jsrockit
Moderator
And now Sony has the 40mm 2.5 G lens.
What's the story behind 40mm focal length?
- Thread starter psychoanima
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And now Sony has the 40mm 2.5 G lens.
shawn
Veteran
Armoured
Well-known
That is a bit outside the box!
Panasonic offers a well-regarded 20mm f1.7 - pancake - for micro 4/3; that's an option I'm keeping in mind.
agentlossing
Well-known
The 20/1.7 is THE m4/3 pancake lens, it's one of the oldest and slowest lenses in the system (focus wise) but the results are marvelous. Just keep in mind, 40mm on 4:3 aspect ratio looks a little different than in 3:2.
jsrockit
Moderator
As I move from Fuji APSC to Fuji Medium format, and me mainly liking 40mm now, I was thinking of this... can you tell me more about this?
tbhv55
Well-known
I had the 20mm f/1.7 for m43 until I got out of that system, and it was my favourite lens in m43. As has been stated above by @agentlossing, it is slow to auto-focus, but the results are very pleasing. I also found the 40mm (eq.) focal lens to be very much to my liking.
If you're someone who doesn't require rapid AF performance, then this lens will probably suit you.
N.B. I think I heard that Pansonic released a Mk2 version which (I presume) would have been equipped with improved AF. Maybe someone on here could comment on the Mk2.
agentlossing
Well-known
You know, I've never really studied and come to a conclusion of why I feel differently about 4:3 images compared to 3:2. I believe a 4:3 image has a little less frame on the sides, along with more on the top and bottom, at the same focal length. For most people this is probably hardly important, but I prefer 3:2 and if you crop a 4:3 image to 3:2 you end up losing rather a lot of what was in the frame (and the left and right edges end up a bit tighter than they would be with the same focal length on an actual 3:2 sensor). So a 40mm-equiv on 4:3 somehow seems both wider and tighter at the same time, just based off the way I subconsciously react to it.
3:2 has always seemed more artistic to me - not sure why, although I suppose it is closer to a cinematic angle than 4:3, and most old computer screens, ATM screens, old TVs, etc, are 4:3, which has always seemed like just an awkward format to me. Others swear by it.
Jason Schneider
the Camera Collector
The so-called normal lens for any format is determined by the diagonal of the format because it's equivalent to the minimum diameter of the image circle in which the format can be inscribed. This works out pretty well for formats that are square or not too oblong; less so for formats that are wide and short or tall and narrow. The diagonal of the 24 x 36mm full frame 35mm format is 43.3 mm so that should be the normal lens for that format. The reason 50mm was chosen in the early days of 35mm still photography is that cinema cameras used it as the normal lens for shooting movies on 35mm film in the 18 x 24mm cine format, where it was in effect, a medium telephoto. Why? Because most early movies were essentially stage productions recorded on film and shooting with a 50mm normal lens enabled cinematographers to record the action on stage, cropping out all the extraneous and distracting accoutrements off stage. It is also easier to design lenses that are sharp across the field if they cover a relatively narrow angle. Most early 35mm still cameras used the 18 x 24 mm cine format, but the American made Simplex of 1914 offered at least one model that provided a choice of 18 x 24mm and 24 x 36mm formats, so the landmark Leica I (Model A) of 1925 was not the first 35mm camera to use the latter. Many fixed lens 35mm cameras have had lenses in the 40-45mm range and they are actually closer to being "normal" than 50mm, which is actually a bit on the long side though many people (including me) like it. Sadly I do not own a 40mm f/2 Summicron in M mount, but I do enjoy shooting with my 40mm f/2 G. Zuiko on my Olympus OM-1 and have never considered it an odd or challenging focal length.
shawn
Veteran
Yup, I am the same way. I had the 20mm f1.7 on a GF1 and while it was a very good lens I never felt like I really jelled with it and I think it was from 4:3 format as well. But on the flip side I liked the 14mm and 7.5mm fisheye on the GF1 quite a bit.
Shawn
Armoured
Well-known
As I understand the Mk2 was a slight redesign for better build with some slightly better baffling etc, but no change to the focus performance.
Mind, the Mk2 is already about eight years old, so it's not the newest either.
I would like to try one but don't feel quite compelled enough to pull out the plastic. Yet.
