How is the bitcoin price affecting other crypto currencies I am still pretty new to the crypto world, and especially to the world of finance.
When thinking about buying some alt coins I realized that this is in most cases only possible via Bitcoin. 

My questions:

Isn't the current price of Bitcoin and it's volatility directly influencing/affecting all alt coins that can only be bought via Bitcoin? 

How are the prices of alt coins calculated to not show this dependency? 

This is a very broad question I guess. Appreciate any help!
Agree that it's a broad question, but here is the specific answer to the parts you mentioned directly: yes, the price of bitcoin does directly affect the price of altcoins, and there is usually no calculation to avoid this, as the price of altcoins on exchanges are usually given as prices in bitcoin. Then to convert to USD, the current bitcoin/USD rate is used. Keep in mind that you can always use the bitcoin/altcoin exchange rate instead of the calculated USD/altcoin rate because that isnt affected by the bitcoin/USD rate directly (although it is, because the markets are related in other ways too, such as investor confidence in cryptocurrencies in general)