Can Tatsuya use Material Burst in the tactical/strategic scale without the Third Eye CAD?

Question

The "Third Eye" CAD is treated security-wise like a nuclear detonator, and custom made by third division of FLT exactly for him use Material Burst effectively.

Is it feasible for him to cast it at that scale/range without it?

Answer 1

Yes, he can maintain strategic class levels of range and potency, even without the Third Eye.

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There are two parts to strategic level magic - range, and strength.

Tatsuya can successfully cast Decomposition on objects with the size and mass of Armoured Personnel Carriers (APC's), and material burst is merely an differentiation of that (the conversion of matter to energy, rather than base elements). A flag of 1kg is the cause of the destruction in Zhènhai Naval Port, so while he would find no trouble in casting Material Burst on something like a car, the destruction caused would be far greater.

Being near the activation point of such a cast would be, as mentioned in Saphiric's answer, suicide. But, this is just hypothetical - Tatsuya has the potential to cast that kind of magic if he wanted to, and that's all that matters for the question.

So his scale, naturally, is still of strategic class even without the Third Eye.

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Range is a more awkward matter.
While it's more difficult for him to activate magic on a strategic scale without the Third Eye CAD - mostly due to the necessity of finding a suitable target - it is still possible for him.

It's important to remember that magic isn't bound to the physical plane, instead using a separate dimension where trivialities like distance aren't issues. Since magic is simply a phenomenon rewriting the data of a specific Eidos (information body) that exists in the real world, as long an information body's coordinates are known, it can be targeted.
Only a very small number of spells (such as Gram Demolition) physically travel through the real world, and therefore only those spells are restricted by physical distance.

Most magicians can't perceive a target more than several hundred meters away, simply due to the limits of the human body.
But, this is Tatsuya. With his Elemental Sight, he can perceive things in the information dimension, or the dimension of magic, where distance is no issue:

This was not looking down from a bird’s eye view, he was looking at things from the point of view of the information dimension. It was not an elliptical sphere around the double focal points, it had nothing to do with physical distance[...]

_{Volume 10 - Visitor II, Chapter 12}

Even so, he can't just pick a random target to cast Material Burst on - he has to know the coordinates of the Eidos. This is the main purpose of Third Eye, to pick targets at huge physical distances, so Tatsuya can easily manipulate them in the information dimension. However, this isn't the only way he can find a target. If he picks out an information body he can perceive at close range and follow it as it travels, he can cast magic on it at any distance:

By his own hands, using the magic he alone could wield, he had decomposed then rebuilt the bullets. However far away they flew, he would not lose sight of their information structure.

_{Volume 8 - Reminiscence,Chapter 16}

As proof of this, the first time Tatsuya uses Material Burst is without any sort of CAD, and he casts it at a target 20km away, one of the aforementioned bullets:

Tatsuya stretched out his right hand towards the west, and forcibly unclenched his palm.

The bullet broke down into energy.

In that moment, the mass conversion magic ‘Material Burst’ was used in anger for the first time.

_{Volume 8 - Reminiscence,Chapter 16}

Granted, it's not quite as far as the distance he casts it in Episode 26 of the anime, but it's still a considerable distance that's far beyond the realm of normal human perception. Furthermore, he states that he could cast it at a greater range, but in this instance, he is limited by the range of the sniper rifle's bullets he uses as a medium to cast Material Burst on:

Sanada’s murmur was drowned out by the boom of the sniper rifle.

Tatsuya’s eyes seemed to chase that supersonic bullet which should never have been seen.

At length he shook his head, disappointed.

"……It’s no good. It could only reach 20 km."

_{Volume 8 - Reminiscence, Chapter 16}

So although practically very difficult to recreate without proper planning and requirements, it is theoretically possible in the right circumstances, meaning his range too, is still that of strategic class without Third Eye.

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In conclusion, yes, Tatsuya can cast Material Burst unassisted at a range and scale similar to that which he achieves in Episode 26 with the Third Eye, but he would require a very specific set of circumstances, and would need to rely solely on Elemental Sight for targeting. That's the main reason for that CAD - to make Material Burst far more practical to cast.

With or without Third Eye, he's still very much "Strategic Class"

Answer 2

In short, he can do it at the same scale, but not the same range.

He can do it at the same scale, however it would be suicide. Magic, according to the novels, requires setting a target to overwrite its current state, which breaks down to being able to see the object or have acute awareness of its existence and state. Since Material Burst uses Einsteins formula to convert matter to energy, even the smallest thing would set off a massive explosion. Knowing that, it is then safe to assume that without Third Eye, activating Material Burst on pretty much anything within the range of naked eye would cause him to be caught in the ensuing inferno.

Third Eye is not required to activate Material Burst, it is essentially a tool that allows him to use Material Burst at a strategic scale without annihilating himself in the process. Third Eye connects to a satellite that then relays images to Third Eye, allowing Tatsuya to then activate his magic.

The information here is from reading the fan translation on Baka Tsuki, which does better at explaining things than the anime.

Answer 3

I would like to add on to the previous answers and make a small correction about the purpose of Third Eye.

The purpose of Third Eye is pinpoint targetting. It does not allow Tatsuya to cast at a greater range, in many sense. Rather, it allows Tatsuya to target a small object accurately from a long distance away. Presumably, Tatsuya can, without the aid of Third Eye, target the sun (and probably fail because the Sun is too big for decomposition).

Sanada, in his evaluation of Third Eye, noted how it was able to target a drop of water many miles away.

Unfortunately, much of the implications of magic and how sight works is not well understood, so the following is just conjecture.

However, it is plausible that he could set a random, far away object as his target. However, he would not be able to know exactly where is the thing he has targeted, or whether or not it actually is far away.

Answer 4

Tatsuya did use material burst without the Third Eye.

That scene at the very start of the first episode, was shortly after Tatsuya used Regrowth on Miyuki and co. They even beat his ass for killing people who surrendered or were retreating after he was told to not do so prior. In that case, without the third eye. Material Burst was theoretical, just like regrowth was when he used it for the first time to save Miyuki's life. When he reassembles an object or person he gains an intimate knowledge of it and it's location. During that first battle, he was attempting to disassemble enemy shells from the warships and use them as a way to use Material Burst. Because the sniper rifle they had on hand wasn't enough to give him the correct accuracy and originally he wanted to use the bullets of said gun. Tatsuya also made mention that if he wanted to, he could make his own Third Eye and even improve upon it.