Learn English – modal verbs in conditional clauses

Instead of future real / unreal conditions let's put it this way

Future likely / unlikely conditions.

When the condition is likely you use the verb in the infinitive form

For example

1. If you try to take pictures of restricted exhibitions, a member of the staff will ask you to put your camera away. (Here you think that the person whom you are telling this is likely to take pictures in the exhibition)

Now suppose you are addressing the same sentence to a group of people (where they are unlikely to take pictures inside the exhibition) then you use verb in the past tense i.e.

2. If you tried to take pictures of restricted exhibitions, a member of the staff would ask you to put your camera away. (It means I don't think you will try to take pictures)

Let's see few more examples

1. If he asks me, I will tell him. (I think he will ask me)
2. If he asked me, I would tell him. (I don't think he will ask me)

So using the verb in its infinitive form or in the past tense causes the meaning of the sentence to differ a bit.

Let's see your last sentence and the thinking that goes inside when you use 'will' or 'would' in the condition.

As we know 'would' is the past tense of 'will'. So the verb used in the past tense denotes less possibility of something happening. So when you say

1. It would be great if you could learn something every time you went to a museum. (It means you don't think the person will try to learn everytime he visits the museum)

But when you say

2. It will be great if you can learn something every time you go to a museum. (It means you think that he might try to learn everytime he he visits the museum.)

Let's take TRomano's example

1. It will be great if you can stop by and say hello when you arrive on campus. (It means i think you will come)
2. It'd be great if you can stop by and say hello when you arrive on campus. (I don't think you'd come)