Our Gemara on Amud Beis describes the qualitative difference between Moshe’s prophecy and other prophets:

וָאֶרְאֶה אֶת ה׳״, כִּדְתַנְיָא: כׇּל הַנְּבִיאִים נִסְתַּכְּלוּ בְּאַסְפַּקְלַרְיָא שֶׁאֵינָהּ מְאִירָה, מֹשֶׁה רַבֵּינוּ נִסְתַּכֵּל בְּאַסְפַּקְלַרְיָא הַמְּאִירָה.

The Gemara resolves the first contradiction: “I saw the Lord” is to be understood as it is taught in a baraisa: All of the prophets observed their prophecies through an [aspaklaria], However, Moshe our master observed his prophecies through a clear looking glass, 

Let us try to understand this better.  What exactly is the term, “Aspaklaria”?  It is a word of Greek origin, whose root is “Spec”, which means “to see”, as in-SPECT, or as-PECT, or SPECTator.  One has to be careful with Greek words in the Talmud, as they can often undergo as many changes in meaning, as analogously we find from German to Yiddish. Jews will take a secular word, but then use it within their culture and frames of meaning that are relevant to them. 

The Mishna (Keylim 30:2) discusses an object, also described as an Aspaklaria. Tosafos Yom Tov offers two possible interpretations.  Either it is a mirror, or some kind of looking glass.  

Telescopes were not invented yet, but they might have used various shaped glass as windows or possibly have discovered their utility as magnifiers. (A telescope or microscope uses two lenses, and I do not think that technology was invented yet.  And do not cite me the Gemara Eiruvin 43b as referring to a telescope, as it is actually referring to a sextant.  The Gemara says, “Rabban Gamliel had a special tube through which he would look and see a distance of two thousand cubits on land, and also determine a corresponding distance of two thousand cubits at sea.”. Tiferes Yisrael (Boaz Keylim 30:1) rejects the idea of it being a telescope as preposterous.)

In any case, the metaphor is similar.  Either by means of a mirror, or by means of glass lense, other prophets had a blurry, dark-tinted view, while Moshe’s vision was clear and without any occlusions. Since it is merely a metaphor, the exact nature of the Moshe’s clarity versus the other prophets’ is open to discussion.

The Maharal (Gevuros Hashem 5:47) offers an original idea about Moshe’s prophecy and perception, based on a Midrash (Yalkut Shimoni 147:1). The Hebrew word, “Az” “Then” is often used in regard to Moshe (See for example, Shemos 4:26, 5:23, 15:1, and Devarim 4:41.)  Maharal notes that this word has a bi-valent connotation, simultaneously meaning “then, in the past” and “then, in the future”.  This is Moshe’s otherworldly gift, that he could stand outside of time.  To see Hashem with clarity one must be able to step out of time, as that is closer to the “domain” that God occupies, although of course God cannot occupy any domain as that would be limiting him to a physical sphere.  That is exactly the point, because Moshe had the ability to shed his temporal mooring, he could comprehend God’s will and message in multi-valent ways.  This is only logical, as necessarily the eternal Torah and truth would be expressed in different formats, based on the situation that calls for whatever way it needs to manifest itself. For more on that idea, see Psychology of the Daf, Yevamos 35.  If so, only a prophet that can comprehend God’s timelessness can give a timeless Torah that has 49 ways to express permitted perspectives, and 49 ways to express forbidden perspectives. (For more on that idea, see Talmud Yerushalmi Sanhedrin 4:2 and Ritva Eiruvin 13b. “Coincidentally”, this is daf 49.)