Welcome to the world of large medium format digital without a medium format camera. This adaptor from Fotodiox stitches 4 shots together using a convenient rotary action to create square crops from 645 medium format. Actually, slightly larger, as it makes 46mm * 46mm frames compared to the 42mm square crop from 645.
In reality, It’s just a stitching tool, and the end result is the same as any other flat stitching method, but it makes the capture process extra fast and convenient.
How does it work?
The Vertex is a rotary flat stitcher. This means the lens is held still (the Vertex attaches to a tripod using its own arca-swiss plate) while the camera body is rotated through a full circle as you take pictures at the 12 o’clock, 3 o’clock, 6 o’clock and 9 o’clock positions.
If you look carefully at the picture above, you’ll see the camera mount end is offset from the centre line of the Vertex and this means as the Vertex is rotated, the full frame sensor orbits around the centre line of the optical circle (with a bit of overlap). Essentially, you move the full frame sensor around the 4 quadrants of the 645 lens optical circle to capture a 46*46 mm section from 4 shots.
Because this is a rotary action, it feels straight forward and natural (and quick!). There are many stitching techniques, but I find this one convenient.
Variants
The growing Vertex family now has version for simulating 645 square from full frame cameras, for simulating 6 * 6 square using a mini medium format camera as the base, and there are even adaptors for crop sensor cameras to emulate full frame. There are a wide range of camera mounts and lens mount combos available.
I have the full frame version for Sony cameras and Pentax 645 lenses.
This allows me to create 100MP bigger-than-645-medium-format-square-crop files by stitching 4 images from my A7rii. The stitched files from the Vertex have 2.5x more megapixels than a single frame. Using a A7Riv as the base would yield whopping 150MP square files.
The viewfinder problem
One issue with stitching frames to emulate a larger format is the lack of a viewfinder to preview what the stitched composition will look like. You can focus and set exposure based on one frame but not so easy to compose the stitched result before capture.
One solution I tried was a Helios hot shoe optical viewfinder. This has frame lines for common focal lengths. But it’s not great quality and framing is a bit approximate (to say the least).
I’m currently experimenting using my phone as a viewfinder. There are various “Director’s viewfinder” apps available for Android and iPhone that will simulate the view on your phone using the phone camera for various sensor formats and focal lengths. I have an inexpensive clip on grip for my phone that has a tripod socket. I attach it to the camera using a cheap hot shoe ball head.
Field workflow
My current workflow;
- Attach the Vertex to my Sony, attach a 645 lens to the adaptor, then bolt the whole contraption to my tripod head using the Arca-Swiss foot built into the adaptor. This allows you to rotate the camera rather than shifting the lens and avoids the parallax issues with nearby subjects that comes from moving the lens as you might with conventional sideways shift lens flat stitching.
- Clip my phone to the hot shoe and start the director’s viewfinder app running. This uses my phone cam to simulate the final stitched frame for composing.
- When I’m happy with the composition, I open the lens wide open, magnify to 12x and focus. Then I stop down the lens to the chosen taking aperture (I’ve used f/11 and f/16 in my initial experiments).
- Rotate the camera until the frame is mostly filled with the brightest area of the composition eg the sky, and set exposure for this to avoid clipping. Make sure you lock exposure, focus and white balance for all 4 frames to make stitching easier.
- Rotate the camera back to the 12 o’clock position, ready to start. I have my camera set to 5 second self timer to leave time for vibrations to die down. I take a shot of my hand to mark the start of the sequence.
- Take the first shot, rotate the camera 90 degrees, take the second shot, rotate the camera 90 degrees, take the third shot, rotate 90 degrees and take the final frame.
- Finally, shoot another shot of my hand to mark the end of the sequence. In future, I may replace the shots of my hand with shots of a card with the focal length used on it as there is no Exif info.
That’s it. It sounds involved written down like this, but in practice it is quick and easy and soon becomes second nature.
Stitching
Once you get home to your computer, you stitch the 4 images using any pano software. For some reason, my old version of Lightroom objected to the rotated images and wouldn’t stitch them. I’ve heard later versions do work. I’m using PTGui instead, which works fine.
One drawback of stitching is the resulting very large file sizes. You can stitch to 16 bit Tiffs but I’m seeing 600MB file sizes. My computers balks at those and I may revert to 8 bit Tiff or even jpegs.
Results
These are 100MP originals downsized to 25MP for web viewing (right click to download):
Finally, use this link to download a stitched, but unedited 100MP image:
https://live.staticflickr.com/65535/52361183147_dec9587cab_o_d.jpg
Costs and conclusion
The Vertex is not a cheap adaptor, as adaptors go. And you need to own a full frame camera if you want the really big files. And medium format lenses. Nice if you already own these things but it gets expensive if, as I did, you have to buy the lenses as well as the adaptor. But it is cheap for medium format.
For example, a typical Fuji GFX lens bought new will cost something between £1000-£2500. I acquired the Vertex and 4 manual focus Pentax 645 lenses (via ebay) for £849 including all taxes and shipping. I could have halved the lens costs by going for the P645 zoom lenses but I wanted smaller lenses. The entire 4 lens outfit cost less than one GFX lens. It’s not cheap, but it is relatively cheap for medium format. And remember that the final files are 25MP larger than any current GFX equivalent.
Whether you consider this a bargain obviously depends on how much cash you have available and whether you can deal with a stitching approach. The workflow suits me because I already use my Sony for tripod mounted long exposures.
The 645 lenses will also open up tilt/shift movements to me (with a different adaptor) but that is a story for another day.
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