Mastering perspective: Exercise 07  I'm having trouble

Hi! I was just going through some exercises from the Mastering Perspective exercises PDF but I got stuck on exercise no. 07: Spacing. It says to add 5 more posts in a drawing, where the first and last post have already been drawn in a one point perspective. I understand how to figure out where the third (and forth, and so on) post would come if you would just guess where the second posts is placed. But now you've got the last post already placed and I'm confused!
I tried dividing the space into halve and placing the third pole in the middle. And then divide the new halves into halves again and those into halves again to find out where the other four posts should be placed. But that doesn't really seem to work. I'm alright when it comes to guessing or estimating these things, but when something looks a bit off and I want to check I just can't figure it out. There being 5 posts to be added instead of 4 makes it a whole lot more complicated it seems.Does anyone know how to handle this assignment? (Apart from just winging it. Because I know how to do that :D )

Hello Taru!
Always using rulers and guides, trace a line between the top of the first post (let's call it post A) to the bottom of the second one (far in the distance, let's call it, post E). Now do another line between the bottom of post A and the top of post E. Now you'll have an "X" between those two.
The next step would be to connect the top of A with the top of E and the bottom of A with the bottom of E (creating perspective lines). You'll end up with a skewed box with an X in it. This is sorted out in the workbook. Now draw a new post going throug the center of the X, where the lines we first traced meet. Use the bottom and top lines of the "square" to start and finish the post, so it will be in perspective. This will be post C. It should look like it is in the middle.
Now we need to trace a post between post A and C, and another one between C and E.
We just need to repeat what we just did. Trace a new "X" between these, going from the top of post A to the bottom of post C. Then again from the bottom of post A to the top of post C. Now that you have another "X", draw post B where those two lines meet.For post D, just repeat the process of creating an "X" between post C and post E. You could keep doing this indefinetly! At this point the "box" should be dividided in four smaller boxes, and you should have 5 posts. Erase the guides and keep just the post. They will be all in perspective!
I hope I made it clear and this can be of help. Best of luck!

Oh, I see you need to add another two posts to the equation! Let's think about post F then!
Let's say we want that post to be farther back, beyond post E.
What we'll do is find the middle section of the posts, horizontally. For this, we will trace a guide going through all the "X" we traced before (before we did this vertically, to draw the posts, we now do this horizontally, to follow the perspective and figure out the middle of our posts). Now we should know where the middle of our post E is.
The next thing is to make sure our perspective guides are going farther back, into the vanishing point. So we use a ruler to expand them (we already traced them before, going from top of post A to top of post E, and bottom of each, too). This is sorted out in the workbook.
What we'll do next is trace a line from the top of post D and through the middle of post E. But we wont stop there. We will carry on with that line until it touches our perspective guide from the bottom. That would be were the base of post F is located.
Now to find out where the top of post F is located, we trace a line from the bottom of post D, through the middle of post E and finishing when it touches the top perspective line.
Now we should have the top and bottom of post F figured out. We just need to connect those two with a vertical line!
We repeat the process with post G!
And in the end, we shuold have 5 new posts evenly paced and in perspective!
Was this clear? I hope it was of help! Let me know if I can make something clear!

I think perspective is kind of amazing how you can use all these lines to figure things out! Not my strong point yet but I have always been amazed by it :) I like the explanation you gave, @BorisBayo. Especially the part that explains how to keep going beyond the last pole. I have a book I really like to refer to called Perspective Made easy that explains things very well too. @Taru , have you seen it? You might like to check it out. They probably have it at the library. Here's a link to it on Amazon.

@borisbayo Thanks for the clear explanation! Drawing the crosses really is a great way to place things in perspective. However, it seems a bit like cheating by adding the post after the last predrawn pole though :P What if you want to place all five of them in between the two predrawn poles?
@MarshaKayOttumOwen Thanks for the tip! I came across it in the SVS Mastering Perspective video's and I've added it to my wishlist for books to buy :)

These are from the book
, just for another explanation