Posts Made By: Allen Tracht

Stu,

As no one else has replied, I thought I'd give it a shot:

Without a more full explanation, it's hard for me to really know your intent, but a few things come to mind:

The diagonal of a conventional scope is far from the point at which the primary forms an image (the prime focus). Replacing the diagonal with a CCD would give a very blurred image.

Assuming you mean to place the CCD at the prime focus, using software to improve the image is a dicey proposition for astronomy because such techniques (such as deconvolution) typically increase the effects of noise, though this might not be a problem for bright objects.

In general, improving the image optically before detection has a great advantage as the detector only records the intensity of the light, and not its phase (or direction). Recording the phase information is the "trick" that makes holograms work.

I hope this helps.

Allen

Televue's eyepiece spec table at http://www.televue.com/engine/page.asp?ID=144 gives the more obvious differences: The type 4 has more eye relief but is larger and heavier.

I really like the type 4, but I can't say how it compares to the type 5 in optical quality or useability. For use with my eyeglasses, the type 4's extra eye relief is a big advantage. YMMV.

Allen

Certainly photons can tunnel. Simple experiment: take two diagonal prisms, remove them from their holders. Place them base-to-base with a small air gap between them. If the air gap is large enough, the prisms will act "normally" demonstrating total internal reflection. As the air gap shrinks, some of the photons tunnel across to the other prism. Of course, when the air gap is reduced to zero, all of the photons pass into the other prism.

Of course, there is a classical physics explanation for this effect, involving evanescent waves, but the quantum-mechanical explanation (tunneling) works as well.

Even if you could get photons to tunnel through the iris, I wonder if a larger pupil would help? Sure, the image would be brighter, but you'd be using the edges of the cornea and lens, making their optical defects more noticable.

Instead, you might (more sci-fi here) direct the photons to the exactly correct spot on the retina. But the eye moves in deliberate patterns to build a complete image. So, you'd have to understand the visual perception process (including the brain's role) in detail.

Now that you understand the brain, you could just excite the correct nerve cells and dispense with the eye altogether! The image would be as bright, sharp and clear as you could imagine.

Thanks for the opportunity to speculate.

Allen

I'm no expert, but it looks like a glint of the room lights reflected from the diagonal holder. If you move the scope, does the glint move?

Allen

You might also try:

http://www.astromart.com/classifieds/details.asp?classified_id=406011

The ServoCat manual has a diagram that you might find useful.

http://www.stellarcat.com/Graphics/ServoCAT_v8.pdf

However, you probably need something better than a Telrad to see the stars in the chart. Also, I don't know how accurate it is over time.

Allen

I found these details interesting:

http://hirise.lpl.arizona.edu/HiRISE/papers/6th_int_mars_conf/Delamere_HiRISE_InstDev.pdf

Allen

On the other hand, the TeleVue warranty explicitly doesn't apply to second-hand equipment:

http://www.televue.com/ask_al/telescopes/0266.html

So, check with the vendor (or dealer) in question.

I've always liked the free monthly star charts from http://skymaps.com/ Each month's chart is a double-sided 8-1/2 x 11 page, with a chart on one side and lists of objects (and other details) on the back.

I also see that they are free for non-commercial, educational use. They might make a fine handout.

Allen

Just a thought...

Have you considered remounting the OTA to give more clearance? You'd need counterweights to restore the balance.

Allen