いろんな言い方ができそうですが参考にどうぞ！
・Let's take a picture together!
一緒に写真撮ろう！
・Let's get a picture!
写真撮ろう！
・Let's take a selfie!
セルフィー撮ろう！
＜ボキャブラリー＞
take a picture = 写真を撮る
get a picture = 写真を撮る
take a selfie = セルフィーを撮る
let's ... = 〜しよう
Here the actual scenario and context is important. Who is this person? Have you met before? If, for example, it's a celebrity and you have an opportunity to take a photo, then,
"Would you mind if I took a picture with you?" is quite appropriate.
"Would you mind..?" is more polite than "Can/could I..?
If it's someone you already know - or a person dressed in Mickey Mouse costume, then just an informal, "Let's do a photo together!" is fine.
実際の脈絡が非常に大事です。この一緒に撮らないか、と言っている相手は誰なのか、一度会ったことがあるのか？例えば相手が有名人なら、
"Would you mind if I took a picture with you?というのが良いでしょう。
"Would you mind..?" は "Can/could I..?より丁寧な表現です。もし相手のことを既に知っている、またはミッキーマウスが相手なら"Let's do a photo together!" などカジュアルな表現で良いでしょう 。
相手と一緒に何かをやりたくて、誘いたいときは良くLet's という表現を使います。
なので、「一緒に写真を撮ろうよ！」と誘いたい場合、Let's take a picture togetherと言います。
他に、「一緒にランチ食べよう！」＝Let's have lunch togetherになります。
This is a polite way to ask someone.
By using the words 'please' or 'do you mind' you are showing them respect and using manners.
Phrasing it as a question means that you are not forcing them to do something, but asking them.
You are not assuming that they will do it for you.
It is a polite tone that you would use for them, so phrasing it as a question helps convey that tone.
これは丁寧な言い方です。
pleaseやdo not mindを使うことで、相手に敬意を示しています。
質問にすることで強制ではなく、尋ねています。
こうやって質問にすることで、お願いのトーンを表すのに役立ちます。
"Can we get a picture taken together." this means that you want a picture of both of you to be taken by someone else.
"Let's take a selfie picture together" means you are going to take the picture of by yourselves.
"Can we get a picture taken together."
一緒に写真撮りませんか？誰かにあなたたち2人の写真を撮ってもらう場合に使います。
"Let's take a selfie picture together"
一緒にセルフィー撮ろう。は自分たちで２人の写真を撮るとき。
To ask someone if you can take a picture with them, you can say:
"Can I take a picture with you?"
"Can we get a picture together?"
"Would you mind taking a picture with me?"
「一緒に写真を撮ってもらえますか」は、次のように言えます。
"Can I take a picture with you?"
"Can we get a picture together?"
"Would you mind taking a picture with me?"
（一緒に写真を撮ってもらえますか）
"picture of us" は「私たちの(一緒の)写真」となります。
「〜の記念に」は "in memory of 〜" と表現します。
例: Let's take a picture of us in memory of having traveled together! (一緒に旅行した記念に、写真撮ろう！)
他に "in remembrance of 〜" も同じ意味で使えますが、「思い出として」といったニュアンスが含まれます。
You would say "Could I please take a photo with you? " or "Would you mind if we took a picture together? " in a formal setting, with someone you don't know personally very well.
"Let's take a picture" can be used between friends or people you know well.
相手をよく知らない、フォーマルな場面では、
"Could I please take a photo with you?"（一緒に写真を撮ってもらえますか）
または
"Would you mind if we took a picture together?"（一緒に写真を撮ってもらえますか）
と言えます。
"Let's take a picture"（一緒に写真を撮ろう）は、友達など親しい人に対して使えます。
There are different ways you can ask someone to take a picture with you.
We should take a picture together. - This is more of a suggestion, that way if the person is not comfortable with taking a picture they can inform you.
Take a picture with me please. - A polite way of asking for a picture, rather than demanding, this way the person is a little more comfortable with taking a picture with you.
May we take a picture together? - This can be used if you're not that comfortable with the person, or don't know them well enough.
「一緒に写真を撮りましょう」はいろいろな言い方ができます。
We should take a picture together.（一緒に写真を撮りましょう）
これは提案に近いです。このように言うと、写真を撮るのが嫌な場合、相手は断りやすいです。
~~~~~~~~~
Take a picture with me please.（一緒に写真を撮ってください）
「一緒に写真を撮ってください」と丁寧にお願いしています。押しつけがましくない言い方です。
~~~~~~~~~
May we take a picture together?（一緒に写真を撮ってもらえますか）
これはあまり親しくない相手に使うことができます。
"Could we get a photo together?"
In this case, we've used the perfect conditional tense for "can", as we are making a polite request. Using "together" suggests that you would like to be in the photo with them. This phrasing is straightforward and simple.
"Would it be alright if I had a photo with you?"
As mentioned before, the use of the perfect conditional tense, using words such as "would" and "could", is a polite way of forming the question. By asking if it's "alright", you're ensuring that the individual is okay with taking a photo with you. The phrasing of this question would generally be more polite than the phrase above, as you are consciously asking if the individual is okay with having a photo with you.
"Could we get a photo together?"（一緒に写真を撮ってもらえますか）
ここでは、"can" の仮定法の "could" を使って丁寧にお願いしています。"together" を使うと、一緒に写真に写りたいことが伝わります。シンプルでストレートな言い方です。
"Would it be alright if I had a photo with you?"（一緒に写真を撮ってもらえますか）
上で述べたとおり、"would" や "could" などの仮定法を使うと、丁寧な質問になります。"alright" は「大丈夫である／問題ない」という意味です。これは「写真を撮ってもいいですか」と相手の意思を確認しています、上の例よりも丁寧な言い方です。
Do you mind if we have a photo taken together?' would be used when you want to be more polite, for example, with someone you don't know at all. If it's a young person or a mutual friend, you can use the more casual form of the question, simply, 'can I get a photo with you?'
Do you mind if we have a photo taken together?'（一緒に写真を撮ってもらえますか）は、丁寧な言い方です。全く面識がない人などに使えます。
相手が若い人や友達なら、よりカジュアルな 'Can I get a photo with you?'（一緒に写真を撮ってもらえますか）が使えます。
日本 
イギリス 
チリ 
ニュージーランド 
南アフリカ 
アメリカ合衆国 
オーストラリア 
