Fortunately the very useful derotate function in WinJupos will not only compensate for the rotation of the planet on its axis, but also for orientational drift due to this field rotation effect. Set up your scope and allow it to cool to reduce thermal currents, then collimate as normal.
Connect a digital video camera to the telescope and, looking at your laptop, focus critically on a star. Line up your finderscope so that Polaris is near the middle of the camera frame. Align on the planet and check the chosen exposure settings. Planet brightness should be about per cent of the saturation level and the gain about per cent of maximum. Reposition the scope so the finder cross-wires are just ahead of the planet.
As soon as the planet enters the camera frame, hit record. Keep recording until the planet drifts out of the frame. Quickly repeat. Keep going until you have gone outside the time window for your target. Process this output video in RegiStax or Autostakkert! Mounting your Dobsonian on an equatorial platform is your second option and gives your scope true equatorial movement for an hour or so before the platform needs to be repositioned back to the start.
Like the Go-To drive method, it maintains the low, stable centre of gravity of the Dobsonian design. With it you can continue to use the normal push-to altaz movements of the Dobsonian mount that are so much more in tune with the human frame of reference, but as soon as you have found the target it stays put in field as the equatorial platform tracks it.
An equatorial platform can be moved between scopes and even used to place a normal camera tripod on to turn your DSLR into a fully tracked camera. Commercial equatorial platforms are available from a number of different suppliers and generally are made for a specific latitude. For planetary imaging, absolute tracking accuracy from the drive system is not essential but it is useful to be able to adjust the drive speed slightly to keep the target in the field.
Some platforms also have a screw jack on the southern end to help move the object up and down in the field. Shown below is the layout of the optics of a Newtonian tube assembly. Light from a distant object enters the open tube and is reflected back up the tube by a parabolic concave mirror.
Because the mirror is curved the light focused into a point where an image is formed. A focusing unit is fitted to the hole to hold and adjust the eyepiece.
The eyepiece is a simple microscope used to magnify the image formed by the mirror. Using a variety of eyepieces with different focal lengths, higher or lower magnifications can be obtained. It has a Nylon disc mount on either side of the tube that sit in Nylon cups to provide a trunnion type bearing.
This allows the tube to be aimed up and down. These panels are mounted on to a turntable that allows the telescope to be rotated through a full circle. The telescope can therefore be aimed at any point in the sky. Drives are not normally fitted to this type of telescope. To help the observer to find and object a smaller telescope is fitted to the tube of main telescope this is called a Finder.
An astronomical telescope has a very narrow field of view, this means that only a very small area of sky can be seen.
This makes it very difficult to locate a specific object. The finder has a wider field of view so can be used to find the object first. Once centred the object should be visible in the main scope. Using a Dobsonian is very simple design making it an ideal telescope for the beginner. It is also a large powerful telescope made available at a modest cost. To enable a beginner to see astronomically interesting objects other than The Moon and the larger planets, a telescope of at least mm is required and most Dobsonians are of at least this size.
A mm Dobsonian is very quick to set up, in most cases all that is needed is to carry it from its place of storage to the observing position. It is almost instantly ready for use. Although, some come apart for easy transportation! We can twist and turn the scope to the Moon, to Mars, and the stars. Dobs are equipped for viewing these further and fainter objects as well, although tracking these can be quite a challenge without a properly integrated system.
Perfect for beginner and amateur astronomers. A Dob can be up and running in just a few minutes from box to backyard. Dobsonians do not suffer from the image distortion caused by chromatic aberration in refracting telescopes.
Just point and take a look! These are among the simplest designs around for telescopes. Once assembled it requires no more than the point-and-look method—unless, of course, the eager astronomer in you opts for one with tracking technology. This type of telescope is generally not used for astrophotography purposes.
For that purpose, a telescope with an equatorial mount would serve you better. Nonetheless, a Dobsonian certainly can be used for astrophotography on a more local scale such as our neighboring planets and the Moon. This need not be a hassle either with help from one of many collimation tools available.
Simply attach the collimator to the eyepiece port and adjust the mirror knobs on your telescope until aligned. Now you might also be wondering: Why would I need to realign my mirrors? Why do the mirrors lose their alignment?
Great questions again. We can think of the mirrors like strings on a guitar, and we all know the necessity of tuning that guitar properly. Everything we love in life requires a little maintenance and our scopes are no different.
This first scope is the ultimate in portability and ease of use. Small and light enough to fit into an adult backpack, this telescope is ideal for convenience and family use at an extremely affordable price.
The Meade EclipseView mm Reflecting Telescope is an excellent choice for the aspiring astronomer looking to get just a bit more serious in their stargazing. Slightly bigger than the previous telescope, the EclipseView will enable a keener eye to the sky.
Now we get to the first of the more big-league telescopes. Able to get up close and personal with deep-sky objects like nebulae and galaxies but also staying intimate with our own moon, this telescope will guide you through the cosmos with its built-in computer database.
0コメント