Wide angle and film format

[shawn]

However, people frame pictures with cell phones differently because the lenses focus closer than equivalent 135 format lenses and composition is not restricted by having to look through a viewfinder.

And very often shoot not squared up with the subject which adds tilt type distortions.

Shawn

 

[Godfrey]

I was reading an article on the B&H blog talking about the Hassy SWC cameras, and stumbled across this comment re. the 38mm Biogon:

The beauty of the Superwide is its ability to capture wide-angle pictures that simply don’t look wide-angle. They’re wide-angle, but the Zeiss 38mm Biogon renders the spatial relationships between visual elements within the frame with less perceptual distortion than a comparable wide lens on a full-frame 35mm camera.

The article doesn’t elaborate...

So, what are they on about? Does film format affect how lenses with comparable field of view render ‘spatial relationships’ - and if so how/why? - or is B&H talking out their proverbial..?

I don’t have a great technical understanding of optics, but this doesn’t quite make sense to me...

The bolded statement is nonsense. That's all.

The Biogon 38mm lens on 56x56mm format nets a very wide field of view (72x72 degrees, with a 92 degrees diagonal FoV). That's about double the diagonal FoV of a 50mm lens on 35mm FF, so it's very wide indeed. This lens delivers that very wide FoV with very close to zero rectilinear distortion (meaning that parallel lines remain parallel across the entire field of view with neither inward bowing (pincushion distortion) or outward bowing (barrel distortion)) and with very very high resolution and contrast right out to the corners (up to nearly 200 LP/mm by some reports). It also achieves rather nice bokeh on out of focus elements in the scene.

The Biogon 38mm lens exhibits the same amounts of perspective distortion (a function of the relative distances between objects and the lens within the field of view) and perfectly normal, expected wide angle distortion (the effect of off axis elements in a scene to be 'spread' across more area than their physical size and shape ought to be because of the conversion being three dimensions projected onto two dimensions). It doesn't degrade the image quality with these distortions with other negative characteristics like smearing and poor resolution as the objects approach the edges and corners of the frame.

The "comparable" focal length lens on FF format is a 15mm lens cropped to a square on the 36mm axis of the format, so 36x36 mm. The issue is that most 15mm lenses on FF have a vast host of distortions compared to the Biogon 38mm. The best 15mm lens I've found, after trying to get the SWC effect on FF and other small formats for years, is the very rare Super-Elmar-R 15mm f/3.5, which has similar imaging capabilities and qualities when cropped square. I think Leica (rather Zeiss, since the 15mm f/3.5 is a Zeiss Distagon 15mm lens made to Leica specs and lens coatings, in an R-mount) produced about 2000 of these lenses total. It's a stunning performer and produces results that are remarkably similar to the Zeiss Biogon 38 on 56x56. Very few other FF lenses even come close.

The Zeiss Biogon 38 in the Hasselblad was so special in its qualities and capabilities that Hasselblad dedicated an entire body to it for almost thirty years in production, the SWC, but that bolded nonsense from the B&H Photo article is just that.

G

 

[olakiril]

- A 'perfect' 38mm rectalinear lens* on a 120 camera shooting 9x6 frames.
- A 'perfect' 20mm rectalinear lens* on a 135 camera shooting 3x2 frames.

*or whatever fl would give the exact same fov.

Disregarding depth of field, would these two lenses render spatial relationships between elements in an identical composition the same way?

Yes the spatial relationships would be identical.

 

[nickthetasmaniac]

The Zeiss Biogon 38 in the Hasselblad was so special in its qualities and capabilities that Hasselblad dedicated an entire body to it for almost thirty years in production, the SWC, but that bolded nonsense from the B&H Photo article is just that.

Thanks for the detailed summary, and yes, that was my response to the article 🙂

 

[lukx]

A very interesting discussion in this thread. It touches on some of the rather confusing (for laymen and women such as me) aspects of optical theory.

A term we often read is medium (or large) format "look". I keep wondering what really constitutes this look, if it even exists at all.

Reading this thread, the most logical answer to me seems to be that with larger formats, you achieve the same field-of-view with longer focal length lenses, which are easier to design and thus are sharp, well corrected and low in distortion. Following this logic you'd mostly see a difference on the wide end of the focal length spectrum.

