do not buy without trying. Much depends on your personal preference, particularly whether the eyepiece is at an angle to the 'scope or looking straight through it.
3. On average, price is a good indicator of quality.
4. A tripod is essential.
5. The lowest sensible magnification for a telescope is about 20x. An object lens diameter of less than 60mm is unlikely to provide enough light to support a magnification much bigger than that. The bigger the object lens, the higher magnification it will support, but the higher the magnification, the smaller, usually, the field of view. Most will take interchangeable eyepieces, so you might choose to have both 20x and 40x, or you might pick a 30x (some of which are specifically designed to provide a wide angle of view).
6. Zoom lenses offering magnifications all the way from, say, 20x to 60x, might appear to offer the all purpose answer to the question of magnification, but at each level of magnification they offer less light and field of view than a lens of that magnification alone. Only you can decide whether this matters for the sort of birding you enjoy.
7. A comfortable strap is essential to make telescope and tripod easily transportable despite the weight.
With Grateful Thanks to:
Peter and Carol Wilkinson,
Wheathampstead, Herts
Having chosen your new binoculars or telescope, how do you get the best from them? As these are the most expensive tools for birdwatching, it is worth taking a little time to learn how to achieve the best results and keep them in good working order for years to come.
The basics
When you first get your binoculars, throw away any lens caps as a case is adequate protection; fix the strap and the rainguard. They are now ready to use. If you do not use them regularly, store them in the case away from any dust. Many birders do not use a case when out in the field but it is useful to keep for travelling and storage.
After using binoculars in the rain, always wipe them dry. If moisture has got inside, leave them in a warm place to dry. Never open them up and do not put them back in the case until they are fully dry. Treat a telescope in the same way.
Clean the lenses as little as possible. Use a lens blow brush to ensure there are no grains of sand and salt present which would scratch the lens, before wiping the lens with a clean lens cloth.
If Your telescope has interchangeable eyepieces, change them as little as possible - every time you remove the eyepiece, dust will get into the telescope.
The most common fault with any binoculars is being knocked out of alignment. No matter how well made your binoculars are, if you drop or knock them, they may need realigning. This is easy enough to do but it should be carried out by a trained repairer. The owner often does not notice a slight alignment fault, so ask a friend to check your binoculars occasionally.
How to use your binoculars
When you first look through binoculars you should:
Most binoculars come with a strap which you may wish to change. There are many different types on the market - some people prefer a wide webbed strap, others choose a neoprene rubber one which reduces the weight effect around the neck. Rainguards are often not supplied but are essential if you are out and about with your binoculars. Make sure the one you choose fits over the eyepieces when they are in their normal position for your use.
Spectacle wearers
If you do wear spectacles, it is important to choose a suitable pair of binoculars as there is nothing more frustrating than losing a bird because you have to take your glasses off to use your binoculars. Most telescopes can also be fitted with an eyepiece suitable for spectacle wearers.
How to use your telescope
A telescope is never a substitute for binoculars and it takes time to learn to use one - but it is worth the effort! The following points should help you:
Using a telescope and tripod
It is a good idea to carry your telescope ready mounted on a tripod so that it is easy to use quickly. A strap can be useful, although many birders carry their telescope and tripod on their shoulder, making it easy to use quickly.
A tripod with a quick-release plate will be useful in hides. If your tripod does not have this, it is possible to fit one as an accessory.
When using the tripod, always make sure the legs are locked tight and are placed on a firm surface. For safety, it is always advisable to have only one of the tripod legs facing away from the wind.
When you are out in the rain and not using your telescope, keep the lens cap on. For extra protection a stay on case' is a good idea. Once fitted, these should be regarded as a permanent part of your telescope.
Other supports
Mini tripod: useful as a support on a hide shelf or car roof.
Hide mount: good lightweight support for clamping to the shelves in hides.
Car window mount: of limited use as they only clamp to the window of a car and are prone to vibration from other traffic.
Monopod: this does little more than steady the telescope but can be useful if size and weight are a problem.
Universal mount: ideal for clamping to fences, etc; can also be used in some hides.
A support of some sort is essential as it is only possible to use a telescope for a limited time and at low power while resting it on a fence or ledge.
Be sure to try several models before making your choice. The RSPB runs field days where you can try different models under field conditions. This will help you make sure you are completely happy before purchase. Contact your local RSPB shop for details.
Telescopes are increasingly popular among birdwatchers. By offering higher magnification, they add a new dimension to birdwatching. Telescopes come in component form-the body, eyepiece and appropriate support, usually a tripod. It is important to take care when choosing your equipment.
What magnification do I need?
