Here are two of interest to early photography.

Samuel Morse, more widely known for his (sort of) invention of the telegraph and Morse code was also incredibly important in bringing photography to the United States. His letter of April 20th, 1839 to the New York Observer was one of the first accounts of photography to be published in the United States. By the way it is fascinating to read, just to see how someone would explain photography to an audience that would have never seen such a thing. He also came back to New York and taught many of the first generation of American daguerreotypists having learned himself directly from Daguerre.

William Henry Fox Talbot in Britain, known as the inventor of the negative process and paper printing (the Talbotype/Calotype) was also an accomplished Assyriologist and was one of initial decipherers of cuneiform in the 1850s!

Basically when you start looking into the biographies of figures involved in the early photography scene of the 1840s, it isn't unusual to find they had other pretty remarkable interests and were really scientific or artistic luminaries of the period. Often either they were generally interested in technology like Morse, or their other ventures somehow brought them to photography (like the critic John Ruskin). I think the intersection of art and science attracted many of the 'Renaissance men' of the period.

Frederick the Great was more than just a military genius and a philosopher king. He was also a talented flautist and wrote over 100 sonatas for the flute alone - this in addition to four, just, you know, regular symphonies. This led to some pointed jokes around his palatial estate of Sanssouci, referencing reports of Frederick's bisexuality. Essentially the joke was, Frederick's great at playing the flute because, well, you get it.

I have also read somewhere - but cannot source it now - that Frederick authored some pamphlets pseudonymously and passed them off to his friend, Voltaire, to publish in France. Some credited Voltaire with their authorship, which was said to delight Frederick.

All in all, he was probably the closest Europe came to an enlightened despot.

Dwight D. Eisenhower was a prolific reader of Westerns. The night of the D-Day paradrops, prior to the morning landings, Ike apparently read two or three Westerns while chainsmoking.

Hugo Black, likely the most important Supreme Court Justice of the 20th century, was a huge tennis fiend. He would invite his clerks over to his personal tennis court to play a few rounds whilst discussing finer points of constitutional law. My own professor in law school, A.E. Dick Howard, related to a class that he was frequently winded - in his 20s - by the aging Justice's tennis acumen.

On a related note, William Rehnquist, former Chief Justice of the Court, occasionally dabbled in thrillers and murder mysteries. Have you ever noticed that Rehnquist was the only Chief Justice to bear chevrons on his robes? This was because Rehnquist was a great fan of Gilbert and Sullivan, and deliberately copied costume design from Iolanthe in redesigning the Chief Justice's official garb. (One of Chief Justice Roberts' first acts as Chief was to remove the gold bars from the sleeves of the robes.)

Herbert Hoover, in addition to being a proficient engineer and fluent in Mandarin, was also obsessed with geometry. His presidential "doodles" - while looking somewhat haphazard - were often variations on Euclidean or Ptolemaic propositions. http://cdn.theatlantic.com/static/coma/images/issues/200609/doodles/ur_doodle_psweb.jpg

John F. Kennedy, along with his brother Bobby, as well as Henry Kissinger, were all fans of the classic table game "Diplomacy." Oddly fitting.

Eamon de Valera, in addition to being the longest serving head of state in Ireland's history, had a fondness for rugby and calculus, spending some of his time while imprisoned by the British tangling with complicated calculus proofs.

The British PM William Gladstone was a famous Homeric scholar who undertook a personal quest to explain color discrepancies within Homeric texts. His conclusions were discussed in a recent Radiolab episode.

James Longstreet, Lt. Gen. of the Army of Northern Virginia, was probably the Civil War's best poker player (among the general officers, I mean), but lost his fondness for cards after the deaths of three of his children within a week due to scarlet fever.

Heinz Guderian and W.T. Sherman, besides being historic military leaders, were also proficient in quoting Shakespeare, and both used Shakespearian quotes or allusions in their memoirs.

Louis XVI of France has been for years described and caricatured as a simple mind by many until last century's historians started giving much more credit. Most people know him for his fate, his wife and the Revolution but I've realized that a huge number of people ( amongst non-historians ) never heard about the fantastic mind that he was. A very well learned man with hobbies other than hunting.

Louis XVI was a locksmith and clock-smith. These are maybe his two better known center of interests. In Louis XVI, le roi bienfaisant, Jean de Viguerie also says that he had a certain talent for architecture. He liked to draw plans for buildings and such, even if it was to rip the paper apart just after.

