Posts Made By: Roland Christen

Sorry that I have to do that. The 600 mount is extremely difficult for us to machine and assemble, and we were basically losing money on every one we made. It is not very easy to adjust in the field if something should go out of wack.

The mount is more than 15 years old now. It definitely has run its course, and there are better ways to make mounts today. We want to take advantage of new thinking and new technology, and to beef up the weak spots in our products.

Thanks for letting me explain.

Rolando

That is one cool image!

RC

There are no advantages of this design over more conventional systems that I can see except perhaps the very shortness of the assembly. However, are SCTs not short enough as it is?

Roland Christen

You're really getting the most out of that 9.25" aperture .

Roland Christen

Here's a pix of the instrument

RC

Forgot to say that is is a 14" F4 mak-Newt.

Roland Christen

You can screw the AP 2" convertible Barlow into the front of the Baader Bino. It provides approximately 2.3x in that configuration.

Details are on our web page under Baader Accessories/Binocular viewer. Scroll down and bring up the Assembly diagram. On the very top of the diagram it shows how to attach the 2" Barlow optics (item 10a) right to the front of the Binoviewer.

Roland Christen

>>It would be interesting to put a 9.25 up against, say, a 10" high-end reflector in the f/6-f/7 range, and see what conclusions are reached for visual use on planets, lunar, and doubles>>

If you're talking visual, I would put my money on a high end reflector. Reason is Central Obstruction. Two years ago I brought two high end 10" Mak-Cass scopes down to the Florida Star Party. One was an F9 with 31% obstruction, the other an F14.6 with 23% obstruction. The scopes were set up side by side. On things like delicate detail on Jupiter, you could see the difference quite readily in the amount of subtle detail and contrast visible. When we aimed both scopes at Sirius, the companion was easily visible in the 23% F14.6 obstructed scope, and very difficult in the 31% F9 scope.

The C9.25 is even worse than 31%, something on the order of 38%, I believe. As such, it would not stand a chance against a well made high end Newt with 20% or less obstruction.

Just because there are great images coming out of this scope does not mean that you will visually see this kind of contrast and detail with your eye. In order for the eye to discern subtle detail the inherent contrast must be very high, and a largish central obstruction will definitely kill it real quick, no matter how well the optics are figured. An imager can stack thousands of images and crank up the contrast until even the minutest detail pops out. There is no such contrast enhancement feature in a human eye/brain system.

Roland Christen

By the way, what's the apostrophe doing in sct's?

RC

>>How much better would be a 5" fluorite doublet if the mating element would be optimally chosen for optical quality of the objective instead of putting priority on the ease of production (Tak example). Would there be e.g. noticeably less "warmth' in the picture >>

If you are asking the general amateur public, you will get all kinds of answers that are uninformed at best.

The reason any apo doublet has a "warm" color is quite simple. The design allows some blue color error in order to achieve high production capabilities. In order to make the production straight forward with modern machine polished optics, the two elements have to be chosen so that their natural melt variations do not cause large differences in the color correction. This naturally limits the range of full color correction to a smaller value. Blue-violet being the hardest to bring in, it is allowed to fall outside of focus and thus the image is deprived of this cool color, resulting in a "warm" appearance. Since there is little information in the bluest wavelengths on planet surfaces, most people don't see the difference (except for the purists, of course).

Yes, one can make a doublet with no visual color error, but it requires having to match each set of lens elements individually with slightly different curves. Beyond a certain point in the wavelength range, a doublet of any kind, whether fully corrected for color or not, will have enough sphero-chromatic error that it is limited by that aberration. In other words, even if the ends of the spectrum have zero color error, the spherical error will begin to dominate.

With three lens elements, one can extend the range of perfect focus far beyond the visual into the region where CCDs still have quite high sensitivity. So for imaging, a triplet will have certain advantages. They stay sharp over a much wider wavelength range than any comparable doublet. For visual, it is not readily apparent.

Roland Christen