Why is いつも used in this sentence?

Question

Consider this sentence:

いつもと変えてたまに外で食事しよう。

This was translated as:

"Let's occasionally change where we go to eat out."

I have two questions:

1. If いつも means always/usually, I don't understand how that fits into the translation because たまに expresses "occasionally".
2. If いつも is an adverb/noun, how is the と particle used in this sentence?

An explanation of how the grammar works would be appreciated.

Answer 1

「いつもと変{か}えてたまに外{そと}で食事{しょくじ}しよう。」

And someone translated that to:

"Let's occasionally change where we go to eat out."

Now, I have to say that the original and the translation do not match at all. Frankly, the translator does not seem to be very proficient in Japanese.

The speaker of the original sentence (and his/her group/family) usually eat at home. (いつも = usually) On this particular day, however, s/he is suggesting to make a change in that habit and go out to eat instead. Are you following?

The problem is that that is not what the translated English sentence says at all.

1. If いつも means always/usually, I don't understand how that fits into the translation because たまに expresses "occasionally".

As I stated, that translation is a complete flop. It would not be very productive to discuss which word went where.

2. If いつも is an adverb/noun, how is the と particle used in this sentence?

Here, 「いつも」 is a noun, so no problem with the 「と」. This 「と」 indicates the "standard" when talking about making a change. 「いつも」 is the standard and they want a change from that and go eat out.

Answer 2

First of all, when I read that sentence I think it means something more like:

Instead of always [eating here], let's go out to eat once in a while.

or perhaps,

Changing from usual, let's eat elsewhere occasionally.

いつも here is kind of being used as a nominal, yes, but really the nominal you are dealing with is in fact いつ itself, followed by two particles (も and と）. と is being used in its coordinating sense, the same way it is used in これと違います ("it's different from this").

You can think of いつも as what is being changed by 変える. と can link a nominal to a predicate (see chapter 10B-3 of Japanese: The Spoken Language) carrying a sense of "accompaniment." This meaning is so broad that it allows us to construct sentences like　いつもと変える ("different/changing from usual") and 課長と相談する ("consult with the section leader").