The King also liked to learn languages, this due to his father's strict education ( his father actually certainly spent more time sitting and reading than walking and as such punished the future Louis XVI from going outside or hunting if he did not study well enough ). He was perfectly fluent in English ( reading, writing and speaking ), translated British books and read their newspapers. Of course he speak and read Latin but German and Spanish as well. Louis was also a greedy reader, taking care personally of his library. I learned that today, but Bernard Vincent in his biography ( Louis XVI ) says that when he was locked in the Temple's tower, he read 257 books, from Montesquieu to newspapers, he read everything.

Then one of his other hobby and certainly one of the most interesting was everything surrounding the navy, maritime matters and exploration. His reforms of the navy also show the paradox that Louis XVI was. Like his predecessor, he loved the idea of eternal peace and a pacified world ( or at least a pacified country and Europe ) but gave the means for the navy to outclass the British Navy. His ministers kept him informed of every reform made in the navy's administration and organization, Louis gave his own advises and suggested a better use of French spies in Britain ( every British ships had been observed, detailed and classified with their manpower, fire power,...Etc ). This proved extremely useful during the American Independence when the French Navy regained some of its prestige proved a decisive element in the war. Exploration and maps were also something that interested Louis a lot. He organized himself the expedition of Jean-François de La Pérouse to sail around the world, contact the indigenous peoples and map the Pacific Ocean. He invested himself so much in the project that he even gave his opinion ( and sometimes order ) on which captains to appoint, which explorer to mandate,...Etc It is even said that while walking to his place of execution, Louis XVI asked if there was any news from de La Pérouse ( he did manage to convince the new Revolutionary Government to organize a second expedition in order to find what happened to La Pérouse ).

Not too bad for someone who never traveled much outside Versailles and Paris.

I would recommend to anyone reading French ( because I don't think it is translated ) the amazing book of Bernard Vincent called Louis XVI. It is about his last days and with a great description of him as a person ( it's more about the person than the monarch ). Simply fantastic book.

Henry VIII is mostly known for his many disastrous marriages. Besides being incredibly learned on many subjects, which I'lll expand on below, he was also talented at an almost puzzling array of skills. He was truly a "Renaissance Man" and would likely have been remembered for his many talents and scholarship if not for his unfortunate marital life. Though contemporaries may have exaggerated his talents for various reasons, it has been generally accepted that Henry VIII was legitimately an expert and/or visionary in several studies, including: music (and composing), writing (theology and poetry), ships and naval warfare, and several other active pursuits such as jousting and hunting. (Will return later with sources and examples if requested.)

It was common in the past for Rabbis to not make their living, well, being Rabbis. Quite a few of them had day jobs as well. It's fairly well known, I think, that Rashi was a vintner, even though he never achieved much significance in that field. There's reference in the Talmud to Rabbis being brewers, tanners, etc.

But Maimonides in particular was actually quite significant in his other field. He was a doctor. He wasn't the only Rabbi so employed--one of the other big names of Spanish Rabbis, Nachmanides, was also a doctor. However, Maimonides was a pretty reknowned doctor, apparently. Besides being the sultan's personal physician in Egypt, he also wrote several medical texts which survive to this day.

It's not like it's totally forgotten, but when people think "Maimonides" they think "Rabbi and philosopher", but he also was a pretty accomplished doctor.

The novelist Vladimir Nabokov (author of Lolita) was a prolific amateur lepidopterist (entomologist that studies butterflies and moths). He wrote extensively on the subject and has theories that are just now finding some recognition. It should be noted though that he also believed that the study of the genitalia was the key to understanding the origins of butterflies and not genetics and chromosomes. Because of his work the genus Nabokovia was named for him.

Many of the founding fathers were interested in natural philosophy. Everyone knows about Franklin and his kite, but he wasn't the only one. For example, there was a controversy in the late 1700's about the relative "quality" of new and old world animals. A prominent French natural philosopher, Buffon, claimed that life in the New World was inherently small and weak. Thomas Jefferson was eager to disprove this nonsense claim, and to aid him in this Madison sent him a detailed record of a weasel from Virginia, complete with measurements down to the size of the genitalia. Jefferson also went out of his way to ask other political notables to send him a big impressive stuffed moose to show Buffon while he was in Paris, and finally got a somewhat disheveled one from the governor of New Hampshire. If only Teddy Roosevelt had been around then, I'm sure he would have been able to secure a more impressive specimen.

All this comes from Dugatkin's Mr. Jefferson and the Giant Moose.

Oh, and another fun fact, this one about Teddy Roosevelt. Not too long ago, someone was analyzing old museum specimens and reports from South America and realized there was an entirely new distinct species of tapir among the specimens (and also considered distinct by the local people). The type specimen for this species (the original "definitive" one used for classification) turns out to have been collected by Roosevelt, who actually shot one and noted at the time that it was distinct from the other species.

You can read about it here