Delderby Loc: Derby UK

Yes - that crystalises the subject nicely - thinking on a bit, to promote a feeling of isolation, necessarily surrounding the subject with space, empty or otherwise, conflicts with the old rule of filling the frame, unless we accept that the empty space is actually part of the subject.

PoppieJ Loc: North Georgia

if you mat your photos when you frame them then you can crop however you want. there is no rule that I know about that says a mat has to be the same size all four sides. One thing that I do is crop the picture how I want it to look, plan for a mat, then size picture and mat for the frame. The picture may end up smaller or bigger that I really wanted but it is the crop that I wanted and I get to present the picture my way.

Delderby Loc: Derby UK

Yes - there is no rule to say that the mat has to be the same size all round. However, I think the widest side of the mat needs to be at the bottom, followed by the top .This still means that most crops can be accommodated.
Most of my prints are 4/3 (or3/4) with a few squares, and my frames are mostly A4 with a few squares. My "mats" are usually a printed border. There is an app called XNview which has a really good adjustable printing plan for placing a picture anywhere within a paper size that I invariably use for borders (or no borders).
Happy shooting, Del.

btbg

You can always purchase metal frames in pieces so that you put them together yourself and can make virtually any dimensions you want and still buy in bulk.

Another option is to crop to best fit the image and then mat to fit the frame. There are lots of ways to approach displaying photos and one size does not necessarily fit all.

R.G. Loc: Scotland

Cropping to specific aspect ratios is going to be restrictive. Every image will have its own optimum crop, where "optimum" is determined not just by content but also by the intended look or feel that you want to achieve. The important thing is to be aware of all the options and their consequences.

If you crop close you may lose a feeling of space, openness, distance, isolation, remoteness, starkness (or whatever). You may also lose relevant context, which can negatively impact the storytelling and/or the general interest of the scene. Main subjects don't have to be the only source of visual, mental or emotional interest. Having said that, you don't want context to be too distracting and you don't want the context to excessively weaken the storytelling (a weak subject will be more susceptible than a strong one).

If you crop wide you may lose a feeling of intimacy, connection, closeness etc, plus you may lose visual emphasis on the subject/s (depending on the relative strength of the subject/s versus the strength of the distractions). You as the creator need to decide what is your intention and what is the desired look/feel. There is no absolute right or wrong such as "You should always crop to the subject" or "You should always eliminate anything that isn't directly related to the subject". It's very rare (but not impossible) for that approach to produce an optimum crop.

What's important is that the end product is the result of a considered acceptance or rejection of the various possibilities (which you need to be aware of). That applies to other aspects of an image, not just composition and framing.

Delderby Loc: Derby UK

One way to help the decision is to keep four strips of mat board to create a temporary frame for the picture, which can be readily adjusted for best effect. Once decision is made, it is only necessary to cut the inner edges of the mat to that size, and the outside edges of the mat cut to the frame you wish to use. It is rare that the frame alone will be of optimum dimensions.