Comparing the Image Quality of Film and Digital

 

There have been a few film versus digital articles here and there on the interwebs, but seems like very few have approached the subject in a scientific fashion or with the advice of both film and digital experts.

However, with the help of Joe Cornish (a landscape photographer who made his living shooting on medium and large format but now shoots Phase One IQ280s), Chris Ireland (who sells Phase One cameras), and myself, Tim Parkin, (I shoot film and run a drum scanning service), a definitive test was born.

The first part of the test compared large/medium format film with medium format digital, and a subsequent part was a comparison of high end DSLRs using the Nikon D800E.

The results may surprise a few people.

Here’s our comparison of the Nikon D800E and a Mamiya 7 medium format camera (both using ~25mm equivalent lenses):

Nikon D800E DSLR (left) and Mamiya medium format rangefinder (right)

First of all here’s the full photo view showing the cropped area we’ll be looking at:

And here are the comparisons in color (Fuji Velvia 100F) and black and white (Adox CMS 20) film:

We were that impressed with the performance of the Mamiya against the D800E in terms of resolution that we thought we’d try comparing with the IQ180.

The Phase One IQ180 packs an 80-megapixel sensor.

Firstly the color comparison:


Okay… Even though if you look closely at the way the Mamiya 7 resolves the text it looks comparable, the overall impression is that the IQ180 has the sharper, cleaner image. This is due to the fact that high resolution details in film get lower contrast, whereas on digital, everything resolved appears at a fairly high contrast.

Let’s look at the black and white results. The first image is the IQ180 and the second is the Mamiya 7 at f/8 (ignore the third for now):


Wow! Now the film used is Adox CMS 20, a high resolution film capable of resolving 800 line pairs per mm. In real world tests (by Henning Serger) this film on a Mamiya 645 with the 80mm Sekor has resolved 210 line pairs per mm which is greater than 24,000px across the film height!

In other words, this is a potential 400 megapixel result, but when scanned a lot of this is lost and you get about 50 to 80 megapixels. It’s still very impressive though! The results from our Mamiya 7 suggest about 150MP. Projected (as a black and white positive) or enlarged and you’ll get a lot more.

You might be wondering what the third frame was in the above image. Well, it’s the Mamiya 7 at f/22! This goes to show just how good old lenses actually are (especially the Mamiya rangefinder ones) and on a sideline proves that f/22 isn’t the hellhole that many photographers believe it is (for more about that refer to Roger Cicala’s article about diffraction).

What About Large Format?

Here are a couple of comparisons between 4×5, 10×8 and the Phase One IQ180. This first is a section from a transparency that was placed on a lightbox (see the studio overview shots above – it’s the bottom left transparency). Here’s the full transparency and then a section from the left hand fork of the branch. Here’s the whole view for reference:

…and a sample showing just the part of the table of interest. We’ll be comparing results from the red area.

And here’s the final comparison. From left to right this is the IQ180, 4×5 Velvia and 8×10 Velvia:

4×5 shows better performance than the IQ180 and the 10×8 just blows everything out of the water.

Finally, here’s the real world landscape photograph that we took on a windy day in Yorkshire (that happens a lot!). We’ll be showing a comparison of 4×5 and the IQ180 for the area marked in red on the left hand side of the picture:

Here’s a comparison between the IQ180 and 4×5 Velvia 50.

As you can see it’s a close call. Some things look more refined on the 4×5 Velvia (the garden chair, the car grille) and some things look a lot clearer on the IQ180 (the garage roof and walls). In a print of this section things were ranked pretty closely.

Why are the results from 4×5 not performing as well as indicated by the studio comparison? Well in the real world we had to stop down from our optimum aperture of f/11⅔ to about f/22. This reduced the max resolution of the 4×5 shots. The IQ180 needed stopping down too but that just reduced the contrast at the sensors maximum resolution and with a bit of sharpening it didn’t really do much damage.

What About Color Rendition?

One of the interesting things that cropped up was the way that the digital sensors deal with color in terms of tonality and resolution. Because only one in four pixels are blue or red, quite often color resolution is reduced in comparison with luminosity resolution. These look fine at small enlargements but when images are shown larger these artifacts can show through.

Here’s a great example of the problems with having only a few red pixels from an outing a few years ago, comparing a Canon 5D Mark II with 4×5 Velvia. Obviously the 4×5 Velvia has more resolution but we downsampled it to match the 5D Mark II and got the following result (show at 200%)

On the right (the 4×5 image downscaled) we can see all of the berries on the tree but on the left (the Canon 5D Mark II image) a lot of the berries have disappeared. The only berries shown are where there were larger groups of them (i.e. a single pixel size berry is unlikely to match up with a single red pixel whereas a group of berries covering 2×2 sensor pixels will definitely hit a red filtered one).

Also film still seems to differentiate color differently to digital (depending on the camera). Here’s a sample of our test image from the cyan boxed area at the bottom next to the pond.

On top we have a 4×5 Portra 400 scan and on the bottom the IQ180. The 4×5 Portra 400 version has much more color definition.

So What About 35mm Film?

We didn’t include 35mm film in the test – it was originally aimed at comparing 10×8 film with the IQ180. However, I had a recent scanning job for a colleague of mine who has taken 35mm film cameras to some of the highest mountains in the world (Alan Hinkes – the UKs first mountaineer to climb all of the world’s 8000m peaks) and he has allowed me to show a photograph here including 100% crops. These photographs were taken using a Ricoh GR1 on Fuji transparency film. We’ve enlarged this to 15″ x 30″ recently.

Here’s a 100% of the scan at 6000DPI:

The results are very impressive and from our comparisons we think scanned color slide film has a digital equivalent resolution of between 12MP and 24MP depending on what aspect you look at (12MP for overall sharpness appearance, 14-16MP for luminosity resolution, and 24MP for color resolution). These figures are estimates based on a good Imacon or Drum scan and would be even higher for projected or enlarged images.

And here’s a final one showing the dynamic range of Portra 400 on a 35mm camera. In this case an Olympus OM10 that I bought on ebay for around $30. The dynamic range in this scene was measure as 15 stops and there are no areas that are blocked up or blown out.

Conclusion

Film still has a lot to offer, especially with the price of very high quality cameras so low. Using high resolution black and white film is well documented these days (although you have to process them yourself) and the latest version of slide and negative color film are stunning. Portra has been reformulated for scanning and has immense dynamic range and Fuji Provia is one of the highest resolving slide films ever made.

As for scanning, film scanners can be had for reasonable prices, even drum scanners! And finally medium format drum scans can be had from $20. My conclusion? It’s a great time to be using film AND digital!

---

P.S. If you want to see some more information about our film versus digital tests, please visit this page.

---

About the author: Tim Parkin is the editor of a dedicated landscape photography magazine On Landscape and also the CEO of a drum scanning business. Whilst not in front of a computer writing and post processing he can be found in the Yorkshire Moors with his 4×5 or 10×8 view camera and A7R.

Original Post from  :http://petapixel.com/2014/12/18/comparing-image-quality-film-digital/