A Graflex Super Graphic 4×5 camera with lenses popped up on Craigslist for $125. The seller, a photographer Timothy Wilson, explained that he no longer had time for the camera. He knew the price was a bargain (Thank you, Tim!). After buying it, I began to research and discovered that other tinkerers are breathing new life into the 4×5 format. New55Film is manufacturing instant film, which can be used like the now-defunct Polaroid 55. They also sell film and single-bath (monobath) development kits. Timothy Gilbert is developing a painless 4×5 development tank through Kickstarter, the SP-445. I’m happy to learn that if my experiments fail, I have options in film.
My goal with the Super Graphic was/is building a low-cost DIY digital back–a high speed one preferably, for portraits! If a 4×5 digital sensor exists, it must cost a fortune. The least expensive medium format camera (2 1/4 inches) runs around $7,000 without lens, the Pentax 645Z. Professional medium format photographers typically use $50,000+ worth of gear.
My goal was some sort of raster-scan digital back using a mirrorless camera, like the Sony A7. Fotodiox offers a few adapters that allow one to use a Nikon, Canon, Pentax or Sony A-mount on their 4×5 camera, using one of these adapters. Here’s a more sophisticated Vizelex Rhinocam from Fotodiox for medium format. I have many Fotodiox Nikon/Canon/M42-mount to e-mount adapters for my Sony cameras and they are great value for the money. However, there are some limitations to their Rhinocam-type solutions which I’ve always had an itch to solve!
For starters, I had to determine how difficult it was to get anything workable. This was my first model
From my first attempts I immediately noticed the benefits of higher resolution, less chromatic distortions from bayer sensor images.
The general idea behind the approach is to create a virtual 4×5 sensor (102mm by 127mm) by tiling a full-frame digital sensor (36mm by 24mm). In a perfect word, we could place our digital camera sensor 16 times to capture almost a full 4×5 image:
Unfortunately, we can’t be certain that we can align each exposure perfectly, where there isn’t missing space between tiles. To be confident that we’ll get the whole 4×5 image, we’ll need software to figure out where our images overlap so it can “stitch” them together. The more overlap we have, the easier it is for the software to create the composite image. Generally 50% overlap is safest. Therefore, a real world capture pattern is this:
The corner and center tiles are transparent, so you can get a better idea of what’s going on. Essentially, there is some overlap between all images. We need 30 images, double our theoretical 15 full-frame shots (102 x 127 = 12,954mm, 36 x 24 = 864mm; 12,954/864 = 15).
Anyway, I attached the A7 to the black board, held it against the white board that was attached to the Graflex (w/Nikkor W 180 f/5.6), fitted with a 4×5 picture frame on the other end. The grid helped me position the camera in a way to expose a grid of 5×6 overlapped images.
I was very excited! The free Microsoft Image Composition Editor (ICE) stitched the images together well.
Then the honeymoon ended. The biggest obstacle to stitching-based large-format photography is subject and/or camera movement. Here’s a shot where a combination of the camera moving (disconnected girders in background) and my (sliced arm), result in a “problem” photograph.
(Nontheless, this was the first attempt my friend Mark Wylie made using my crude device on a gravel surface!)
I have yet to figure out the best approach with stitching software; each has its benefits and drawbacks. For now, I’ll just list the options, with what I know so far. In freeware there is Microsoft ICE (link above). ICE’s “structured panorama” visual tool is the best approach for this type of stitching in that you can see what it’s doing.
For a cross-platform solutions there is Hugin. Other commercial solutions are PTGui, Easypano. Adobe Photoshop will also photo “merge” images. The problem with the non Microsoft ICE solutions is they don’t have a strong “structured panorama” approach to image stitching; indeed, ICE is almost perfect in that regard. Most stitching software assumes you’re a panorama head and uses the focal length of the lens to pre-calculate stitching parameters. I’m hoping that I can use a tool like ImageJ to create scripts where I can say, ‘these are the exact placement of these images so please stitch from there’. It’s a lot to do. Or, I may figure out a fool-proof procedure in ICE.
In the meantime, I’m working in improving the digital back so that I can take 30 shots as quickly as possible. The faster that can be done, the more one could use this method for portraits.
Here is a link to a Flickr album I have set up for this project. Thanks to Mark Wylie for shooting the video above!
I’m working on a 3rd version of digital back. Part II of this coming soon. I hope!