Simple Way to Crop to a Focal Length in Editing

[wibbly]

I'm interested to know if there's a simple way to crop a RAW file to a specific focal length in LR or PS.

Example... I have an image shot on a full frame 35mm focal length lens and would like to crop it to a specific 90mm focal length.

I'm not interested in compression etc. simply how a composition would look at 90mm rather than 35mm.

I've Googled it, but it appears there's no simple option to allow this...

Anyone know of one?

 

[MDH6D]

The simplest method that I can think of is to use the relative field of view angles.

The horizontal FOV for 35mm is 54.4 degrees and the 90mm is 22.6 so there needs to be 0.415 times the number of horizontal pixels to simulate a 90mm lens.
The vertical FOV for 35mm is 37.8 degrees and the 90mm is 15.2 so there needs to be 0.402 times the number of vertical pixels to simulate a 90mm lens.

You can just plug the resultant numbers into the PS image size menu and Bob’s your uncle.

This is probably not as simple as you would think it should be but I don’t know of an easier way (It’s probably not a commonly required operation).

 

[wibbly]

The simplest method that I can think of is to use the relative field of view angles.

The horizontal FOV for 35mm is 54.4 degrees and the 90mm is 22.6 so there needs to be 0.415 times the number of horizontal pixels to simulate a 90mm lens.
The vertical FOV for 35mm is 37.8 degrees and the 90mm is 15.2 so there needs to be 0.402 times the number of vertical pixels to simulate a 90mm lens.

You can just plug the resultant numbers into the PS image size menu and Bob’s your uncle.

This is probably not as simple as you would think it should be but I don’t know of an easier way (It’s probably not a commonly required operation).

Thanks! Appreciate your response. I’ll give it a try in PS.