[Zig]

Firstly, about the images above: there is only one exposure: the second one. The first image is a crop.
There are several reasons why we wish crop an image; likewise, there are several factors that affect whether this is effective or not.
Have a look at the first one above: this is the smallest crop I have done from the base image. You can see that though this crop was taken from the centre to the edge-ish, there are already 3 "justifications" to crop: there is no significant degradation or softening towards the right of the frame as we move towards the edge of the initial exposure; the amount of detail and integrity of the "drawing" suggests a crop could hold up pretty nicely...and there is enough compositional interst to make it worthwhile.
All of which sound obvious, yet the amount of times we are forced into or away from a cropping choice is worth noting: If I'd still had my 16-35mm f2.8 MkII, I wouldn't have had the luxury of choice, as the amount of softening away from the centre by 21mm would either have preventing me from framing the shot the way I have, or would have forced me into shooting specifically so I could safely crop away the outside 30%. There is little or no point having, say, a sensor capable of blatting away at 21MP, if a third of what you take is wasted..that is, you won't resolve 21MP-worth pro rata in the edges or corners. Conversely, one might then say at least the extra pixellage allows one to waste off the outer bits and still get a highly-enlargable and detailed print!..Yet, bloating megapixels because of an admission that we produce lenses that are naff in Zones b and c, is hardly a stellar seller.

I really had a problem taking this shot: the problem was, was that I could see several compostions that not only worked but were individually very strong.
In short, my logical solution to this dilemma was as follows:
I knew it would rattle and unsettle the subject if I unslung my pack, rummaged around for another lens and re-framed so as to get the 3 or 4 compositions I wanted...er, and guess who didn't have his 50mm on him? :o I could see that as my only alternative was to strap on the 70-200, I had to make do. Besides, the tele would add to the intrusion and I didn't want a volatile Italian lady ruffled when I had my back already to the wall quite literally. Plus, I had a 21mm class prime: I was aware of its resolving power, its performance across the frame and so I made sure I had the lens at its optimum and sharpest aperture: f5.6.
I was also helped by knowing the amount of depth of field I'd have at that aperture and that distance.
This might seem obvious again, but having a distance scale and knowing how to use it does help; similarly, getting to know in advance how the edges and corners of your lens look across your apertures, is way of being prepared and adding to both confidence and keeper-rate. Sorry to sound evangelistic, as I've no wish to be..it's just that I've found doing this has helped me at any rate.
The final asset of a wide prime is the depth of field...practically, I find this to mean how ACE and necessary manual focus is, and a well-weighted response when one turns the focussing ring...you can prefocus the lens, leave it and proceed in the knowledge that when you take the pic it will be in focus. In fact, autofocus here is time-consuming and impractical..and unnecessary. As an aside then, if any of you were considering adding a wide prime to your armoury...I'd suggest getting a manual focus one, honest!

OK, given that I was confident that I could not just "get away with" cropping, I could work towards getting at least 3 class keepers. This also allowed me to make the following adjustments: I would maximise my chances by eliminating as far as I could, converging or diverging vertical lines. Now, if I did that, I'd have to include a wide expanse of foreground. Mercifully I found that I could choose a composition that would both allow this yet be a decent image in its own right.
And it was at that point I took the shot..that is, the second image above.

I knew that this full-frame shot would "work": it might not be the strongest of all the compositions I had already seen within the frame, but this time I felt the full-farme image would be my "bonus shot"!
In summary, I guess: this shows once again my modus operandi: I'd already planned not only one final image but several within the image, in advance: and this way I wasn't merely cropping afterwards in the post-processing stage and experimenting to see if it works or not..I already had a good idea of at least 3 planned images. And if they were planned..that is, if I had more control over these images rather than allowing them to be also-rans from some random post hoc experiment, well, I thought, they'd be all the better for it.
Now, I'm usually a one-take sort of chap..and I like to go full-uncropped with the Zeiss just because I can and the Zeiss can...so this image(or, these images) was rather a handful for me to think about along with taking the shot and working out how many flavours on my ice-cream I could have
Again, I post these for no other reason than thinking some bits might be useful, so don't bother telling me which ones don't work

Here, then, are all the shots from that initial exposure. Notice of course that I've pp'd diferently depending on whether I've felt the crop suggests a different mood...and that leaves us with that most interesting of points: that cropping a shot and pp'ing it can greatly vary the message and emotional impact on one's viewers. It was because of the manipulative nature inherent to cropping that several in the Cartier-Bresson school decided to always go full-frame-uncropped...a safe bet they used Leica Ms then: not much edge softening there(eh, Toad?!) Hmm...interesting thought: when is cropping used as rescuing, when is it used to tell a lie...?

[Toad]

Great discussion of your workflow. I know that you don't want to know but anyway, I like the last crop.

Cropping is of great interest to me. I am a brutal cropper in my own stuff, and I will always crop to get to what I think is the "essential" part of a photo even when that essential part is only a very small bit of a much larger photo (thats where I disagree with Cartier Bresson). I am not too concerned with corner sharpness because I crop everything.

So what about all the lost pixels when you crop? I don't have an answer for that, Some of my crops are stupidly small pixel wise - but say what I want to say.

Anyway - great post!

[Wedding Shooter]

Nice work Zig - I crop a lot of my wedding work. I think creative cropping makes pictures stand apart. Sometimes my crops are simply because I could not get closer and did not have time to change a lens.

[Zig]

Yes chaps, I certainly also adhere to the practice for the reasons you mention.

I've had a brief review of my Alexandrine library of archived shots, noting that generally the wider my lens, the less I crop...maybe because I like the immense "walkability" of having a landscape in vertical fullframe.
I forgot to mention the times when cropping or composition is constrained by the aspect ratio or print size of the final product: the amount of times I've wanted an A3, only to find it won't "go"! My workaround then is perhaps to get the image at the aspect ratio it works at, then add an arty border/sig to pad it out to the required output size. Any of you like get into a muddle with this?

[Wedding Shooter]

Can happen when people want an 8x10 and there is not enough space on either side. I usually try to allow for this with family photos.

[nia]

WOW! This is great, dear Zig, I can't choose, they are all amazing... Thank you for this thread, this is such a beautiful to learn more about photography, fascinated me.

with my love,
nia