Resolution of film vs digital

[Tom_Henderson]

I recently had to do a photo of a city skyline that was going to be blown up to 20' wide and hung in a restaurant. People were going to be able to walk right up to it an look at it closely, so resolution was very important. I did a lot of math (which I'm not good at!) and concluded that my best bet was to break out my old 8x10 camera and shoot it on transparency film. That project is now in the works and looks good so far.

But it inspired me try and figure out some kind of comparisons between film and digital. Film is tough because it always has grain which looks sharp, and digital just keeps getting softer and softer.

But I had done some other comparisons a few years ago, so I dug back in my files and compared a shot done on 35mm trans, 2¼" trans and an EOS1ds 11 mp camera. The transparencies had been scanned at very high resolution to capture all the detail possible. Any finer scan would have just shown more grain.

After comparing small sections (4x5") cropped out of the original images I have come to a conclusion.

2500 pixels (in any direction) is equal to 1" of film (in any direction). You can do your own math to get an overall megapixel count for the chip. But I think this gives a very useful comparison when looking at the pixel x pixel count of a chip. Now I can look at those numbers and see what their equivalency in film might be. For example, my Phase 1 H25 back is 5440 x 4080 pixels, which is roughly equal to film that is 2" x 1.6". And here I was telling myself that it was almost as good as 4x5" film!

Here's a link to my test photo. I did this for myself so details may be a bit sketchy. If anybody really wants to know more, let me know and I'll elaborate. http://www.tomhendersonstudio.com/Pa...olution_02.jpg

I'm also curious to know if anybody else has done similar tests?

[Noel_Carboni]

There is no easy answer to this, as demonstrated in debate after debate of film vs. digital, which have kind of died down now with the latest digital cameras. However, your figures agree pretty well with the sentiment that a 35mm frame has about 10 megapixels of info in it.

There are some pretty sophisticated methods for upsampling that don't have digital "getting softer and softer", by the way. Check out the latest release of Genuine Fractals, for example.

By the way, a way to get a great deal of resolution/size out of a digital camera is to take multiple images at higher focal length and stitch them together to make a mosaic. Do a web search for "the world's first 1 gigapixel" image (of Bryce Canyon) and you'll see an extreme example of this.

-Noel

[Oyvind Nikolaisen]

One way of getting around the resolution challenge is to shoot multi-row panoramas. Not entirely satisfied with the resolution of a stock D1X or D200 image when printing 50x20 panoramas, I compensate by shooting multi-row panoramas and stitching them together using PTgui.

If you have a look at http://mail.kingsbay.no/showcase - you will find an image stitched together from three rows of nine pictures each. The end result is a 123Mp panorama, 18100x6900, quite suitable to print in at least 5x2 feet - more using GF or similar.

Although the gigapixel image is rather interesting from a technical point of view, you will run into difficulties with moving shadows due to the sheer number of images you have to shoot in order to get that kind of resolution. Shooting anything where moving objects have to be part of the finished product, precludes this approach - maybe keeping your good ol' 8x10 is still a good idea?

Øyvind

[BobSmith]

Originally Posted by Oyvind Nikolaisen

One way of getting around the resolution challenge is to shoot multi-row panoramas.

I did exactly that for a job much like what the original poster describes. I was hired to photograph the interior of a basketball arena. The resulting print would be used to cover a wall 17 feet wide as decoration for a game room. I photographed the arena with a series of 27 shots (3 rows of 9 frames each) using a 105mm Micro Nikkor on a Kodak 14nx. I shot from near the top of the area. In the finished print you could count the cords in the net on the goal... or read the numbers on the seats on the far side of the arena. Plenty of resolution. I use either PTAssembler or PTMac to stitch my panoramas. Once you work out the technique, it can be done with reasonable efficiency.

Bob Smith

[LarryLetzer]

Oyvind, That is one amazing photograph. Congratulations.

I am a people photographer. How do you do this with people?


Bob, Would that be a photo of the Baylor Fieldhouse?

[David_Buzzard]

I'm lousy at math, but I can tell you from practical experience that digital kills film. I had a chance last summer to do some 16x24 prints on an Epson 4800, and with JPG files (I didn't have a computer with a decent RAW converter) from a Nikon D2x, the prints were at least as good as what I could get from a conventionally printed 6x7 colour neg. I've been going through some files scanned from 35mm slides, and they don't even compare to my old D1x files.

When you see what something like a Phase One back on a Hasselblad can do, you'll be a true believer.

David Buzzard's Technical Blog

[BobSmith]

Originally Posted by LarryLetzer

Bob, Would that be a photo of the Baylor Fieldhouse?

yes. this was done a couple of years ago around the time the women won the national championship. An alum in another state was adding a large game room to his house and came up with this idea for part of the decor. He got the idea from a photo that appeared in the local Waco newspaper showing the empty Ferrell Center arena. The newspaper sent him a copy of their file (taken I think with a D1x). What looked great in newsprint somehow just didn't look quite right blown up to 17 feet wide! And unlike a billboard meant to be viewed from a great distance, people would experience this print while standing right next to it. The Trib photographers told him to contact me about recreating the shot with his usage in mind. The finished print was done by a biillboard company and installed in Arizona. I've never seen the full final product but the customer was pleased.

I've used stitching techniques a couple of times on photos of a group of people where we knew the ultimate goal was a large print. It's not too difficult to do. Shooting with lots of overlap gives you ample ability to edit the layered images so that people moving near the seam don't affect the final result. A really good tripod head made for this type of shooting helps tremendously as it lets you shoot the series quite quickly.

Bob Smith