BernardL
Well-known
I read this again and again. Fail to see the causal or logic relation. I can cook up several such "explanations" before breakfast:
- 30mm is the normal focal length because it is the arithmetic mean between the two sides of the frame
- 29mm is the normal focal length because it is the geometric mean between the two sides (hmm, Meyer-Optik Görlitz Orestegon 2.8 29)
40mm is [for me] the normal focal length because that is how my eyes and brain see my surroundings; 'nuf said.
ka7197
Established
If you really believe this then there must be a link missing on the way from your eyes to your brain. Because in fact, our eyes' total field-of-view is similar to a fish-eye lens, and their field-of-view of best vision (such as for reading lines of text) is more like a telephoto lens. The so-called normal lens has nothing to do with the field-of-view or angle-of-view of human vision.
That's strange because the relation is simple enough: When looking at a picture (which is neither tiny nor huge) then we tend to look at it from a distance that is similar to the picture's size. Under this viewing condition, the objects in the picture will have the same angular distances from each other as in real life when the focal length was similar to the camera's film or sensor size, so they will appear 'normal'. As simple as that.
For a 'normal' or natural appearance, telephoto pictures should be looked at from a longer viewing distance, wide-angle pictures from a shorter distance. Of course, that is exactly what we don't do—and that's why pictures taken with a longer-than-normal focal length show the so-called 'telephoto perspective'; those taken with a shorter-than-normal lens appear to have the 'wide-angle perspective'.
Harsh! And rude.
As @BernardL rightly points out with his comment regrding 'causal or logic relation,' there isn't any evidence that any mathematical equation was used to define what's 'normal,' otherwise 50mm wouldn't have been the defacto 'normal' for 135 format since the earliest days.
BernardL
Well-known
I'll survive. This is an internet forum, and one must be prepared for such behavior.
Manners aside, I had written "eye and brain". Including peripheral vision, the eye's FOV is close to 180°: fisheye territory. Then there are various fields of view, with definition increasing as the angle narrows down (attachment). So, the perceived image is a construct of the brain assembled from information provided by the eyes. And the FOV of that perception
(a) is a personal parameter;
(b) does not result from a deficiency of the optical nerve.
Attachments
Armoured
Well-known
I don't have the maths and optics background to defend the particular definition.
But the way I understood the 'normal' definition is that it preserves the spatial perception roughly as we perceive it. Wider and closer objects seem exaggerated, and the distance between objects seems larger than we perceive; longer/tele and those distances seem smaller (compressed).
A side note: an example of this is the now-infamous Biden-Carter picture, where a wide lens arguably made the (closer) Bidens seem exaggeratedly large compared to the (more distant) Carters.
I don't know if that's expressed properly but I also perceive 40mm to be closest to how my brain and eyes see surroundings.
Why 50? I think path dependency just explains a lot of it - plus possibly that very slightly longer is flattering for pictures of people, photographers often want/wanted a bit more 'reach', and it's close enough to 'normal' that any slight spatial perception issues aren't too apparent. Possibly ease of manufacture and early successful/popular optical designs played a role.
But path dependency can play a big role; popular cameras and lenses in 35mm had 50s and that's what others made and copied - in some cases quite literally.
wern0122
Member
On interchangeable lens rangefinders like Leica etc, the most popular two lenses were 50mm and 35mm. If you have only two lenses for a Barnack Leica camera, it's probably 50mm and 35mm. So, when folks built cameras with a fixed lens, they sometimes went with 50 mm, but later on started to compromise by making it a bit wider - 40 mm feels like about half way between 35 and 50 in terms of the user experience. So, it's a compromise.
And, yeah, 40mm focal length on 35mm film can be made with a very simple and tiny lens. My Minolta Minoltina-S has a 40mm f/1.8 lens and it's very small, you'd never guess from a distance that it was a nice camera with a fast lens.
If you want 35mm lens on a RF that fits in a coat pocket, a Barnack Leica or a copy in good condition (Nicca, Zorki-1, etc) with any number of the plentiful and tiny 35mm lenses out there and very nice 35mm bright line viewfinders would be an interesting option, there are just some weird quirks of a Barnack to get used to. EDIT: And, of course, they're HEAVY! 😛 🙂
And, yeah, 40mm focal length on 35mm film can be made with a very simple and tiny lens. My Minolta Minoltina-S has a 40mm f/1.8 lens and it's very small, you'd never guess from a distance that it was a nice camera with a fast lens.
If you want 35mm lens on a RF that fits in a coat pocket, a Barnack Leica or a copy in good condition (Nicca, Zorki-1, etc) with any number of the plentiful and tiny 35mm lenses out there and very nice 35mm bright line viewfinders would be an interesting option, there are just some weird quirks of a Barnack to get used to. EDIT: And, of course, they're HEAVY! 😛 🙂
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