Telescope magnifications range from 15x to 60x. Some specialist instruments offer even higher power. If the telescope has a fixed eyepiece, 20x or
30x is normal.
Most telescopes on the market have a range of interchangeable eyepieces, so you can choose more than one. Wide-angle eyepieces of 20x to 30x are good for general use; a 40x might be useful for longer distance work.
When using higher magnification, the image brightness and field of view decrease dramatically. Any shake from the support also becomes more evident. In practice, this means that the higher power eyepieces are best used in bright conditions for stationary birds. Bigger is not necessarily better.
Zoom eyepieces work well with some telescopes, usually the ones with a larger objective lens. The range covered can be 1 5x to 40x or 20x to 60x. But remember, on the higher power, the amount of light passing through to the eye will be reduced.
The smaller telescopes have 60 mm objective lenses and, because this makes them compact, they are ideal for general work. A 20x or 22x wide-angle eyepiece will maximise the light reaching the eye.
Some manufacturers offer telescopes with larger objective lenses, between 75 mm and 80 mm. These perform better in low light, but the large lens adds to the size and weight of the instrument. Because of the increased light transmission, zoom eyepieces work better with this type of telescope.
Basic guidelines
i) For general use, choose a compact 60 mm telescope with a wide angled 20x or 22x eyepiece. ii) if you need higher power, choose a 30x or 40x eyepiece in addition to, but not instead of, the general one.
iii) The larger 75 mm-80 mm telescopes are ideal for use in low light or from a fixed position such as a hide. Again the wide-angle, fixed 20x-30x eyepieces are best, but a zoom works well with this type of telescope.
iv) If you wear spectacles, choose an eyepiece which has a fold-back rubber eyecup, although you will still lose some field of view.
Straight or angled eyepiece?
Most telescopes come in either straight or angled form. On the straight type, the eyepiece follows the light path from the objective lens. On the angled type, the eyepiece is at 450 to the telescope body. Both designs have their advantages:
Straight
Angled
The angle of the eyepiece does not affect the performance of the telescope and your choice is a matter of personal preference.
How much should I pay?
The starting point for a good 60 mm telescope with a fixed eyepiece is £350: add £100-iso for a zoom eyepiece.
From £350 to £800 you will find better telescopes and this is the starting price for the instruments with larger objective lenses.
Over £500 buys you a telescope of the highest quality. Some top of the range instruments have low-dispersion (ED) or fluorite glass, giving a brighter and sharper image. Sixty millimetre telescopes with this type of glass will out-perform larger models.
Be sure to take into account the cost of a good tripod when making your selection. A telescope is only as good as its support.
Some telescopes are waterproof, but it is worth getting a case or a model with rubber protection. Stay-on cases are a good idea and are available to fit most models. These offer better weather protection and help protect against knocks.
Can I use my telescope for photography?
In most cases, yes, but it is worth remembering that a telescope is designed to look through, not for taking pictures, and the results will not be as good as with a true camera lens. When using a telescope as a camera lens, always use fast film (400 ISO or more) and try to match your camera's shutter speed
to the focal length of the telescope. In practice 1/500th of second is the minimum that should be used. Make sure you use a good tripod or support, as any movement will cause camera shake and blurred pictures.
Using your telescope
Once you have made your choice, the following points will help you get the most from your telescope:
This page was co-written by Viking Optical Ltd of Halesworth. For further details on Viking Binoculars and telescopes, contact them at:
Viking Optical Ltd
Blyth Road
Halesworth
Suffolk
P19 lEN
Telephone 01986 875315; Fax 01986 874788.
A full range of binoculars and telescopes are available from the following RSPB Gift Shops:
ENGLAND:
Bempton Cliffs, Yorkshire, tel 01262 851179 (shop opening hours vary seasonally);
Leighton Moss, Lancashire, tel 01524 701601;
Minsmere, Suffolk, tel 01728 648281;
Pulborough Brooks, West Sussex, tel 01798 875851;
Radipole Lake, Dorset, tel 01305 778313;
The Lodge, Bedfordshire, tel 01767 680541;
Titchwell Marsh, Norfolk, tel 01485 210779.
SCOTLAND:
Lochwinnoch, Strathclyde, tel 01505 843026;
Loch Garten, Inverness-shire, tel 01479 831476;
Vane Farm, Kinross-shire, tel 01577 862355.
Edinburgh (Charles Frank shop) tel 0131 225 6389.
WALES:
Lake Vyrnwy, Powys, tel 01691 870278.
Binocular drawing by David Parkins.
Bird images courtesy of the RSPB Image Library: www.rspb-images.com
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