by Michael Portuesi.

Jason 313 Discoverer Telescope Manual

You might have read elsewhere on this site my warnings to avoid department store telescopes. Not only are the optics small and not good for showing you much, the telescope usually comes on a very flimsy tripod that won't keep the scope stable for aiming and viewing. Such telescopes have demoralized many would-be astronomers and caused them to run fleeing from the hobby.

Perhaps you own one of these scopes. My advice is to return it to the store if possible or simply discard it, and buy a quality telescope from a dedicated telescope store. But let's say you are committed to making the best use of it. What can you do to make it usable?

Information on Jason Telescopes - posted in Classic Telescopes: My father bought my daughters a telescope when they were little. They dont care for it now. I am going to sell it but have no idea what to ask. The telescope is a Jason 454 in very good condition,has the manual and various other parts. Would anyone know what to sell it for? Insert a low power eyepiece into the telescope's focuser. Locate a bright object and position the telescope so that the object is in the centre of the field of view. With both eyes open, look through the sight tube at the object. If the red dot overlaps the object, your Red Dot Finder is perfectly aligned. Get the best deals on Collectible Telescopes when you shop the largest online selection at eBay.com. Free shipping on many items. Vintage Jason SS1 SHUTTLE SCOPE Telescope USA NASA with Box Manual Lenses Tripod. $30.00 shipping. Jason Discoverer Telescope 454 Model EQUATORIAL Refractor Telescope.

Get Better Eyepieces

Paul, I inheredited a 'Jason rotary powered 540' telescope. What can you tell me about this item and where can I get an instruction manual? What you have here is a simple refractor telescope that was made for the masses.

Ask any astronomer, and they will tell you that the eyepiece is half the telescope. The optics in the eyepiece focus the light from the lens or mirror into your eye; there are several designs available, each with its own special purpose.

Cost-cutting in Eyepiece Land

The eyepieces you get packed with department store scopes are, unfortunately, even lower quality than the scope itself. They are often mostly plastic, with optics that will give you fuzzy images. They have a very narrow field of view, so you get the feeling you're looking at the universe through a soda straw. And you have to place your eye very close to these eyepieces in order to see anything (this is called poor eye relief).

These eyepieces are especially bad for people who wear eyeglasses. Some department store scope owners have told me their scope doesn't work at all - when in fact, they couldn't get their eye close enough to their eyepiece in order to see anything.

The pack-in eyepieces are victims of cost-cutting in another way. Nearly all serious astronomical telescopes use standardized sizes for eyepieces. Most eyepieces have barrels 1.25 inches in diameter. This allows you to buy eyepieces from one manufacturer, and use them with scopes from another manufacturer. Larger scopes often have 2 inch focusers, which can accomodate eyepieces with 2-inch barrels (often low-magnification, wide-field eyepieces) or standard 1.25 inch eyepieces. Department store scopes have eyepieces that are 0.965 inches in diameter, presumably to cut costs. There are a few companies that make eyepieces in this size, but not many.

Here's a photo comparing a pack-in eyepiece (left) with a value-priced but quality 1.25-inch eyepiece (right). You can immediately tell the difference in quality, just by looking at them:

Upgrading to 1.25-inch Eyepieces

You will enjoy the view much better if you purchase some third-party, 1.25 inch eyepieces for your scope. And the best part is that any 1.25 eyepieces you buy will also work with the next telescope you buy. And I do hope you will upgrade!

In order to use a 1.25-inch eyepiece with the .965 focuser in your telescope, you will need a .965-to-1.25 inch adapter. You can purchase this adapter at nearly any telescope store. This will cost perhaps $15-$20.

Next, you will want to purchase some quality eyepieces. The lowest you should expect to spend on a quality eyepiece is about $30. Really fancy eyepieces can cost hundreds of dollars each, even more. But for right now, just get some PlÃ¶ssl eyepieces. This design is well-regarded as the best all-around eyepiece. You can find good ones, from several manufacturers, for about $40-$60 at nearly any telescope shop. I recommend you buy one low-power eyepiece, about 25mm focal length, to help you find things with its wide field of view. Then, also get a high-power eyepiece, perhaps 10mm focal length, to help you view details on the Moon and planets. (The lower the focal length, the higher the magnification).

Finally, if your budget permits, you might consider investing in a Barlow lens. This lens goes into the focuser before your eyepiece, and doubles the magnification of your eyepieces. Combined with the 25 and 10 mm PlÃ¶ssls, this gives you the equivalent of four eyepieces: 25mm and a barlowed 12.5mm equivalent, and 10mm with a barlowed 5mm equivalent.

Get a Better Aiming Device

Telescopes often have another little tiny scope attached, called the finderscope. The finderscope shows you a larger region of the sky than the view you get through the main eyepiece. Its purpose is to help you locate objects in the sky.

Unfortunately, the finderscopes provided with department store telescopes are difficult to use, and next to useless. Instead, pick up a red-dot finder to use with your scope. These finders (also called unit power or reflex finders) simply project a red ring or dot on the sky when you look through them. Basically, they act as a 'gunsight' to allow you to accurately aim your scope. Wherever the bullseye points, your telescope does too.

For a department-store scope, a red-dot finder will give you a big help for finding objects in the sky.

A red-dot finder will cost perhaps $25-$30. As with quality eyepieces, the red-dot finder can be used with any future scopes you might purchase. You can also buy additional mounting brackets for very little cost, and share the finder between telescopes.

Stabilize the Mount

The mount (tripod, plus the apparatus that holds the telescope tube) in inexpensive scopes is often not very sturdy. Experienced observers know that a sturdy, stable mount is important. Because telescopes use high magnification, any vibration of the scope will be magnified accordingly. This will make it difficult to see objects and focus your telescope. Even expert observers find it difficult to use the mounts supplied with department-store telescopes.

Here are some simple techniques you can try to make the mount more stable.

Tighten the wing nuts at the top of tripod, where the legs meet the mount head. This will make everything stiffer.
Lower the tripod legs. If you can lower the tripod legs, and still reach the eyepiece, this is an easy way to stabilize the scope. The lower the scope is, the less motion can occur.
Suspend a weight from the tripod head. Get a gallon milk jug, fill it with water or sand, get a strong cord or rope and hang the jug from the bottom of the mount head. The extra weight will prevent the mount from moving and dampen vibrations.
Cut a triangular piece of wood to use as a brace, and wedge it between all three tripod legs just below the tripod head. This brace will stiffen all three tripod legs. You can drill a hole in the middle, to run the cord for your milk jug through.
Fill the aluminum legs with sand, lead shot, or foam. This absorbs vibrations, though you will have a heavier mount.
Try vibration supression pads. These pads are round rubber discs you place between the ground and the bottom of the tripod legs. They absorb vibration in the tripod legs. Commercial pads cost about $45-$50, but you may get results cheaply by using three hockey pucks.
Attach a chain to the telescope tube. Get a three-foot length of metal chain, with one-inch links, from the hardware or home improvement store. Drape the chain over one end of the telescope tube, and fasten with some duct tape. As the scope jiggles, each link in the chain will absorb a little bit of the vibration and quickly dampen

Jason Rotary Power Telescope Manual