I found this on another site and it goes into a bit about why Ottoman involvement was limited.
First of all, the Ottomans were not the all-strong and mighty Ottomans of 16th century...While being the world's most powerful empire together with Karl V's Habsburg Empire at that time, this great status was no more in the 17th century...Of course, they were still one of the strongest empires of the world, but not in the same way&glory it had in second half of 16th century.
Ottoman treasury was empty...The new trades routes were found and formed after explorations of 15th&16th century,Silk Road and Spice Road lost their importance...Moreover, the conquests, which was an important part of profits Ottoman treasury was getting, stopped...Empire reached its natural maximum borders..It wasn't able to annex vast lands anymore...The conquests were just limited to single fortresses or small land portions instead of 15th&16th century conquests(which costed more than it would bring, this treasury had been especially got empty in Suleiman I era due to long and huge expeditions over different regions), in which whole countries were annexed into the empire..The administration of the empire was getting harder everyday as it had grown too much..Ottoman science was starting to progress behind their European counterparts, as important given to all kinds of sciences had fallen and the
"ulema" group, which consisted of people related to religion increased their influence, together with the Janissaries and Kapikulu soldiers(the stable army of Sultanate other than Spakhis), and those two got into administration and had been more influential in state politics even more than the sultan himself...They even hanged reformist sultans like Osman II..In addition, the new sultans and statesmen rising were not capable and influential, and couldn't exert control over those ulema and soldiers.And due to brother killings to get the full control as Sultan, when a Sultan died, the new Sultan passing over to the throne, had been just 6-7 years of age, and the control of the throne had fallen into the "Valide Sultans", the mothers of the sultans, together with the influential statesmen and army/ulema duo.
Corruption began and the "tımar" system inside the empire was disrupted.The Anatolian Turks, who became weary of poor conditions they had in the empire in contrary to the priviliges given to the Christians inside the empire, rebelled, intensively.This was the general policy of the empire...The Christians were rich, and empire had founded its economical system upon the capital they had, while somehow repressing the Anatolian Turks by not giving good life standards to them in contrary to Christian "tebaa"(folk) of the Ottoman Empire..The empire took some kind of a backward step..
So, what was the Ottomans doing at that time, during the 30 years War?
The Ottomans always used the strategy of supporting Protestants over the Catholics, as their natural and most powerful rival was the Habsburg Empire of Karl V...Remember some old examples...Ottomans supported French in their war against Habsburgs by attacking from the east at the same time French were attacking, saved French king Francois I out of captivity, and even bombarded some Italian cities together with French navy.And they were also supporting the German Protestants, naturally as they were malicious to Habsburg Empire.
So,we saw that Ottomans were supporting the Protestants, so what caused them not to be active in 30 Years War then?
A few elements we can list out there:
1- The internal rebellions..Anatolia was totally rebelling at the time, full of rebels going to the mountains, as state wasn't just towards them..Ottomans tried to repress those rebellions, but there were basically too much of them everywhere,and repressing them took too much of empire's effort,and they had continued all 17th century long.
2- Administration of the Empire...Empire wasn't controlled by Sultans at all...So, there wasn't that single&autocratic&wise&powerful mind to administrate all the empire and giving all the decisions...For example, in the reign of Murad IV...He just ascended to the throne when he was 6-7 years old, and till he had grown up, and the empire was majorly bound to Valide Sultan K�sem(Murad's mother)'s decisions.In addition to army,ulema and statesmen influences..And it was like an era of intrigues inside the Ottoman Empire.Other Sultans ascending to the throne,in addition to Murad IV coming as a child was not capable, and even not healthy psychologically(like Deli(Mad) İbrahim who reigned between 1640-48)...Osman II, who reigned a short term between 1618-21, was a wise reformist who wanted to take Ottoman Empire into its former days, and when he began reforming against the army, he was hanged by the Janissaries.So, it was the most unstable time of the Ottomans, with all that struggle of power
3-Other enemies: Safavid Dynasty...Ottoman Empire, even though all its might, had a real strong rival in Iran...Safavid Dynasty...It had been kind of a Shiite&Sunnite clash between them till Selim I's time...And in Suleiman I's era, it had escalated to an active huge scale long-term war...After 1603, when Abbas I was on Safavid throne and they were having bright days,the endless war between two sides began again; in many fronts, Azerbaidjan,Iraq,today's Southeastern Turkey and Northwestern Iran... This time to be lasted for 36 years till 1639 Treaty of Kasr-ı Shirin,with short term cease fires...So, together with rebellions, this took main core of the Ottoman effort.And Ottomans had no power to exert pressure and send armies over to the West, in which was a complex situation, and it was a great time for Ottomans to make new gains, and even weaken Habsburgs to a certain extent...They just stayed peaceful(to Habsburgs' benefits,too,of course) and protected their borders...And to be added, Ottoman-Polish wars during Osman II's era, which ended with Ottoman disaster in front of Hotin fortress, partially due to lacklustre of Janissaries and stable army of empire.But after then, Osman II died and empire was burst into instability inside.
And what about the navy?It didn't have that former glory either, and the ships weren't a match for the vessels that the Ottomans' counterparts had...So it was passive most of the time, till 1643, when the siege of Crete began, only to be ended in 26 years...
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