I've been thinking about taking a photograph of Saturn with its rings,
but it looks like doing so might be quite difficult without some
proper astronomical equipment. I posted an old photo I took of the
Pleiades with maximum zoom, 70mm, and a too long exposure:

http://www.flickr.com/photos/sbp/4486577116/

And then ran that through the astrometry.net group annotator to get
the arcsec per px value. Ignore the "70.42 arcsec/pixel" result,
because that's using the smaller size photograph. The width of the
original is 3875px, and astrometry.net gives the field size as "20.03
x 13.42 degrees", so the actual arcsec/px value is:

<sbp> .c (20.03 / 3875) degrees in arcseconds
<phenny> (20.03 / 3875) * degrees = 18.6085161 arcseconds

I found a good picture of the moon to scale with Saturn and Jupiter:

http://www.clarkvision.com/astro/moon_saturn_jupiter.d60.v1/index.html

And this is annotated saying that it's 2.1 srcsec/px, though the moon
is 1800 arcsec:

"The angular diameter of the Sun is about the same as that of the Moon
(the ... from earth is about ½ degree, or 30 arc minutes (or 1800
arc-seconds)."
- http://en.wikipedia.org/wiki/Angular_diameter

And the moon in his photo is 811px wide, so the actual value is:

<sbp> .c 1800 / 811
<phenny> 1 800 / 811 = 2.21948212

So to get the same kind of scale as my camera:

<sbp> .c 18.6085161 / 2.219
<phenny> 18.6085161 / 2.21900 = 8.38599193
<sbp> .c 926 / 8.38599193
<phenny> 926 / 8.38599193 = 110.422238

You have to reduce the clarkvision.com image to about 110px wide:

http://imagebin.ca/img/vwZRdQBU.jpg

Which makes it hard enough to see detail on the moon, let alone the
rings of Saturn. The moons of Jupiter are barely visible too, though I
suspect with a long enough exposure they might be visible. I also
found a page about observing the rings of Saturn through binoculars:

http://www.thedas.org/dfiles/eastman_saturn.html

And again the general indication is that the rings aren'r really
visible, unless you have good equipment and conditions. I have taken
terrestrial and celestial photos through a telescope before, so I know
that it's possible without having an adapter. It would be pretty funny
to get a good photo of Saturn through a telescope with a hand held non
mounted camera.

Wikipedia points from its Saturn article to a fun paper which
indicates that an old Indian treatise had good knowledge of the
diameters of the planets, which the author suggests may be based on
lost ancient astronomical knowledge:

http://www.scientificexploration.org/journal/jse_11_2_thompson.pdf
Thompson, Richard (1997). "Planetary Diameters in the
Surya-Siddhanta". Journal of Scientific Exploration 11 (2): 193–200
[193–6]. Retrieved 2010-03-13.

But in fact the tract doesn't give diameter specifically, but angular
widths and distances, from which the diameter can be computed. It
turns out that the widths and the distances are extremely inaccurate,
but at such a ratio which gives approximately accurate diameters, so I
think there's some fudging going on here. One interesting thing that
the paper mentions is that pre-telescopic estimations of the angular
widths of the planets were very inaccurate because bright almost point
sources naturally look wider than they really are.