Images of 16th century warfare includes fully plated Christian nobels. Yet images of Janissaries or Sultans tend to focus on chain mail and what an unelightened mind (like mine) would call fabrics. But this can't be correct, can it?
I'm very suspect of how accurate these western images are as it seems unusual that ottoman forces would wholly prioritise mobility over protection, especially when we are talking about Visiers and Sultans.
I do understand that it is possible to wear chain mail under fabric clothing or weave plates into clothing.
Would highly recommend we all read articles like this one from the MET. Per my own limited knowledge, I would assert that the Ottoman, and Middle Eastern militaries in general, fought more often in comparably light cloth or chain/lamellar armor, relying less on heavy armor of their West European counterparts.
The Ottoman military’s general unit types show which armor types would be needed. Light cavalry azaps and Tartar horse archers rarely wore metal armor at all, relying on ambush and operational raids, not heavy cavalry charges with spear and shield. Volunteer jihadi bash bazouk fought in light armor and were preferably used for sieges. There were ‘heavy' cavalry cores of mounted sipahis from the Rumelian and Anatolian provinces, and a comparably small infantry core of janissaries. Neither generally opened the battle or fought in heavy steel plate, except Serbian and Hungarian levies of the Rumelian Balkan provinces who are reported to use West European armor. Surviving examples of Anatolian and Janissary armor show ornate, and quite effective use of lamellar, mirror plate pieces tied to cloth or chain mail, and of course, literary sources report heavy use of silk and cloth ‘armor’. The Janissaries appear to have placed a higher premium on defensive firepower and offensive courage than heavy, exhausting armor.
The professional Ottoman military of the 16th CE generally placed a higher premium on durable unit tactics, firepower, élan, and maneuverability. Keep in mind too that shock troops don't necessarily need heavy armor to act effectively on the battlefield. Philip of Macedon and the Swiss pikemen alike fought without any armor, giving their men an ability to move fast and deliver heavy blows with longer pikes and pole arms. Similarly, many of the best cavalry in Eurasian warfare placed a higher premium on long lances rather than scale or plate armor. Plate armor in many ways is an ineffective weapon in any battles lasting longer than a few minutes. Plate armor acts as a heat sink, which matters less in battles in England perhaps, but immensely in battles in Asia.
Light armor did not seem to detract from the Ottomans' tactical efficacy in 16th CE battle, particularly as the Ottomans (by contemporary standards) made exemplary use of combined-arms tactics which would wreck the momentum of any European heavy cavalry.
(1) In small skirmishes, Ottoman azaps and Tartar horse archers would appear with a dash and a whirl, fire volleys into the enemy ranks, retreat if approached by enemy cavalry, and basically act as a nuisance. The intention was to kill horses and isolate individual enemies, leaving them vulnerable to any high momentum mace or scimitar attacks. Contrary to occasional Reddit gamers idolizing the horse archer, the tactic alone was often ineffective against heavy infantry or cavalry who maintained discipline and brought at least a few units of infantry archers/gunners along.
(2) In large set-piece battle, the Ottomans would generally use more infantry but once again play a defense-in-depth, with heavy use of bashi bazouks to soak up the momentum of any enemy charge, second rank janissaries using field defenses and firepower to overcome a truly effective charge, and comparably heavy cavalry reserve ready to swoop in and deliver a flank attack when needed. Neither of these tactics require heavy infantry or cavalry to hold the line or charge equally fresh enemies. The main goals are effective reconnaissance, ambushes, showing up to set-piece battles with more men, using maneuverability to weaken enemy formations, and melee combat only as a last resort by fast cavalry capable of retiring and renewing multiple attacks.
Against these tactics, West European armies, particularly heavy cavalry wearing plate armor, generally seem to have ended up disorganized, exhausted, and with blown fatigued horses. That being said, (admittedly European) sources also report how important heavy cavalry plate and chainmail armor, such as that worn by the Serbs at Mohacs, could be when the Ottomans prematurely entered melee combat against comparably fresh European cavalry. Both weapons systems had their moments, provided they were used intelligently by good leadership who understood the costs and benefits.
Sources: Turnbull: The Art of Renaissance War; John Julius Norwich: the Four Princes