For half frame good enough, roughly near/mid/far and you are good. On 35mm this is not more tricky, but still doable.
The old folders until the 1950s used in most cases zone focus for medium format up to 6×9, I guess in this case you work just with f8 and smaller to get the focus right.

My plastic fantastic is the Nikon N80. Put the Voigtlander 40mm SL II on it and I get full matrix metering, manual controls (or auto exposure), beautiful images and pancake form factor. Or toss on any AF-D Nikkor for auto focus. Fuss free!

Like many I have seen truly moving images made by others in books and also many potential photographs as I go about my daily life.

But I have never clicked a shutter on a homeless person and I don’t think I ever would.

Why, I can’t really explain, although I think it’s a mixture of shyness and fear on my part with a respect for the dignity of others.

I also think it’s to do with a question of power.

Those with cameras – even the ubiquitous camera phones – ‘take’ or ‘make’ photographs and our subjects have little control over the final image.

We compose, shoot, crop and manipulate and delete to get the result we want. Even if our subject is understands all this and is in total agreement with the idea of being photographed they only see the result once we have made our creative decisions.

I am a hobbyist photographer and without the backing of a professional brief – for a charity or similar – to work to, I know if I did so it would almost certainly be a very furtive act – not just because I might alarm or anger the person I was photographing but also anyone who saw me.

In the same vein I would not photograph though at a funeral service.

And if ever did, what would I do with the resulting image or images? Who would I show them to? How would I explain what I had done and why, even to myself?

Photographing other human beings is an intimate act, one where those being photographed give away- willingly or otherwise – part of themselves.

Perhaps that’s why so many people hate their picture being taken and perhaps why many who dislike their own image being captured are photographers.

Often those who are homeless have already given or lost so much already.