Will the difference between an achromatic, semi-apo, and apochromatic refractor be noticeable? We test some small refractors by photographing a simple daytime target.

If you're confused about the difference in optical design of refractors vs reflectors vs SCTs vs Maks, etc, this table summarizes some of the key points

If you're considering buying a 40mm Plossl, read why we'd recommend getting 30mm Plossl instead. 

If you're baffled by all the different mounts offered by different vendors, here's a table that may help you sort them out.

Some equatorial mounts are unusable in equatorial latitudes due to design limitations. Here's a list of known mounts that fall in this category

If you're considering buying a unit power finder (i.e. it doesn't magnify the view), then do consider either the Telrads or the Rigel Quikfinders. The pros and cons of them are reviewed here.

If you're considering buying a filter for viewing DSOs or for astrophotography, read this for a quick summary of what to consider. Also includes a section for colour filters and what they can enhance for planets, moon, and comet views.

What are Tidal Forces