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Angle Eyepiece

What Are the Different Scientific Instruments?

Aside from the laboratory instruments we are familiar with, astronomical instruments are another type of Scientific instrument. Understanding their various categories and formulas will help you determine its proper usage.

Scientific instruments are not confined to laboratory equipments only. An example is the Hubble telescope. Particular categories of scientific instruments include the following:

• Measuring instruments

These are devices used to measure or compare the magnitude of physical properties such as:

- voltmeters
- speedometers
- timers and
- clock
- weighing machines and others

• Analytical instruments

These are devices used to measure multiple or complex material properties like mass spectrometers.

• Astronomical instruments are used to:

- observe
- record and
- measure the position of heavenly bodies such as

* Stars
* Planets
* Comets and others

Here are examples of astronomical instruments:

An Optical Telescope

The function of a telescope is to gather light and to magnify the image. The bigger the main "light-collecting element" of the telescope, more light gets collected. It is actually the whole "amount of light" collected that determines the level of detail.

All Optical Telescopes are categorized into one of three classes:

1. The Refracting Telescope

With a refracting telescope, light is collected by 2-element objective lenses. It will then bring it onto a central plane.

2. The Reflecting Telescope

A reflecting telescope uses a type of concave mirror to collect light.

3. The Catadioptric or Mirror-Lens Telescope

A Mirror-lens or Catadioptric telescope uses a good combination of these lenses and mirrors. It results to a shorter and more convenient optical tube assembly.

All Telescopes use an eyepiece. It is located behind the central plane. This is to enlarge the image formed by the major optical system.

Other instruments can be placed in the central plane for different purposes. These purposes include the following:

- photo-electric cell to measure the luminosity
- the slit of a spectrograph to evaluate the light or
- thermo-couple to measure temperature

The advantage of a reflecting telescope is that it has no chromatic irregularity. Mirrors can be made to a much larger size.

The enlargement of a telescope is given via this formula:

M = OF / f, -------------------- (1)
where OF is the central length of the objective and f that of the eyepiece.

The resolution limit of a telescope is given via this formula:

R (in sec of arc) = 2.3 x 105 x ( /A), ------------------- (2)
where is the wavelength and A is the diameter of the aperture.
For example, if A = 100 cm and = 4000 x 10-8 (yellow light) then R = 0.092"

INTERFEROMETER

An Interferometer is used to determine the size of astronomical objects. This is through careful analysis of the following:

- resulting interference pattern,
- position of a point source or
- Fine details in an extended one can be resolved.

The same formula is done for the resolution that is appropriate except for aperture A. Aperture A is replaced by the baseline between the two receivers. This method has been widely used via Radio Telescopes. It is also applied with the use of optical telescopes.

RADIO TELESCOPES

Radio Telescopes are instruments for collecting radio waves from outer space objects. The wave is reflected from a parabolic dish towards an aerial plane situated at the center. The signals are led onto a radio receiver.

The wavelength of radio waves is very large (from 0.3 mm to 30 cm). The radio telescope, having an aperture comparable to the optical telescope, has a very poor resolution. A considerable increase in resolution can be gained with the use of an interferometer.

A collection of the same antennae that is spaced at regular intervals will show that the elevation angle of a celestial object can be calculated. It can be computed from the time difference as well as the distance between the receivers. The angular separation can travel from the difference of the elevation angles and equal to the resolution of the time difference.

Hence, scientific instruments are devices made in order to assist in conducting Science. Examples would be found in a chemistry or biology laboratory. This includes:

• test tubes
• glass wares use for experiments and others

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eyepiece collection?

please rate my eyepiece collection:

telescope=Celestron Starhopper 8 inch dobsonian f/6

*numbers represent focal length in millimeters

Huygen-12.5, 6,

Kellner-10, 15, 25,

Housebrand Plossl-6.5, 10, 12.5, 15, 20, 25, 30, 40

Housebrand Ultra Wide Angle-11, 16

Super Plossl Series 4000-9.7, 26

Celestron Plossl-25

Orion Expanse-6, 9, 15,

Barlow 2x-Orion Shorty, Housebrand Barlow 2x aluminum

Will use my Huygenian Eyepieces for solar viewing,
Plossls and UW Eyepieces for astronomical viewing, Orion Expanses for planetary viewing, and Kellner for back up lenses (show and tell at star parties).

which eyepiece(s) do I not need? quality in; for example, i've got a SP 26mm, Housebrand Plossl 25, and Celestron Plossl 25. Obviously, I've got two extra.

Thanks. Hoping to sell unnecessary eyepieces
Best suggestions get best answer

Eyepiece preference is a personal thing, so you'll have to decide which ones are keepers. I think six eyepieces plus a barlow constitute an adequate collection - something like 6, 9, 12, 16, 25, 30. The 40 mm Plossl (assuming it's a 1.25") has a narrow apparent field and shows about as much sky as the 30 mm, so it can probably go. If you haven't already formed an opinion, compare the performance of your 25-26 mm Plossls and keep the best one. Consider whether you need both 20 and 25 mm focal lengths; you may find you have three superfluous eyepieces. Choose one from the 9.7-10 mm, too. Depending on how good the Plossls are, you might want to get rid of the 6.5, 9.7, 10, and 15 and use the Expanse eyepieces exclusively.

Huygens for solar viewing? Are you doing solar projection? Not a good idea with a reflector, as it can focus the sunlight on the inside of the tube and burn it. And if your secondary is glued on, the heat can weaken the bond and make it fall on your primary. Better to get some Astro-Solar film and make a Solar Filter.

As I see it, you could sell maybe eight of your Plossls. Decide which focal length you get the most use out of, and put the money towards a premium eyepiece in that focal length. Buy used on Astromart ( http://www.astromart.com/ )for the best deals.

Snail kite eating an apple snail

Orion SkyQuest XT10i IntelliScope Dobsonian Telescope $729.99 This remarkable scope combines powerful 254mm-diameter reflector optics with point-and-view simplicity in one nicely portable package. And with included Computerized Object Locator, even the first-time stargazer can pinpoint the location of 14,000+ celestial wonders stored in the IntelliScope's databank. It's like having your own personal tour guide to the universe! The optical tube houses an 10" ...

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Super Wide Angle 16mm Plossl 1.25 Eyepiece $24.99 SUPER WIDE ANGLE VIEW CHOCKING HAZARD - CONTAINS SMALL PARTS - NOT FOR CHILDREN UNDER 3...

Nikon 7216 Action 8x40mm Binoculars $62.00 New Nikon 7216 8X40 Action Birding Binoculars W/Case.Includes deluxe case, strap, instructions, and box..Aspherical eyepiece lenses with multi-coated prisms Quick central focus system 420-foot field of view at 1,000 yards Magnification: 8x Objective lens: 40mmLike the Actions with 50mm objective lenses, the 8x40 and 7x35 models in this ever-popular series have been updated with enhanced and ergono...

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Celestron 93230 8 to 24mm 1.25 Zoom Eyepiece $53.95 The Celestron 93230 8 to 24 millimeters 1.25 inch zoom eyepiece allows you to zoom instantly with your scope from 8x magnification to 24x magnification....

Orion SkyScanner 100mm TableTop Reflector Telescope $99.99 Although perfect for beginning stargazers, this telescope is not a toy! The Orion SkyScanner 100mm TableTop Reflector is just the right size - large enough to see night sky objects yet compact enough to sit on a desk. The wide field of vision is ideal for observing detailed moon craters and even the spectacular rings of Saturn without having to leave town. Under darker skies, the SkySkanner has en...

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