RESOLUTION COMPARISON: VIEW CAMERA vs. DIGITAL SLR

Introduction

I took the same picture with two cameras:

the Bender 4x5, loaded with Fuji Velvia 50 and a Caltar-S II f5.6 150mm lens, and
the Olympus E-1 with the ZD 14-54mm f2.8-3.5 lens.

The pictures were taken from Belvedere in Macugnaga, Italy, in mid August 2006. They show the glaciers and mountains to the east of the town, the tallest of which, Mount Dufour, is 4638m high (about 15,217 feet).
In order to get to Belvedere, you have to take two chairlifts from Macugnaga, or a couple of hours walk on foot - not recommended if you are carrying a view camera :)

Links

	This is a low-resolution scan of the 4x5 slide. I marked with red rectangles the areas that I enlarged and cropped for the comparison. The first from the left shows a detail of the glacier and the surrounding rocks. The second shows a few branches with the backdrop of the mountains. The third shows another detail of the glacier.
Note: I know this is not a great picture and doesn't deserve all the resolution it has... but it's the first picture I took with a view camera and I was itching to use it.

Comparison Details

I took the pictures in the late morning, just a few minutes away from each other. The clouds were moving very quickly, so I tried to compare points that were in good light in both pictures.
I didn't take the pictures with the two cameras from exactly the same spot, so the closer objects (such as the trees) appear in a different perspective in relation to the farther objects. This is apparent in the second detail, but it doesn't really matter for this resolution comparison.
I took the E-1 picture with a slightly longer focal length, so I had to adjust it a little to make a fair comparison. The 5MP of the image were concentrated in a field of view that was narrower than that of the view camera, so I calculated how many pixels I would have had in that same region had I taken the picture with a wider focal length, and resized the image to that number of pixels.
The 4x5 slide was processed and then drum-scanned; due to the high cost of scanning and the fact that I don't intend to print this picture in a large size, I decided to scan only a portion of the picture itself; the scan produced a 100MB file; the same resolution applied to the entire picture would have yielded a 300MB image; in other words, I obtained a 38.5 megapixel crop of a picture that would have been 105 megapixels.
I used Photoshop's bicubic interpolation function to enlarge the E-1 image to exactly the same pixel size as the film scan. Then I cropped the matching comparison areas from both pictures at 100% magnification.
Here they are:

Bender 4x5 View Camera (105MP scan)

Olympus E-1 dSLR (5MP)

Conclusions

There isn't much to say; the resolution of the 4x5 clearly blows away that of the digital SLR.
I could have scanned the slide at even higher resolution (it's technically possible to obtain a 500 megapixel picture from a 4x5 scan), but I doubt that the result would have been significantly better. The scan resolution is obviously not the only limiting factor in the detail that you can get out of a film slide.
On the other hand, I could have used a 10 or 12MP dSLR and that would have certainly given a boost to digital; still, I think the advantage of large format will remain great at least until (if ever) we start seeing 30MP+ digital cameras.
One important point to remember is that digital cameras claim a number of pixels that is not quite right: when I scan a slide, I get full color information from every pixel; digital cameras, on the other hand, get only one primary color from each pixel and "guess" the other two. So when a digital camera claims to have 12MP, a lot of that data (two thirds of it) was never really captured, it was just made up by the camera.

To put things in perspective, many people report that the E-1's resolution is sufficient for acceptable prints up to 16x20 (about 41x51cm). This means that the extra resolution provided by a 4x5 camera is useful only for extremely large prints. In everyday situation, the 4x5 drum scan is overkill.

Of course I should also point out that resolution is not the only factor in deciding which camera is better or better suited to a task. Getting to Belvedere with the view camera, setting it up to take the picture, checking the focus and determining the correct exposure were a major undertaking; you can do the same things with the E-1 with barely a second thought, even in bad weather (thanks to its weather sealing). The camera that takes better pictures, ultimately, is not the one that you can't take with you.
Another non-trivial factor is the cost: with a view camera you have to buy film, send it for processing, have it scanned and sent back, for a total cost of over $150 (for a 105MP image). On the other hand, each dSLR shot is completely and wonderfully free.