So I am trying to take two pictures, one with a DSLR and one with an iPhone 7. Why an iPhone 7? That's just what I own currently I want the photos to be aligned so that they are exactly the same. The camera and iPhone will mounted on a tripod using a stereoscopic tripod mount like this, the iPhone using something like this.
The idea is to place the iPhone and the DSLR on the tripod and take the photo, then algorithmically align the photos. I do have a few concerns because I am somewhat new to photography...
This is for a research project so I can use cameras on loan from my university. Here are the camera & lens combos I have available with their specs:
- Canon 80D w/ a Canon 18-135mm EFS Lens
- Canon 70D w/ a Tamron 18-200mm Lens
- Canon 80D w/ a Tamron 18-200mm Lens
And it says online that the iPhone 7 has the following specs:
Sensor: Sony Exmor RS (1.22 µm, 1/3")
Focal Length: 4mm (28mm eff) 8mm (56mm eff)
Max Aperture: F/1.8
So my question is, what variables do I have here that I need to keep in mind. The first one is horizontal displacement seen here in a crude mockup using stock photos. This I think will not be too much of an issue. My one concern is that parallax will make the overlapping part not actually be the same exact photo and there will be some noticeable difference. That would be a problem.
The second problem is the one I have no idea where to start with: lens distortion. This is due to aperture and focal length, right? Theoretically, if I manually set the iPhone's focal length & aperture to be the same as the DSLR's(which is easily done using photography apps), will the pictures turn out to be exactly the same?
How should I start going about doing this? These both are big problems that I really want to know how to address most easily. I want to take lots of photos side by side and I'm trying to figure out a workflow/setup that will make aligning the photos as easy and accurate as possible. I'm just looking for guidance so I can know where to start, what to buy, and how to set things up somewhat professionally.
Feel free to ask followups if I left any important details out.
- This is for a ML project where I am trying to use DSLR images as ground truth to improve iPhone images. It's a recreation of this research. What they use is a linear transformation and cropping, which is very similar to @xiota's answer (You are a smart person, I'm glad I got your help :))