Ok... It's best if I just share my thoughts with all you (I hate having secrets and undesirable feelings that can change my mood).
I understand that every single of you are just trying to help me by saying anything that could lead me to make the best choice, even if it gets off topic (slightly or not). I fully understand that.
I knew there was a good chance of my thread's topic could lead to off topic arguments, because I examined some of the threads in various sections of this forum before registering to measure the maturity and experience level of its users and how they tend to react when giving away their opinions in subjects they believe to be deeply experienced with. There are many users here with a good deal of experience in photography within a wide age group. So I can say I saw this coming. But sometimes getting off topic might not be the best approach. Sometimes is just best to stay close to the subject as possible.
My first response was from RailphotoG asking myself if I would really want to extend my camera's zoom capacity since for him 840mm on his sx30 was quite enough.
Then I got another post from the same user suggesting me to do the obvious. The time I would research the web for a photography forum and to register on it would be more than enough to drop a line at youtube asking about what I did over here.
The second user, Destin, suggested me something that I only realized after his second post it would be impossible to do since it was related to a DSLR camera. I did mentioned I owned a bridge SX40.
Big Mike is was the third user. He gave away a tip (that I honestly believe everyone is familiar with) which unfortunately was not connected with the thread's topic.
Warkw was next, the with a huge post count. He needed to make a statement and the biggest one, like a moderator, trying to convince me that cropping is somehow related to the "Best Telephoto lens converters for Canon sx40" and that the previous post was within topic boundaries. And finally we have DiscoJoe, reinforcing the idea of Big Mike.
So it is clear that no one was in topic. And the proof of that is that my topic remains to be answered. I really don't care about image quality or cropping, all I care is knowing what telephoto lens are there, which ones can be used in sx40 and what would be the best one. If you don't have the answer for this simply don't post anything. It will save everyone's time. Whenever you see a thread created by Endorya, please make sure your arguments are connected to the thread itself. That is, if you are willing to say anything, naturally. I will thank you in both cases.
I hope I didn't cause any hard feelings simply by opening my mind with you.