Future Aperture's & weird Ideas

[AdeyBuzz]

Anyone else dreaming of a 500 - 700mm 10inch SCT? just for the extra light or camera's with wider light gathering, any rumours going around on development from celestron or meade? And would there be any issues with such a device other than the corrections would be quite extreme, but surely it's possible. anyone else got ideas or some future tech? How about a dome make of O111 glass that you can sit in to get rid of light pollution, be a nightmare to keep clean and scratch free :))

my first post and this has been on my mind everytime I look through the books, trying to decide on a widefield refractor or a should FL SCT

Buzz

[CraigT82]

Allow me to make your dreams come true...

https://www.firstlightoptics.com/optical-tube-assemblies/celestron-rowe-ackermann-schmidt-astrograph-telescope.html

[michael8554]

"

Baker–Nunn[edit]

 

One of the Baker–Nunn cameras used by the Smithsonian satellite-tracking program

The Baker–Nunn design, by Baker and Joseph Nunn, replaces the Baker-Schmidt camera's corrector plate with a small triplet corrector lens closer to the focus of the camera. It used a 55 mm wide film derived from the Cinemascope 55 motion picture process.^[11][12] A dozen f/0.75 Baker-Nunn cameras with 20-inch apertures – each weighing 3.5 tons including a multiple axis mount allowing it to follow satellites in the sky – were used by the Smithsonian Astrophysical Observatory to track artificial satellites from June 1958^[13] until the mid-1970s.^[14]

[KP82]

For imaging, there is RASA that fits your short FL SCT requirement. Technically it isn't an SCT as it only borrows the schmidt corrector and the spherical mirror from the SCT but not the folded light path.

As for visual afaik such fast instruments (f/2 - f/3) only exist in the form of custom made newtonians (large dobs).

[Peter Drew]

The Hyperstar compatible SCT series can operate at F2  for imaging.   

[PeterW]

Curved filter..:. There are many good reasons for making filters flat, both manufacturing and use. Optical quality highly curved surfaces are very hard indeed. 
I’m the question for you is focal ratio, which depends on what you want to image, how quickly and how much you have to spend. Short refractors and camera lenses can go quite a long way.

Peter

[michael.h.f.wilkinson]

For imaging there are various solutions, but for visual, an ultra-fast scope really doesn't add anything, except nightmares for eyepiece designers. In theory, a fast scope gives a wider field of view, but that has its limits. Suppose I have an F/2 scope. The very longest EP I might try is a 14mm to reach a 7 mm exit pupil. Anything significantly longer is going to effectively reduce that precious speed and aperture. This F/2 14 mm combination is going to give me the exact same view as a 28mm EP in an F/4 scope, assuming the EPs have the same apparent FOV. This is simply because the same amount of light is spread out over the same apparent field of view, the same solid angle, assuming the transmission through the optics is the same. However, the F/4 scope is likely to be better corrected, needs fewer elements to get the correction right, probably has a smaller secondary obstruction, and the eyepiece can be considerably simpler at F/4, so again, less glass, fewer glass-air interfaces are needed. That all adds up to the F/4 scope with a 28mm transmitting more light, being better corrected, lighter and cheaper than an F/2 scope.

 

Note that for imaging speed is of importance, because the same amount of light is concentrated on a smaller surface area (in square mm). So for a given sensor or pixel size, more light is gathered per unit of time

[Highburymark]

3 minutes ago, michael.h.f.wilkinson said:

For imaging there are various solutions, but for visual, an ultra-fast scope really doesn't add anything, except nightmares for eyepiece designers. In theory, a fast scope gives a wider field of view, but that has its limits. Suppose I have an F/2 scope. The very longest EP I might try is a 14mm to reach a 7 mm exit pupil. Anything significantly longer is going to effectively reduce that precious speed and aperture. This F/2 14 mm combination is going to give me the exact same view as a 28mm EP in an F/4 scope, assuming the EPs have the same apparent FOV. However, the F/4 scope is likely to be better corrected, needs fewer elements to get the correction right, probably has a smaller secondary obstruction, and the eyepiece can be considerably simpler at F/4, so again, less glass, fewer glass-air interfaces are needed. That all adds up to the F/4 scope with a 28mm transmitting more light, being better corrected, lighter and cheaper than an F/2 scope.

I was surprised that the manual for my Tak Epsilon F/3.3 even had a section on observing with eyepieces. Now there are F/2.8 Sharpstars for sale at FLO - imagine that with a poorly corrected eyepiece 

[michael.h.f.wilkinson]

12 minutes ago, Highburymark said:

I was surprised that the manual for my Tak Epsilon F/3.3 even had a section on observing with eyepieces. Now there are F/2.8 Sharpstars for sale at FLO - imagine that with a poorly corrected eyepiece 

Well, if you like seeing lots of little luminous seagulls filling 50% + of the field of view, it would be great

[Robindonne]

Since having seen an eastern clip i often dream about sitting on soft chair between 2 20” f/6 mirrors on a clear night, feeling the tracking motors through my whole body, sailing thought the sky😍.  
 

of course having two eyepieces poking in my skull

Edited May 26, 2021 by Robindonne