Planetary resolution with P900/P950/P1000

Started 3 months ago | Discussions thread
OutsideTheMatrix
OP OutsideTheMatrix Senior Member • Posts: 7,426
Re: math back up

I visited various sites and found figures for all three features. It is also interesting to note that Cassini's division was discovered by Cassini using a telescope with a 2.5" objective diameter at 90x magnification. The P900/950 lens has a 2.16" objective diameter and has 83x magnification. That is a pretty close match! Of course Cassini made his discovery in 1675 so this is almost 350 years later lol.

Cassini's division is 3000 miles wide

Great Red Spot is 10,000 miles wide

The Northern Martian Polar Ice Cap is 700 miles wide

The Southern Martian Polar Ice Cap is 250 miles wide.

At all of their closest approaches, Saturn is 2x farther than Jupiter and Mars is 22x closer than Saturn.

The listed angular diameter of Cassini's Division at closest approach is 0.75" (seconds of arc.)

It is about 2800x smaller than the full moon. Since the full moon also covers about 2800 pixels that means the 0.75" seconds of arc diameter of Cassini's division should cover almost exactly 1 pixel on the P900/950 at 2000mm EFL (no wonder Dynamic Fine Zoom is needed to give it more clarity- and I wonder if stacking would add to clarity.)

Based on the above numbers, Cassini's Division is clearly the smallest in terms of what it looks like from Earth. Jupiter's GRS looks about 7x wider (3.5x larger AND 2x closer) and Mars' Northern Polar Ice Cap looks 5.5x wider (22x closer makes up for being 4x smaller) while the Martian Southern Polar Ice Cap looks 2x wider (22x closer makes up for being 12x smaller).

I did some calculations using the diameter of the Martian Polar Ice Caps (north - 700 mile diameter, south - 250 mile diameter) and the GRS (10,000 mile diameter) using closest approaches of Mars, Jupiter and Saturn and setting the Cassini Division as the reference point at 3,000 miles wide and 0.75".....at the closest approach of Saturn, if the GRS was located there it would be 5,000 miles wide (using 2x closest approach distance of Saturn vs Jupiter).... so the GRS is 3.5x larger and 2x closer (which means it should have an angular diameter of 7x that of the Cassini Division when viewed from Earth) Mars Northern Polar Ice Cap although only 700 miles wide, Mars is 22x closer at both their closest approaches but only 4x smaller.....in the case of the Southern Polar Ice Cap it is 12x smaller. Even using the smaller ice cap numbers, it should have about twice the angular diameter of Cassini's Division when viewed from Earth and with the Northern Polar Ice Cap it's more like 5.5x the angular diameter of the Cassini Division.

So, in summary, if the maximum angular diameter of Cassini's division is 0.75" then Mars' Southern Polar Ice Cap is about 1.5" and the Mars' Northern Polar Ice Cap is 4" and the GRS on Jupiter is 5.25" Cassini's Division is clearly the most difficult to resolve so if it can be resolved so can the other features. If we set the width on our pictures of Cassini's Division at 1 pixel at Saturn's closest approach (at 2000mm EFL), then Mars' Southern Polar Ice Cap is 2 pixels wide and Mars' Northern Polar Ice Cap is 5.5 pixels wide and the Great Red Spot on Jupiter is 7 pixels wide at their respective closest approaches.

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Olympus C-7070 Wide Zoom Fujifilm FinePix HS20 EXR Fujifilm FinePix HS50 EXR Fujifilm FinePix S9900W Nikon Coolpix P900 +9 more
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