Photoshop cropping technique (1/1 crop inside a 4/5 ratio)

[Marcoz]

Hello guys , I’m trying to do one thing in photoshop but couldn’t came up with a solution so far,so I hope you can help me out with it.
As probably many of you knows on Instagram photos are shown as a 4/5 ratio but on the feed pics are actually shown as small squares.
This is pretty complicated to explain but I’ll try .
Is it possible to crop in photoshop with a 4/5 ratio and see in the meanwhile how is it gona look on a 1/1 ratio?
I mean I would like to be able to crop a 4/5 pic and move it up or down inside that 4/5 frame and have in the meanwhile a steady square which will show me how much of that pic will be shown on my feed.
I tried with the rulers but the problem is that the ruler move with the pic if I move it up or down and I need it to be steady right in the middle.
So far I’m cropping on a 4/5 and then I recrop momentarily to a 1/1 to check that out and then back to 4/5 but it’s quite annoying to do that each time .
what am I missing?
Thanks everybody

 

[Eggy]

Open your image.
Duplicate it (ctrl+J) and click away the eyeball of the original layer. (I never work with the original)

Activate the crop tool and in the 'selection' dropdown box choose ratio 1:1.
Do NOT crop!
You can reduce the size of the crop by holding shift+alt (to constrain the proportions) and go to a corner of the crop and reduce the size.

While the crop tool is still active pull vertical and horizontal guidelines to the edges of the crop (they will snap in place)
Select 'don't crop' in the crop box. The crop bounderies will disappear.

Use the rectangular marquee tool to draw a rectangle on the guidelines (they should snap into place).
This is your 1:1 selection.

Now you have your picture, your guidelines and your selection in 1:1 (marching ants).

To move the selection around press and hold the M key and drag the selection to where you want it with your move tool.

When/if you're happy with the placing of the selection press ctrl+J and that part will be a new layer in 1:1 ratio.

 

[Marcoz]

Wow thanks very much !! Great answer.
I think I’ll actually stop the process with placing those guidelines on top and bottom , that’d be enough to see The square in within the frame.
For curiosity when I used the marquee tool to build that square and then hold the m while moving it moves the marquee square around but not the pic itself and if I simply use the move tool it cut the image inside the square and only move that around ..am I missing anything?
Anyway as I said those guidelines will do me well!
Thanks again

 

[Eggy]

Did you press and hold the m hey and used the move tool?