Lens Focal Length Comparisons (Academy vs Medium Format)
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- Created on Wednesday, 04 June 2008 21:00
- Last Updated on Friday, 14 December 2012 20:15
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These are a few pictures I took on June 5th, 2008 to compare the different focal lengths and the angle of view of the lenses I had. The lenses used in this test were:
Jupiter 4/135 (135mm) - OCT18 mount
LOMO OKC6-75-1 1:2 (75mm) - OCT18 mount
Biometar Carl Zeiss Jena 2.8/80 (80mm) Pentacon Six adapter to OCT18 mount
The cameras used were the Konvas 1M and the Pentacon Six Medium Format camera. All lens apertures were opened as wide as they could go to allow me to snap pictures through their viewfinders.
I took an outside picture (wide) with the digital Nikon CoolPix camera I had been using, just to show the exterior test area:
This one was mounted on the Pentacon Six TL, a medium format camera. I used the built in magnifier on the top of the camera to aid my Nikon in taking the picture (there wasn't much of a difference between the look I got with the magnifier and the look without). I was focused on the row of bushes:
These three were taken thru the viewfinder of the Konvas 1M. This particular viewfinder still has the VF matte in place, and since I never adjusted the matte properly (I rarely use this viewfinder), I decided to turn the matte vertically, so there is some cropping on both edges. These were also focused on the row of bushes:
The following were of my son in the kitchen while he was eating. I turned them to Black and White, as the colors were completely off and blown out, and the images weren't really all that great due to the low light:
And these are to show the different focal lengths and the angle of view of each of the lenses on their respective cameras:
.jpg "80mm medium format frame (60x60mm)")
.jpg "50mm lens and 135 still 35mm film (36x24mm)")
Although the 35mm lens pic below may have been out of focus, please remember that this set of pics were only meant to show the field of view...
.jpg "35mm lens and motion picture film frame (22x16mm)")
Lastly, this is the 80mm as taken on the Medium Format Pentacon Six. The inside image was taken with the same 80mm mounted on the front of the Konvas (ie., Motion Picture Academy Frame).
Konvas and Kinor owner HW Stone had this to add:
80mm is 80mm is 80mm
On a 4x5 inch negative it is one angle of view, on a 6x9cm negative it is a narrower angle of view, and on a 18x24mm negative it is a still narrower angle of view-- BUT IS STILL THE SAME IMAGE OBJECT SIZE. If you put a block dead center that almost filled the frame for the 18x24mm, photographed it, then repeated the same object at the same distance with the 6x9cm and 4x5 inch film WHEN YOU MEASURE THE ACTUAL SIZE OF THE BLOCK ON THE FILM it is identical-- a 16mm tall image of the block on the 18x24mm negative is still 16mm tall on the 6x9cm or 4x5 inch film.
You simply have a lot more empty frame around it.
As well as this:
"the angle of view of a 6x4.5cm negative produced by a lens of 80mm focal length as compared to the angle of view of a 18x24mm produced by a 45mm focal length lens shows an apparent similar composition, although every image object is of reduced actual negative size on the smaller frame as compared to the larger frame" would be correct.
The ratios also change as you focus more closely than infinity. The "depth of field" is actually a function of angle of view, btw, and if you want to have some fun take a super wide angle negative and print only a very tiny center segment, the angle of view equal to a long focal length lens you have used to photograph the same view. The "depth of field" on the segment is exactly the same as the longer focal length lens, even though it appears that there is more depth of field in the wide shot.
Angle of view is not well understood by most working photographers, but vital for good cinematography.
There's a reason that the DP is usually the oldest guy on the set.
Thank you, Mr. Stone!
BTW: I should note that all of the above pictures were taken with my Nikon thru the viewfinder, and the Nikon was not mounted even remotely properly - it was just me putting the Nikon up against the viewfinder by hand and snapping a picture - so ALL of the vignetting and dark corners you see are because of me holding the camera improperly and NOT because of any of the lenses had vignetting! Also too, this is not rocket science, nor exact scale - the images may be warped or otherwise mis-represented due to my care-free camera practices...
For more lens related information, read the article by H.W. Stone: "Comparing 35mm Still Camera Lenses versus 16mm & 35mm Cine Lenses".