a 'normal focal lengthlens is typically defined as havinga focal length equal to the film-format diagonal. in case of 35mm film that is close to 43mm. so, why, I ask don't we see lenses with that focal length?; we have many close to it; 35 or 50mm,but I've never seen 43 or ;let's say 45mm.why do you think that is?I use 35 and 50mm a lot and can see 43 or 45 having an advantagein viewing angle and weight over the typical 500mm normal.confused:
I'm willing to bet it has something to do with that mirror... most 'normal' 50s are retrofocus, to give room for a decent size mirror. The flange to filmplane distance on most slrs is around 45mm.
Quite a lot of 35mm fixed lens rangefinders came with ~45mmlenses, which reminds me that Leica seemed to settle very early on a 50 as their standard - so for that matter did Zeiss with the Contax, although there was no mirror to give room to.
Most probably because Leica was launched with that focal length and people got use to it.
Yet more Leica koolaid...
Plenty of 45mm lenses the Nikon GN Pancake is a 45mm, Pentax made a 43mm lens, Minota MD 45mm, etc.... The lenses for the early Contaflexes were 45mm as well, the standard lens for Contax G was a 45mm Planar. Some fixed lens RF cameras of the 50 to 80's had 45mm lenses. It's interesting to note that many 45mm lenses were Budget lenses and/or Tessar Design. I believe the reason that so few people use these focal lenght has to do with the fact that it's neither wide angle nor tele it's an in-between focal lenght in 35mm. In MF the vast majority of early 6x6 was fitted with what would amount to a 45mm lens the 75mm lens.
I personaly love 45mm lenses because they are just a little wider than 50mm but still offer the advantages of the longer focal length in terms of speed and look.
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Xpan is one 45mm I can think of which can be used in "normal" mode in addition to the panoramic setting. Also, my first 35mm camera was an Olympus Trip which I think was 40mm. Interesting question. Might have been a case of, oh, let's just make it a nice round number?
Normal essentially is what you normally see when you look. Or near when focal length equals the diagonal of the selected image size.
A quick look at my 35mm cameras shows me:
Olympus Trip 40mm
Zeiss Ikon Contina Ic and IIa both 45mm
Agfa Sillette 45mm
Paxette I and II both 45mm
Balda Baldessa 45mm
Minolta Uniomat 45mm
Halina 35X 45mm
Yamato Pal Jr 45mm
That is about half of my 35mm cameras - not rare if 50% of an essentially random selection have 45mm lenses.
I think it needs saying that the diagonal of the image as focal length is a very rule of thumb quantity - there is no biological or mathematical reason for it, it is just a relationship that has been noted to produce a similar flat image as the human eye does on a doubly curved image sensor.
Last edited by Peltigera; 11-30-2013 at 02:32 PM. Click to view previous post history.
Reason: correct grammar.
Rather than express normal in terms of format diagonal, would it not be better to express it as cropped fine definition within peripheral vision? And would that not mean 50mm on a 35mm camera would fit the bill?
Originally Posted by RalphLambrecht
“The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”
As has been said, lots of them out there. Here is only a few I own, or have owned.
Minolta MD 45 (A stunning and very under-rated lens)
45mm Tessar on the Contaflex
Pentax FA43mm Limited
Pentax M 40 (I once toyed with gluing this one to one of my LX's)
Pentax DA 40 Limited (Hands down the best normal lens I have ever owned, and I have owned a lot of them.)
75mm Tessar on Rolleiflex Automat
75mm Solinar on Agfa Super Isolette
Pentax SMC FA and A 75mm for 645 (Another truly stunning and somewhat under rated lens)
I love them every one.