Converting a photo image for perspective

Not sure this is the correct area for this question.

Is there a way to take an image taken with 24mm in LR and crop it so I see the result had it been taken with a 50mm or 85mm? I am trying to gauge what I would lose in photo content using an existing photo.

Thanks in advance.

No. You cant crop for perspective. You can crop for field of view, but thats a different thing altogether. Perspective also takes into account the effect of the elements within the field of view, for instance the apparent difference in distance between a near subject and a far one in a wide angle lens like a 24 is enhanced. The same framing with a longer lens will flatten that apparent distance. Its not really a function of the lens but the working distance.

Thanks Gonzogolf.

Perspective in images is generally defined as the relative sizes of objects which are at different distances from the eye or camera.

To take what Gonzogolf said a bit further, please read our "sticky" (found in the General Photography Talk forum) tutorial titled Perspective Control in Images - Focal Length or Distance?.

mak65 wrote in post #16031375
Not sure this is the correct area for this question.

Is there a way to take an image taken with 24mm in LR and crop it so I see the result had it been taken with a 50mm or 85mm? I am trying to gauge what I would lose in photo content using an existing photo.

Thanks in advance.

To answer this a bit more specifically, yes, you can crop the image to match the field of view of a 50mm or 85mm etc. It will simply need the math to work out exactly how much to crop away. Hopefully one of the math gurus will know the formula to work out how much to crop and give you an exact answer.

As has been mentioned, the perspective will remain the same as you haven't moved, you will simply see less of the scene, but that is what you want to gauge the difference between the lenses.

In the field, you will see a perspective change between the different focal lengths, if you change position to fill the frame the same way with your subject. Your subject will remain the same size in the frame but other objects will appear to have changed size and distant ones will be noticeably larger in the frame with longer lenses.

It's about half from a 24mm (84.1° field of view) to a 50mm (46.8° FOV). Here's a wiki link for angle of view..

I think you just need to work out the percentages, and that'll tell you how much to remove.