I have been learning for a few years.
How extensive is the vocabulary in a sign language compared to a spoken language?
Signed languages are like any other language in that they have an extensive vocabulary and grammar system. There isn't an ASL sign for every english word, just like there isn't a french word for every english word. ASL is very different from english and other signed languages in english speaking countries like BSL or AUSLAN. ASL has a lot of signs that do not have english equivalents. However, just like any language, ASL borrows words from english. We see english also borrowing words from other languages (pasta, RSVP, etc). This is called loan words and all languages do this. ASL does this in the form of fingerspelling and lexicalized fingerspelling. ASL is a relatively new language compared to English, so it is still developing and evolving. There are still many English words and concepts that do not have specific signs yet, especially for more specialized fields like words in medicine or legal jargon. However, signed languages are unique in that they are visual languages, and even if there isn't a specific sign for a concept, you can try to show or explain the concept using a series of other signs or gestures. So there might not be a single sign to represent a specific word in English, but you would have to break down the english word into what it means, and sign that instead. There are communities and dictionaries being developed by Deaf people in specialized fields to come up with more standardized vocabulary for STEM discourse in ASL so they can rely less on fingerspelling (see aslcore.org and aslclear.org)
Are there signs that you find hard?
Sometimes lexicalized fingerspelling can be the hardest signs for me to learn. For example the sign #STYLE is spelled while moving your hand quickly in a circle. lexical signs are signs borrowed from english using english letters, but morphed into a sign. It often involves dropping some letters and having some kind of movement associated with it (see ASL signs for #DOG, #BANK, #BACK, #DO, #NO, #PIZZA etc). MOst signs aren't difficult to learn though.
Do you often encounter signs that you don’t know?
Yes, as a student, I am always continuing to learn new signs. There are many different regional signs, so I may know how to sign something, but then when I talk to someone else, they use a different sign. There are so many different variations for signs. the word Halloween, I have seen over 10 versions for. Pineapple has at least 5 variations I have seen, and strawberry has over 20 ways to sign it, depending on where you live.
Do you often experience that you use different signs than other people that use the same sign language?
YES! see above
How much would you say your sign language depends on mouth movement and body language?
I've heard it said that 50% of the language is in your hands and the other 50% is facial expressions, mouth morphemes and body movement. These are a HUGE part of the language, and the face you make while signing can actually completely change the meaning. For example the sentences "do you understand", "I understand" and "I don't understand" are all signed exactly the same way but with different facial expressions and head movements. You can also use mouth morphemes to emphasize something. You wouldn't sign very bid, just big and your mouth shape would show how big you mean.
Was it hard for you to learn sign language? / Was it hard for you to learn a spoken language?
I only know English as a spoken language. It was much easier for me to learn ASL than trying to learn other spoken languages. I picked it up much faster. (I am more of a visual learner). ASL isn't an easy language, I just prefer it to trying to figure out how to pronounce words in other languages. So for me ASL is much easier to pick up because it is so visual. But many people struggle with learning ASL.
What are, according to you, the major differences between spoken languages and sign languages?
Do you use sayings in sign language, if so, are they the same as in spoken language, or are they specific to sign language?
Yes there is specific slang and idioms in ASL. ASL has its own words that don't have an English equivalent like "pow", "pah," "kissfist", "VEE-VEE", and it also has its own idioms like "train gone", "finish-touch", "think-disappear". English idioms don't translate well in ASL, you would have to sign what it means, not the english word for word because it wouldn't make sense. For example "raining cats and dogs" you would just sign rain, and use your face and body to show that it is raining really hard. There aren't literal cats and dogs falling out of the sky so that would look ridiculous in ASL.
What’s your favourite part about deaf culture?
I love the people, the Deaf community. They are typically very friendly, though often blunt. I love getting to make new friends through shared use of a language.
Have you ever tried to communicate with another signing person that doesn’t know the same sign language? If so, what sign language and how did it go?
When I was still just beginning to learn ASL, I studied abroad in Australia. I saw a group of people signing and I went up to them to introduce myself. It turns out they were signing in AUSLAN, but one lady knew ASL as well, so she communicated with me and translated to the rest of the group. It was a cool experience. I have also communicated with someone online who is learning ASL but fluent in BSL. They taught me the BSL alphabet. They were signing to me in ASL but sometimes used a sign I didn't recognize, because they were using some BSL signs when trying to sign ASL. I haven't yet tried to sign with someone who only knows a different signed language.