On Jan 10, 9:59*am, "I.M. Yerkinov" wrote:

What is the minimum aperture needed to see surface detail *on Mars?

While some details can be seen with smaller apertures, I would agree
with Brian's suggestion that you would most likely want to consider 4-
inches as a practical, minimum aperture. A *high quality* 5-inch
telescope on a solid mount can provide some very nice views of Mars.

I just came inside from a quick observing session with an inexpensive,
mediocre quality, 80mm f/5 achromat. Some details were visible at
105x, but it would have taken me a while to put those details on paper
with any degree of accuracy. The details visible with this telescope
were neither "sharp" nor easy to pinpoint in position (It didn't help
that I was using the scope on a 'quick look' alt-az mount designed for
low-power use). Filters such as a #23A Light Red can be quite helpful
if for no other reason than to reduce the planet's brilliance. I
found it significantly easier to see details with the ST-80 when I
used the Light Red filter.

Whenever one speaks of minimum aperture, it may be worth noting that
increased observer experience and higher telescope quality can lower
the limit, while decreased experience and lower telescope quality can
result in a need for greater aperture.

Bill Greer
To sketch is to see.