Not long into the game, you can find a quest to locate a missing Telescope Lens for the telescope, which can be found by climbing the ladder to the left of the room where you awaken in Raven's Road Camp at the start of the game. But this lens cannot be acquired until you have found your sister, Adara, and filled the three Magic containers with volatile liquid.
The Telescope lens has to be purchased by a wandering merchant called Meldamus, located in Velhora Waterfalls, past Vigga Marshes.
Use the Bronze Crest to the west of where you found Adara to leave Vigga Marshes and return to a different area of Velhora Waterfall. Speak to Farven if you wish, just past the save point, or ignore him.
Above Farven's Fort, you'll see a seesaw. Place both characters on it, and then have one of them jump. This will alternate propelling the characters into the air. Up above is a ladder you need to grab hold of. Climb up, jump to the right, and use the crank wheel to lower the ladder.
When both characters are up, jump on the blue mushroom to get to the platform above, then go right. You'll encounter an Urlag, destroy it, jump on the blue mushroom in the thorns and continue till you see a seesaw and a spinning wheel.
Use the seesaw, propel someone up above, and use the crank to move the part of the ladder to the right. Quickly, climb up and onto the platform above, as the ladder will shift left to its original position.
Climb down the vines, avoiding the Urlag Scouts, and you'll be above the wheel. Jump onto the platform with the crank wheel, and rotate, so the platform moves down, so you can collect the other character.
Now head to the right, and you'll see water. Have Adara dive into the water, and float the platform over to Greak. Have Greak jump onto the water platform, and have Adara move it to the far right. Then this allows Greak to double jump over the thorns and speak to Meldamus, the wandering merchant who sells the Telescope Lens for 90 Cribes.
Buy it and return it to the telescope in Raven's Road Camp. You can now look through the telescope and admire the areas of Azur. It will also give you an achievement.
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