55mm

CMoore · Oct 8, 2015

The 55mm lens.....what is the attraction.?
It seems they are often a Macro/Micro lens, in which case I understand that.
But when it is just a "normal" prime, what makes it a better choice than a 50.?
Is it, simply, another option in your lens arsenal.?
Thank You
http://www.ebay.com/itm/Exc-Canon-F...-From-Japan-/181895809572?hash=item2a59d5ca24

bernard_L · Oct 8, 2015

IMO, it's a better choice for the lens designer. I guess the constrains to design a fast lens with low aberrations, covering a given image circle, are eased when the target focal length is larger, and the field of view, accordingly, smaller. Supporting evidence: the recent Otus prime from Zeiss, 55mm/1.4, that is a Distagon (basically wide-angle) design.

Hopefully a professional optician might chime in and confirm.

MDR · Oct 8, 2015

It's easier for a lens designer to create a faster lens, as for the shooter I like slightly longer normal lenses 5mm doesn't sound like a lot but it does give you a slightly different look. A bit more compression than the 50mm which is already a bit of a longer normal lens normal being 43mm (35mm). Also 50mm are not always 50mm either the Zeiss Contax Sonnar is a 52mm but still sold as a 50mm lens.

cuthbert · Oct 8, 2015

55 and 58mm were popular until the late 70s because easier to calculate for SLR lenses (for RF the designers never had the problem of the mirror so the "right" measurement always been 50mm), as recalled the first 1.4 Planar for the Contarex was a 55mm, nevertheless people demanded 50mm because Barnack stated it was the "correct" standard measure so the maker worked hard to develop 50mm f1.4 first (I think the first design of this kind was the 8 elements Takumar) and later 50mm f1.2 (again a Pentax first in 1975, then Nikon developed its design in 1978, Canon in 1980 and Olympus later)..this is an interesting page regarding the "race for the 50mm f1.2" in the 70s:

http://www.nikkor.com/en/story/0049/

Personally I like the 55mm more because most of the finders of these cameras are smaller than life and the 55mm gives you the "correct" life size (you can notice that when you are holding the camera vertically and shoot with both eyes) that was incidentally what Barnack originally wanted!

jspillane · Oct 8, 2015

I can't profess to know too much about the design characteristics, although MTF of the the recent Sony-Zeiss 55 1.8 and Zeiss Otus 55 1.4 both attest to the fact that it might allow for higher sharpness at wide apertures. I find 55/58's pair well with a 35mm for a two lens kit (I generally prefer 35s to 28s, but 35/50 as a kit doesn't give quite enough differentiation).

Actually, to my mind the perfect kit is 35/58/105, instead of the 'classic' 28/50/85. On 6x6 I prefer 60/100-120 instead of 50/80, as well. If you are shooting with only one lens, I would say that something around 40-50 is ideal, as 55-58's are really creeping out of normal in a way that makes some subjects difficult.

Long story short: If you are shooting a 50 and 55 next to each other they seem nearly the same, but they to slot a little differently into a set of lenses.

CMoore · Oct 8, 2015

Some of this is over my head, but.....very interesting info.
Thanks

MattKing · Oct 8, 2015

CMoore said:
Some of this is over my head, but.....very interesting info.
Thanks

The simplest thing to understand is that it is easier to design the longer lenses because they are naturally farther away from the mirror. A simple, shorter lens might not leave enough space behind it for the mirror.

CMoore · Oct 8, 2015

Ah...I see.....Thank You.

Gerald C Koch · Oct 8, 2015

Before the ready availability of fast computers designing a lens was a slow tedious, manual process taking months or years using ray tracing. Rather than calculate a new lens design it was easier to further optimize an existing one. Hence the proliferation of lenses in the 50mm range. Advantageously this focal length also comes closest to what the human eye perceives as "normal" in field size and perspective. This also applies to other film sizes thus for a 120 format camera a normal lens is 80 mm.

cuthbert · Oct 8, 2015

Gerald C Koch said:
Before the ready availability of fast computers designing a lens was a slow tedious, manual process taking months or years using ray tracing. Rather than calculate a new lens design it was easier to further optimize an existing one. Hence the proliferation of lenses in the 50mm range. Advantageously this focal length also comes closest to what the human eye perceives as "normal" in field size and perspective. This also applies to other film sizes thus for a 120 format camera a normal lens is 80 mm.

Nevertheless all the most important 50mm f1.2 were designed in the mid 70s/early 80s, but it required many decades of refinement from 58mm to 55mm and finally to 50mm, some problems cannot be solved even today, for instance you can design a 50mm Sonnar type lens for SLR.

narsuitus · Oct 11, 2015

cuthbert said:
... some problems cannot be solved even today, for instance you can design a 50mm Sonnar type lens for SLR.

Cuthbert,

Did you mean to say "cannot design" rather than "can design?"

cuthbert · Oct 11, 2015

narsuitus said:
Cuthbert,

Did you mean to say "cannot design" rather than "can design?"

Apologies, yes, you can NOT design a Sonnar 50mm for SLR, I think the shortest Sonnar was a Pentax 58mm, then they switched to a Ultron design for the Takumar lenses.

55mm

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