I sold my LF camera years ago, but funnily enough, I just had a sheet of 4x5" (admittedly using the very sharp and grain-free Acros 100) that was drum scanned to 350mb yesterday, and was having a good look at it last night.
At 50x40" at 300dpi, grain is almost invisible (even with a lot of sharpening), and I was surprised at just how much more real detail is in that 4x5" file ..... compared to a 38mp camera I've played with recently (a Leica S) at that sort of 50" wide print.
I think if I turned a 38mp Leica S vertically on its side, however, and rotationally stitched 2 or 3 images together to produce a 50"x40" print, it would probably all look a lot closer to the 4x5" drum-scan -- at that stage, the "long side" of the 38mp sensor is being asked to achieve 40" in print terms, which isn't a stretch.
I hope this isn't veering off track, but what do you see as benefits from rotational / nodal stitching (eg, using a DSLR), versus in-camera stitching (eg, using a tech cam like an Alpa STC)? Note, I have NOT bought a nodal plate yet, but am trying to simulate a nodal stitch as best I can handholding the camera, and every time the 3 files are merged, it create a shape like a "Bow Tie" ..... eg, I have to cut off the top and bottom of the Bow Tie on both sides of the aggregate file. Is that what I should expect to occur with nodal stitching, EVEN when I eventually get everything perfectly aligned using a nodal slide??
And in comparison, what does one get with something like an Alpa STC for 3-stitch effort (middle shot, then left- and right-stitch?) - presumably everything is perfectly lined up, with no bow-tie effect?
The film-vs-digital resolution comparison is very coarse and depends on many factors, film type a major aspect of course. Personally I think film have an advantage of looking good even if over-sized. No-one likes seeing pixels when nosing a print, grain has a more pleasing appearance, and indeed it's quite common to add grain simulation on digital prints to have them look more pleasing in huge format. Film also resolves monochrome detail way past the grain which gives it a special quality. Saying that 4x5" is about 40 MP digital is if you want to feel good about digital, but if you dig past the grain into the true max resolving power you get up to 380 megapixels out of a 4x5", again using Tim's test as a source:
https://www.onlandscape.co.uk/2011/12/big-camera-comparison/ , but that is a bit theoretical.
Anyway on to the stitching question.
The bow-tie effect is normal, and that is because you convert your stitch into a rectilinear projection. If you have shot an ultrawide lens sometime you have probably noticed the stretched perspective along the sides of the frame. When you stitch with a longer lens and want to make the same field of view as a shorter rectilinear lens you need to make the same stretch, hence the bow-tie effect. If you make say a cylindrical projection instead (which can work well for landscape panoramas) you don't need to cut away as much. In any case getting a nodal plate won't change anything of that.
When you stitch inside an image circle the sensor is already seeing a rectilinear projection so there is no projection remapping required, and this is how you typically stitch on tech cams.
An advantage of nodal point stitching is that you always use the sharpest part of the lens, the center, even to render the "corners" of the final image, and of course you don't have any limit on how wide angle view you want, just shoot more frames. Nodal point stitching can replace both shifting and wide angles, but it means more computer work and thus a less effective workflow. I have only used Hugin as stitching software (highly competent software, but not user friendly), but there should be better alternatives, still I hear often than people have trouble in recreating the proper perspectives (which they succeed with when using shift on a tech cam). In theory it should not be any issue, so I think it's related to software. Anyway, the point is that with nodal point stitching there seems to be more of a challenge to get the end result you want, but if you do get deep into it it's possible.
With my DSLR I have a nodal point stitch head and I made some stitches. You can get a huge amount of megapixel in any projection you want. However time-consuming and I did not find it a very pleasing way to make images, just too mechanical and the reprojection made the composition a bit unpredictable. With the tech cam the workflow is typically a little bit more efficient, less overlaps, less shots and you don't need to reproject the images so the composition is more predictable. Still I personally don't stitch even on my Linhof as I'm a fan of the one shot image shooting experience, I rather use a wider angle and sacrifice some resolution than stitch, but that's me.
Here's an example from my DSLR days when I made a cylindrical stitch for a huge panorama (disclaimer: this image is so much
not my style these days
). These type of perspectives does not hurt from cylindrical projection, I'd say they even gain from it as you don't get stretch effects which can be a bit ugly at times. When shooting architecture or other stuff which straight lines in it you need to use rectilinear projection though. I *think* there's software today where you can mix cylindrical and rectilinear in the same image, for example if you have an extremely wide panorama with a bunch of smaller buildings in it, you can make sure that each building has straight lines but the overall panorama is cylindrically projected. Again, lots of post-processing work in that case.
And here's an example of that bowtie effect, before cropping down. To make the lines render straight a rectilinear projection is required and then stretching on the sides is necessary:
And finally the exact same image material projected cylindrically, before cropping. As you can see you will loose much less, but you get that "fish eye effect". However you only get bends in the horizontal direction, vertical lines are rendered straight (eg tree trunks), this is what makes cylindrical projection often work well for landscape panoramas.
