How to Use Telescopes : Schmidt-Cassegrain Telescopes

Schmidt-Cassegrain telescopes use mirrors and lenses to form a telescope incorporating Newtonian mirrors and a redirecting lens. Study Schmidt-Cassegrain telescopes with an observatory director in this free astronomy video.

Expert: Rocky Alvey & Billy Teets
Bio: Rocky Alvey is the assistant director of the Vanderbilt Dyer Observatory and has been involved in astronomy since 1969.
Filmmaker: Dimitri LaBarge

Comments

MND0520 says:

What? o_O

John Carter says:

The key thing to keep in mind about this method is that the OTA does not have to be perfectly parallel to the tines at the outset. But if you insist, use any device to measure the angle of the base (any arbitrary initial position will do) and then set the OTA to be at the 90 degree complement of that angle. At this point, the OTA is nearly perfectly parallel to the tines. After making the video adjustments several times, the OTA will be more accurately parallel to the tines.

More to come…

John Carter says:

Once the telescope is adjusted with this method, you should see Polaris always close to and within the center ring of a Telrad as you swing the mount’s tines from the horizontal to the vertical position (Declination motion). At this point, you should be centered at or near the celestial North pole (CNP).

Using an eyepiece that gives you about a 40 arcminute FOV, you might be able to make out three stars (TYC4643-26-2, TYC4627-64-1, and TYC4661-2-1) that almost perfectly triangulate the CNP.

assassain54 says:

I got a Question…
Why are the cassegrain Soo Expensive??
Is it because of the Quality Or Something??
Some Please Reply It would really Help Me And others…

Destiny Price 420 says:

they are under the back plate. but in most cases you do not set them just the front. the rear mirors are used in focusing. and are set and locked. hope it is not out of align. good luck

John Carter says:

Another key element to this method is that Polaris must always be in the field of view as you swing the tines from horizontal to vertical (the Declination motion). Using a 8×50 finderscope gives about a 7 degree field of view (FOV), which is a bit much. A Telrad gives about a 4 degree FOV, which I find adequate. A Rigel Quickfinder gives about a 2 degree FOV, which should be optimum.
More to come…

biggrex says:

that was short

ParaglidingManiac says:

My Shmidt-Cassegrain’s secondary/corrector plate doesn’t have collimating screws. Is that how it’s suppose to be, or am I not looking good enough? Thank you!

Destiny Price 420 says:

the mirrors have to be made as a pair the center of the primary is cut for the hole to allow the optical tube. they are alot more work than newtonians. but they do have a larger focal lenght and are more compact in design. that is a meade 8 inch F10 it run around 1799 with ACF there is a jump from the 12″ to the 14″ it is about 3000 dollars difference

ParaglidingManiac says:

Meade. In case it still matters to you:)

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