What are the optical advantages of MF over 35MM SLR - Found?

Hello, I posted this subject some time back, and since then have got
myself an old Box brownie to compare the image of the 35mm Film SLR and
the Brownie for differences in ratio of FOV between the foreground and
background. The differences are interesting, but can anybody with optical
design experience tell me what is happening here?


The Brownie:

http://members.home.nl/brownies/six_20_brownie_d.htm

f/11, 100mm, lens, 2 1/4 * 3 1/4 inch film size. Focused on Infinity.

The SLR, a old body cobbled together (tight but good fit) with a Minolta
1:1.4 55mm lens.

Rear focusing screen made of opaque plastic, and stuck on the back of
both. I wanted to post images with the digital on the web, but the focus
screen hot-spot on the Brownie is so bad, small and dim, that it was
pointless to try.


The Test:

I used plastic bottles as markers. I put the markers around 30 feet from
the camera to each side of the frame of one camera and with the peaks of a
mountain range several kilometers away in the background. The cameras were
mounted on top of each other (the brownie on it's side) on top of a short
wooden step ladder.

Result:

Not much difference between the FOV of the mountain range above the
markers in both cameras. With the very dim MF image (and I was under
shade as well) it was very difficult to see the image clearly. I repeated
the experiment with the markers now around 15 feet away, still no much
difference. The overall Field of View was significantly better on the MF
lens.

So the experiment seemed to confirm that there is no difference in the
ratio of foreground FOV to the background FOV, between the MF and the
35mm. But if there were differences they were too small to see clearly
with the focus screens. But then I tried again.


Another experiment:

I originally was going to rig up two pieces of paper a few feet away to do
the experiment, but it was very windy. It then occurred to me that I
could use two bottles in front of the cameras to form a slit.

With bottles set apart by 2 centimeters to make an slit opening, with the
distance of the far opening of the slit the approx the same several
centimeters from the lens glass openings on both cameras, there was
substantial difference in the FOV of the mountain range through the slit.
When the cameras backs were the same distance, instead, the FOV was a
bigger difference with maybe double FOV through the slit in the 35mm then
the MF. But, the closeup slit itself, on the 35mm, took up around 1/3rd
of the image plane, and 1/6th of the plain of the MF. Does this imply
that the MF Brownie has more closeup FOV that the 35mm. A bit confusing,
I thought the long distance FOV might be smaller on the MF instead. What
do you think, it is not the most accurate experiment, can anybody verify
this? I am interested if MF FOV does anything to give a truer, to the
eye, image.

Thanks

Wayne.



On Sat, 15 Jan 2005 19:50:06 +1000, Wayne wrote:

Hi

If there is any optic technician/expert that can help me with affirmed
knowledge, please reply, it will be most appreciated. I have spent time
trying to research this on the web, but from what I can tell:

- That the only advantages are professionalism, extreme narrow DOF and
higher resolution.

That the following does not improve compared to 35mm SLR:
- The size ratio between foreground and back ground objects
- Angle of view
- convergent lines and shape distortion of receding objects
- curvature from wide angles (i.e. producing normal looking images with
straight lines)

- That the only way to solve these problems is through, shift, tilt,
swing lenses and altering distance/perspective?

Also does it produce a flatter image or more out of focus effect simular
to a 35mm zoom lens?

Is all this true?


Thanks

Wayne
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