[jase (Jason)]

Originally Posted by Gama

If any one is going to spend big bucks, then you would know what the specs say and do including the spot diagrams. Posting a Spot diagram from the 2 scopes will mean nothing to the normal person off the street, but to a university or professional, that is one of the main things that stick out the most.

But this is part of the problem. Lack of understanding and too much marketing blurb. If the normal person off the street took greater interest in optical statistics/measurements, all marketing buzz words are removed from the equation. One has to simply browse through the astro mags to be dazzled by crap. Statements such as “Company X is proud to introduce a revolutionary coating system that outperforms any other coating in the commercial telescope market. Our most popular Schmidt-Cassegrain telescopes are now available with this high quality optical coating at an incredible value.” – What the? Am I supposed to believe this? Marketing blurbs mean nothing without sufficient optical data to back such statements up. Unfortunately, obtaining this information is difficult, certainly from the commercial manufacturers.

Originally Posted by Gama

This whole point about the RCX was not that the RCX is a better scope, just another optical system that performs well, not that its better than an RC..

Understood. There are many optical designs out there that perform well. Designs are shifting. As I mentioned in another thread, we are beginning to see optical designs starting from the focal plane forward (instead of the conventional telescope back). With the rise and increasing availability of large format cameras, it makes perfect sense that this shift is occurring. Understandably astrophotographers get annoyed when they’ve payed large dollars for a 35mm+ CCD chip, only to find that their telescope optical design restricts the light path or aberrations are present.

Originally Posted by Gama

It also doesnt matter were any data was obtained to descibe the pros and cons to the different optical methods, the point is its true. Which do you believe to be incorrect ?. To say that the RC's are the best optical scope is easy but i havent found any data that says its better than a CDK, if there is please let me know, as i havent been able to find much to say this..

There are pros and cons with every optical design and again the selection criteria are based on application. I don’t doubt that the CDK is a solid optical design and it would appear there are optical statistics available partly confirm performance; however there is simply not a large market presence to validate these claims. As you mention in your previous post – how a telescope performs in a lab environment can be different to the real world. There are so many variables to consider. The RC install base is large with a real world clear and proven performance record. This of course doesn’t mean the design is the best.

Originally Posted by Gama

The cheaper RC's which are being released, do not perform as good as the current RC's, and if you know RC's, then collimation will be a bigger problem with the cheaper versions.

Of course the cheaper RC’s don’t perform as well as the professional RC series. You pay what you get. The ion-milling process of the professional series isn’t cheap - http://www.rcopticalsystems.com/ionmill.html
Collimation will affect the performance of any Cassegrain. I do acknowledge that many underestimate the importance of collimation especially with these scopes. The collimation characteristics between the RC Astrographs and RC professional series is identical. Seriously, the difficulty in collimation of the RCs is overrated. Its not hard. If you’re purpose is solely imaging, you will not find a better way of squaring your optical axis to your CCD camera by using CCDWare’s CCDInspector.

Originally Posted by Gama

Not much point in talking about the designs if you dont believe there is a better optical system. You didnt comment on the Quoted comment post, as that was also posted at another person who also believed that RC's were the the greates on the cloudynights forum, id like to know your views on it.

You can’t admit defeat. This is a healthy and informative debate. I don’t believe RC’s are the greatest, however I’ve yet to see another design with a proven optical record. As I stated in my previous post, if there is greater optical design, why aren’t we seeing more installations of it? Perhaps over the next decade we will see the emergence of more CDK’s or other RC designs such as BRC.

Originally Posted by Gama

Something also you may not know, you dont need the corrector at the front of the SCT type scopes, it can actually be placed further down the optical train.

Indeed, you are correct. However this is not practical with the SCT design. When you look at ray-traced light paths in such a design, the corrector lens close to the focal plane needs to be large for the correction to occur. Depending where the lens is located, it may require an oversized baffling tube which inturn would affect primary mirror diameter/light gathering power.

Originally Posted by Gama

I agree with you the RC's are a magnificent scope, and it does have its pros and cons, as do all things on earth. But i looked form many months for my next scope and the RC was bumbed off by the CDK. Up until then it was on the top of my list. I am open to any data you have to show me a better optical scope, and possible save me (Or cost me) money.
One other optical system was also the Newt with a corrector, this is also high on my list of scopes.

I’m far from a “telescope consultant”, but you have not alluded to your application. What do you want to do – “pretty pictures” (wide, narrow, deep, hi-res etc) or make the next scientific discovery. You appear to have done all your research and if you’re true to your word, then I look forward to seeing the results of your CDK. After all, it takes people like yourself to make that step, similar to what Steven did with the Allira 14”. I’ve seen about three sites that provide astro images taken through the CDK optical design. It does appear a strong performer. Still no definite Strehl ratios forthcoming so I remain reserved. I'm happy for you to surprise me.