Folder view finder accuracy

While out shooting some public murals a couple years ago (of course, everything was a couple years ago!), I found this one that almost exactly fitted the viewfinder of my pre-war Zeiss 6x4.5 Super Ikonta 531. This happened to be about the first excursion with this camera and I was curios to learn just how the photograph would compare to what was in the view finder.

The camera was on a tripod with the head rotated 90 degrees to the right. I aligned the right side of the mural with the "top" of the popup framing viewfinder and placed the tripod so the other sides all fit as perfectly as I could.

I guess that answered that question...

Yeah, about to be expected. This kind of thing made me understand why so many family and tourist snapshots from the first half of the 20th century have people or important sites at about the center of the frame with fair slop room around the edges if possible. I'm sure people got an earful the first time fancy photos of the family reunion picnic from the new expensive camera came back and Aunt Hilda was missing off of one side and Uncle Bob's head was sliced off.

One thing with the Zeiss folders (and others, of course) is how much eye position can affect what the viewfinder shows.

I'll take mental notes for a frame or two with a new folder. "Bottom edge of viewfinder is aligned with picnic table base." And then look at what ends up on the actual film. You might find that using one edge as a key line is actually pretty good, it's just figuring out which edge.

Best bet- take some ground glass, open the lens up, and do some comparisons of the viewfinder image and the actual film image. If not- keep Aunt Hilda far from the edges! And oh yeah, relax on ever getting precise framing. If you need that, get a view camera or an SLR.

Thank you for mentioning eye position. I forgot to relate that in this case (and my normal practice now) I placed my eye so that the rear rectangle aligned with the lines on the albada glass and with the mural edges.

Ikonta finder's are hopeless especially when you're wearing glasses, that's why I gave up using them - Mamiya-6 is a bit better.

As mentioned, it may just be a matter of getting used to where to put your eye when framing. You have a well engineered and built camera, so see if your viewfinder somehow got knocked out of alignment. W/ folders, I usually put them on a tripod and ck this sort of thing at different distances to get a feel for where I'm supposed to point the camera. They're all different in their viewfinder accuracy, or lack thereof. The worst ones I owned were the Voigtlander Bessa II and Bessa RF models. Their viewfinders were way too small. About as bad as a Kodak Retina.

https://www.petrakla.com/pages/albada-viewfinders

There is obviously left room to play if I understand your explanation right and according to my own experience with quite a few popup finders.
You are supposed to kind of imagine a viewfinder frame in the finder.

If finder accuracy is important to you, stay away from all old (1930s-1950s) folding cameras with direct in-body viewfinders.

Many years ago I read an article or book by someone authoritative in these cameras (publication details long forgotten, my apology for this) who made the remark that almost all built-in viewfinders gave at best 80%-85% true view. The direct (known as 'Albada') finders were somewhat better, averaging about 90%.

Perhaps the more expensive rangefinder cameras probably give close to 100%. According to the booklet my Contax G1 shows about 99.something of the actual scene. The Mamiyas MFs are most likely the same.

You may want to investigate the small spirit levels sold dirtly-cheaply by China sellers on Ebay. These fit into a camera's flash bracket (many older MF folders often don't have such a bracket) and help you to keep the camera as horizontally levelled as you can get it. Using a tripod with this is essential. I have one such finder on my four G1s. I cannot say they have seen much use, but needs must.

When there is a will there is usually a way, said way likely to be found on Ebay.

Put your camera on a tripod, then take some scotch tape (not the clear-- the semi-opaque) or wax paper, and put it in the camera with the film door open, as close as possible to the film plane. You'll want to cover the entire exposure frame. Point the camera at a bright scene.

Now you should be able to look through the viewfinder, and compare it to the image on the paper/tape, and figure out the offset / coverage.

As noted above, most viewfinders should cover slightly less than the whole frame, so that parallax doesn't remove details from the image-- but it depends on the viewfinder, and the camera geometry in general. Since I use a Bessa I with a Vaskar, I assume anything near the edges is going to be a bit soft anyway.