Back in late 2008, when I built my "facsimile" Galilean telescope, I was amazed... no, make that appalled... at how poor the optic design was. Yet, this was remarkably similar to one of Galileo's telescopes that still exists to this day, in fact better. Was I able to replicate some of his findings? Of course, but the simple fact is telescopes from that very early period were tremendously lacking.
Which brings me to my current work in studying early telescopic sunspot observations.
So far, it appears a typical 17th century telescope has difficulty in finding any small sunspots at all. For instance, yesterday the only sunspot groups that were visible through my regular solar telescope "Beatrix" were AR2259 and AR2261. The former group not only had the larger count (eight), but also the larger spots, whilst the latter was only represented by one, small, visible spot.
"Christoph", my research telescope (50mm f/20, stopped to 25mm thus making it f/40) could only reveal AR2259, and just its two largest components. AR2261 simply was not there. In both configurations, Galilean and Keplerian, When my Galileoscope, the control for this project (50mm f/10, likewise stopped to 25mm, f/20) was mounted in the helioscope, the view greatly improved, though was still a bit lacking. Again, only AR2259 was visible, as were its two larger components. However, not only was the image far sharper, the smaller spots within that groups were on the edge of visibility, as was AR2261, and that in both configurations.
While I know that many serious amateur astronomers tend to deride the Galileoscope and other smaller instruments as either teaching tools only or mere toys, the fact is that they were far superior to what was available to average astronomers for almost two centuries.
These are far from mere toys when properly used.
