The resolution benefits of larger formats aren't as big as you might initially think for a number of closely interrelated reasons.
First, you always end up shooting at narrower apertures with larger formats (as the lenses have longer focal lengths for the same field of view, and hence less depth of field for the same field of view). In practice it's rare to shoot with a wider aperture than f/16 with 4x5. Diffraction therefore negates some of the potential resolution advantage of the larger sensor.
Second, large format lenses typically don't have the same resolution as lenses for smaller formats. This is partly because you can't have your optical cake and eat it (wider coverage comes at the price of lower resolution, all else being equal), and partly because the lenses are designed to be shot at small apertures anyway.
Third, owing to the typical focal lengths used, near-perfect focus will only be achievable in small areas of most 4x5 photos. You may get some of the resolution benefits you were hoping for, but only on that one tree that you focused on!
Fourth, you typically need long exposures with 4x5. Resolutions above ~20MP can't be achieved if the tiniest amount of camera shake or subject movement occurs.
In my experience (with cheap 4x5 equipment), I can usually capture slightly more detail than my 24MP D3300 with kit lens, if everything goes right. But then, anything you shoot with a 4x5 camera has to be standing pretty still, and stitching multiple shots to increase resolution is trivial with digital.
So I'd say that as awesome as a 4x5 negative is, the resolution advantages are marginal at best. It's absolutely not the case that you are getting 10x the resolution because the negative is 10x as long/wide.
This isn't in line what what others photographers (including myself) see.
Many respectable sources estimate 35mm to approach 24MP in the best conditions with specific film, 120 to be in the 40-80MP range, and 4x5 to be 100-300MP.
To address some of your other points: good LF glass can approach 70/70/50 line pairs per mm which is still really good, diffraction doesn't affect resolution as much as some people think, and f11-f16 is the sweet spot on a lot of modern LF glass - you don't need long exposures with those apertures and Portra 400, for example.
Honestly, the claim that 35mm film can achieve 24MP of resolution is pretty wild. That might be the theoretical resolving limit (depending on how exactly you translate lpm to megapixels, which is not so trivial), but no real world comparison that I've seen has ever shown 35mm film resolving as much details as a 24MP digital camera.
As far as what photographers like you are "seeing", then for goodness sake, if you are actually seeing 35mm film capture the same amount of detail as a 24MP DSLR, let's see the photos!
The f-number is a ratio, not a specific diameter. f/16 is not the same between a 4x5 lens and a 35mm lens of equivalent angle of view. A 90 mm lens at f/16 has an entrance pupil diameter of 5.65 mm, while a 28 mm lens at f/16 has an entrance pupil diameter of 1.75 mm.
So no, diffraction is not an inherent limiting factor of shooting 4x5 and you will in fact gain resolution. You will only lose depth of field (and your savings) when you go to larger formats.
Diffraction effects depend on the ratio, however, not the diameter. I didn't get through all of the forum post you linked to, but if it's saying otherwise, it's wrong.
The reason 4x5 appears to suffer less from diffraction for a given aperture is simply that the sensor is bigger, so that the blurring has relatively less effect.
Hmm, kind of the opposite here, I've never found anything supporting the contrary view!
Here's a quote from the forum discussion linked below:
> Yes, diffraction does depend on the absolute diameter of the aperture, at least that is what determines the angle of the diffracted rays. But with a longer focal length, the rays diverge farther before they hit the film, so the Airy disc (the fuzzy blob created by diffraction) becomes larger with longer lenses. When you get done crunching the numbers you find that the final result -- the physical manifestation of diffraction on the film -- is dependent only on the f/stop, and the focal length and absolute diameter of the aperture make no difference. A 20mm lens at f/22 will create the same size Airy disc as will a 200mm lens at f/22. In short, all lenses will produce the same amount of diffraction when set at the same f/stop.
So of this is correct, it's in a sense true that diffraction depends only on the absolute diameter, but the effect of diffraction on resolution is dependent only on the f stop.
If your 4x5s are barely beating your D3300, that's on you. Only the higher end medium format digital really matches 4x5 in terms of resolution. Now, if your argument is that you only print 16x20 so it doesn't matter, then that's fine, but that's a completely different argument.
The reasons to use large format, as I see it, are as follows:
* Lens choice. There's a wealth of options here that you simply don't get with smaller formats
* Movements. The mild DoF hit is easy to accept when you have complete control over the focal plane, as well as the distortion control
* Film. Digital PP still isn't quite up to replicating the chemistry. Someone good, and with a significant effort, can get really close, but it's not quite the same.
>If your 4x5s are barely beating your D3300, that's on you. Only the higher end medium format digital really matches 4x5 in terms of resolution
These two statements contradict each other. There is not much difference in resolution between 24MP and 50MP (4.9 : 7), so if I was getting ~50MP of resolution in my 4x5 negatives, you wouldn't expect to see a big difference, even if I was doing everything right.
>Moreover, if you do a 'DSLR' scan of the negative, you can get quite a bit more detail.
This is in fact what I do (using a very sharp pre-AI 55mm Micro Nikkor). I do get benefits from stitching multiple 24MP "scans", but this is because there is always some resolution loss in scanning. So, sure, I might end up with a 100MP file, but I find that I can typically reduce that down to around 30-40MP without losing any detail.
Do you have an example of a 100MP scan of a 4x5 negative that loses detail when reduced to, say, 50MP?
First, you always end up shooting at narrower apertures with larger formats (as the lenses have longer focal lengths for the same field of view, and hence less depth of field for the same field of view). In practice it's rare to shoot with a wider aperture than f/16 with 4x5. Diffraction therefore negates some of the potential resolution advantage of the larger sensor.
Second, large format lenses typically don't have the same resolution as lenses for smaller formats. This is partly because you can't have your optical cake and eat it (wider coverage comes at the price of lower resolution, all else being equal), and partly because the lenses are designed to be shot at small apertures anyway.
Third, owing to the typical focal lengths used, near-perfect focus will only be achievable in small areas of most 4x5 photos. You may get some of the resolution benefits you were hoping for, but only on that one tree that you focused on!
Fourth, you typically need long exposures with 4x5. Resolutions above ~20MP can't be achieved if the tiniest amount of camera shake or subject movement occurs.
In my experience (with cheap 4x5 equipment), I can usually capture slightly more detail than my 24MP D3300 with kit lens, if everything goes right. But then, anything you shoot with a 4x5 camera has to be standing pretty still, and stitching multiple shots to increase resolution is trivial with digital.
So I'd say that as awesome as a 4x5 negative is, the resolution advantages are marginal at best. It's absolutely not the case that you are getting 10x the resolution because the negative is 10x as long/wide.