Apart from that, increased negative size results in smaller grain relative to the subject size on the negative, giving an increased impression of sharpness. And lastly, large format images may show effects of bellows movement (tilt/shift) that we rarely see on 35mm and even 120 film. This might be where some people see the "magic" of large format...

So with a slow, fine-grained 35mm film and a good lens (medium telephoto) I may achieve results that are very close to a medium format image with the same fov, similar aspect ratio, taken with a medium speed (i.e. grainier) film.

Am I missing anything?

 

[OlivierAOP]

Re: a FF-equivalent 38mm on 6x6, I think you'd need a 16mm lens at 24x24mm crop.

The large-format look is a combination of lower grain, higher resolution, smoother tones and shallower dof. The first three result from the higher magnification on film: there is more film between features of your subject, and at equal lens resolution (vs. smaller format) that means more detail.

That said I get sharper images on digital vs. medium format film.

 

[OlivierAOP]

I'll add that view lenses, RF wides and normals and reflex normals are of symmetrical type, which naturally are well-corrected for coma, distortion and chromatic aberration. Telephoto and retrofocus (i.e. reverse telephoto) can also be corrected for those, it's just more tricky.

 

[nickthetasmaniac]

Reading this thread, the most logical answer to me seems to be that with larger formats, you achieve the same field-of-view with longer focal length lenses, which are easier to design and thus are sharp, well corrected and low in distortion.

Is that actually true? Ie. that longer focal lengths are inherently easier to design..?

I realise that wide angles are more complex than telephotos, but I was under the impression that the complexity was more related to the desired fov, rather than specific focal length.

Eg. A 40mm for 135 is an optically simple lens, while a 40mm for 120 is far more complex.

 

[lukx]

Is that actually true? Ie. that longer focal lengths are inherently easier to design..?

I realise that wide angles are more complex than telephotos, but I was under the impression that the complexity was more related to the desired fov, rather than specific focal length.

Eg. A 40mm for 135 is an optically simple lens, while a 40mm for 120 is far more complex.

Good point. Similar to what OlivierAOP states. I had mostly lens diagrams for medium to long lenses in mind, which traditionally make do with fewer elements, less prominent curvature of said elements, and are in my experience often better behaved in terms of aberrations. Extreme telephotos may again be a very different story. Maybe the threshold where designs become more complicated varies with respect to the image circle they are supposed to project?

 

[Deleted member 65559]

So with a slow, fine-grained 35mm film and a good lens (medium telephoto) I may achieve results that are very close to a medium format image with the same fov, similar aspect ratio, taken with a medium speed (i.e. grainier) film.

Am I missing anything?

This is really peripheral to the original topic, which really just said the 38mm Biogon was a well-corrected lens. But the image from a 35mm negative will not hold up in larger print sizes. The 'medium/LF look' in my opinion shows mostly in the wider range of fine tonalities in the prints.

 

[zuiko85]

Drum cameras with a curved film path, like the Noblex, would give the least distortion....I think.

 

[oldwino]

Drum cameras with a curved film path, like the Noblex, would give the least distortion....I think.

Or a different kind of distortion.

 

[Deleted member 65559]

That said I get sharper images on digital vs. medium format film.

Though not necessarily better

 

[Godfrey]

...
A term we often read is medium (or large) format "look". I keep wondering what really constitutes this look, if it even exists at all.
...

After fifty some years of photography, what I think of when I say "medium format look" boils down to three things:

- The relationship between DoF and FoV tends to allow better subject isolation since the focal lengths to achieve a given FoV are longer, and the longer focal length lenses at any specific FoV will net less DoF since the physical size of the aperture will be larger for a given f/number setting.

- The increased amount of film area enables more tonality in capture, and lower grain for any specific film type used.

- I find that since the cameras tend to be larger and the number of frames per roll is smaller, the cost per frame is higher, and the photographs made tend to be somewhat more deliberative in nature.

Lots of other things can separate miniature (35mm) from medium format photographs, but given a "standard" camera and normal photography, this is what makes the difference to me. Obtaining that "medium format feel" I get from the Hasselblad SWC on 6x6 film was my Holy Grail for about fifteen years. The Hasselblad 907x fitted with XCD 21mm lens and cropped to square finally achieves it, IMO.

G