14. June 2002
Medium format vs. 35mm vs. Digital

As an amateur photographer I'm sometimes asked why I bother using medium format, since the cameras are more expensive, the film is more expensive not to mention the hardware needed for scanning medium format slides.
I'm also sometimes asked how the quality of a (my) digital consumer camera output compares to scanning 35mm slides.

This article will compare medium format scans to 35mm scans and also to 3.3mp digital camera files.

[Update 17.06.2003] Don't miss the second article comparing the Canon 1Ds high-end D-SLR with scanned medium format film.
[Update 11.06.2003] Don't miss my new article comparing the Canon 1Ds high-end D-SLR with scanned 35mm film.

Making these comparisons are by no means my own idea - comparing different film sizes with digital camera output is in done many places around the web and is discussed in even more places.
This article is simply my contribution to this ongoing discussion.
I will urge you to follow some of the links from the links section below to see more articles about this subject.

How medium format compares to one of the current high-end digital SLR's is perhaps one of the most interesting issues at the moment. Since I'm an amateur working only with a consumer grade digital camera, my article here will actually perhaps more be a guide in answering the question: "What digital image quality will I get from a consumer grade digital camera compared to scanning slides from a 35mm (SLR) camera" - a question I believe many amateurs is asking in this years (well at least I did!).
I'd rather not discus all the other differences between consumer grade digital cameras and modern SLR's in this article, since it's really beyond the scope here.

Comparing image quality demands for a lot of examples, therefore this article contains quite a lot of images so please be patient if you are using a modem connection.

Frame sizes
Below you'll see a comparison of relative film-sizes or to be more precise "image capturing areas".
It's simply the same subject matter photographed with a 6x6 camera a 24x36mm camera and a digital camera.

2.25″x2.25″ (aka 6x6) frame.

24x36mm frame.

CCD.

To left you'll see a 2.25″x2.25″ (aka 6x6) medium format slide, in the middle a 24x36mm (aka 35mm) slide and to the right a 1⁄1.8″ CCD chip.

Compared
I've shot the same scene with three different cameras : A Rolleiflex 2.8GX (6x6), a Nikon F90x (24x36) with a 50mm f/1.4 lens and finally a Canon G1 3.3mp digital camera set to capture in RAW mode so that no details are lost due to in-camera compression of the image.


3.3mp Digital File shot with Canon G1

The highlighted areas are shown in full size, actual pixels, below.
The 6x6 and 24x36 slides where both shot on Fuji Provia 100F slide film at 1⁄125 sec, f⁄11. The exposure of the digital image was 1⁄50 sec., f⁄8 (at ISO 50).
I've scanned both slides on the Minolta Dimage Scan Muli Pro scanner. This scanner is capable of 3200 dpi in medium format (6x6) and 4800 dpi on the smaller 24x36 slide.

File sizes:
Scanned at 3200 dpi the medium format slide produces a file of about 150MB.
Scanned at 4800 dpi the 35mm slide produces a file of about 90MB.
The uncompressed 3.3mp output from the digital camera produces a file of about 9MB.
(All files sizes are in 24bit color mode).

So why not simply compare the scans at highest optical resolution to begin with?

The antenna in the left side of the picture:

Medium format at 3200 dpi

24x36 at 4800 dpi

When scanned at 4800 dpi the smaller 24x36 frame becomes almost as big as the 6x6 frame (approx. 7200 pixels vs. 6800 pixels in the horizontal direction).
Although the exposure is identical for the two frames the medium format frame is actually a little bit overexposed, because the light became a bit more intense, resulting in a somewhat lighter image. I've tweaked the levels a bit on all images using Photoshop.
There is beyond doubt more details in the medium format frame.
A bottle on the left side of the veranda:

Medium format at 3200 dpi

24x36 at 4800 dpi

A plant standing in front of the veranda:

Medium format at 3200 dpi

24x36 at 4800 dpi

Again more details in the medium format picture, however the slightly overexposed medium format frame actually shows more pleasing colors, which might influence our judgment of details a bit.

A book standing on the stairs:

Medium format at 3200 dpi

24x36 at 4800 dpi

Clearly more details on the medium format picture - we can read the letters "Gardens" and "France" which is rather difficult on the 35mm frame.

But was does the 35mm picture look like, when scanned at 3200dpi like the medium format picture?

Medium format at 3200 dpi

24x36 at 3200 dpi

I've compared the medium format slide to the 35mm slide scanned at 3200dpi here, but when scanning at 4800dpi you do actually get a little bit more information out of the slide. See the "4800 dpi on 120 film" article for more details on this subject.

What about the digital images?
Well, there is no need to compare them side by side with the scanned slides, since the resolution is so much smaller.
Let's have a look:




Again colors are different from the scanned images. The picture suffers from some color fringing, which is especially visible on the antenna.
If I upsample (enlarge) the digital file to somewhat match the size of the 24x36 frame, it will look something like this:

24x36 at 4800 dpi

3.3mp digital file upsampled approx. 3 times

No sharpening is applied. Needless to say that the 35mm scanned image contains a lot more details.

What else?
Clearly the kind of image quality and resolution you need depends on the photographic application and what the output media is.
This comparison could have included a print example also - but that will have to wait for a later update.

Conclusion
The three cameras used in this test are very different to say the least. They serve different purposes and they are very different in use, so this comparison must be seen as a comparison of the quality of the image files only.
While the 35mm and the medium format frames are easy to compare, it becomes impossible to compare them with the digital file, since the resolution is so much smaller. This is not to say, that digital files always has a poorer quality when seen on the final "output". The digital camera used here is a consumer camera NOT a professional digital SLR camera. Follow links below to see the output quality of the newest DSLR's.
In addition to answering the question asked in the beginning : "What digital image quality will I get from a consumer grade digital camera compared scanning slides from a 35mm (SLR) camera" this test could also answer another much more specialized question, namely : "How does scanning 35mm 4800dpi compare to scanning 3200dpi medium format on the Minolta Dimage Scan multi Pro?"(!) As can be seen from my little test, the answer is simply that you still get more details from a medium format slide. But then you would also have to take into account, that the Nikkor 50 f/1.4 lens used here is very different from the Planar 80 f/2.8 used on the Rolleiflex.
So, all in all this was just a little guide in image quality and resolution from three widely used "formats" today (medium format, 35mm and the small consumer CCD)!

Links
[Update 11.06.2003]
See my new article comparing the new Canon 1Ds with scanned 35mm film.
• Canon 1Ds vs. Film - 35mm

[Update 10.12.2002]
Visit Outback Photo to see a comparison of the new Canon 1Ds versus scanned 35mm film. As you will see, this camera outperforms scanned film.
• Canon EOS 1Ds Experience Report

As always, The Luminous-Landscape authored by Michael Reichmann is a good place to visit for information about almost anything concerning photography and especially the digital darkroom:
• Canon EOS D60 vs. Medium Format
• D30 Vs. Provia 100F

Brian Tao :
• Canon D30 output vs. scanned Provia 100F film

Roger N. Clark's Photography:
• Image Detail - (How much detail can you capture and scan?)
• The Digital Print Advantage

Another comparison of 35mm scanned at 4800dpi vs. 3200dpi mf can be found in this Contax TVS III review:
• The Contax TVS III: A Review (and Comparison)