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09-01-2014, 12:43 AM   #1
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Why 55mm in the days of film?

I've been very happy to snatch up the long-normal prime lenses I've come across since I started shooting digital, but the question just occurred to me.

Why was the 55-58mm focal lengths made for film cameras to begin with? It doesn't seem that much different from 50mm and without the crop factor, I have trouble conceiving of an advantage for these focal lengths on film. Does anybody know what advantage they had over their 50mm cousins?

09-01-2014, 01:21 AM   #2
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Not much. Some standard primes were up to were 58mm, and some supposedly 50mm lenses aren't exactly 50mm either. 50mm or 55mm, I find they both work fine for 80% of photos and that 5mm makes no real difference.
09-01-2014, 01:28 AM   #3
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QuoteOriginally posted by jadedrakerider Quote
Does anybody know what advantage they had over their 50mm cousins?
From a users' point of view, I should say that there are none. They all belong to the class of so-called "normal lenses" for 35mm film, meaning that their focal lenghts should be close to the diagonal of 35mm 24 x 36 film (which is 43mm to be more exact) in order to give the beholder a "normal view".

So, why the differences from 43mm to 58mm? Without knowing the details, I guess that this is due to the constraints resulting from the classes of basic lens designs and glass types available to the lens designers. Once you have chosen your design and glass types there will be a limited number of optimum focal lengths.

Photographic lens design - Wikipedia, the free encyclopedia
09-01-2014, 04:17 AM   #4
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Wasnt it the other way around? 58mm and 55mm were out first, but then manufacturers started making them wider, to make them more appealing and faster aperture.
Also, there is a difference in DoF and bokeh. 55mm has more shallow DoF and bigger bokeh balls. 55mm also has a longer working distance and less distortion, which makes it more suited for portraits than a 50mm (which, some photographers claim, is too wide for portraits and has too much distortion and brings the model too close to the photographer) With Pentax you can see this with the DA* 55mm f1.4, which is a portrait lens, while the FA 50mm f1.4 is a general everyday nifty fifty.

But yes, in many cases the differences are practically negligible, and its for you to decide what you need.

09-01-2014, 05:40 AM - 1 Like   #5
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Back in the day, it was about the physics: these days, it's all about the marketing.
09-01-2014, 06:46 AM   #6
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QuoteOriginally posted by Na Horuk Quote
Wasnt it the other way around? 58mm and 55mm were out first, but then manufacturers started making them wider, to make them more appealing and faster aperture.
It was - and I am pretty sure that this was because design- and manufacturing techologies of the day made it easiest to produce 58-55mm lenses with a reasonably fast aperture. But we also did have 50mm f/1.4 takumars (using thorium glass) in those days.

QuoteOriginally posted by dadipentak Quote
Back in the day, it was about the physics: these days, it's all about the marketing.
Yes - but then also: Today we have aspherical lens computation and manufacturing techniques that has in fact made possible, what was only a remote vision back in the day, where all lenses had to be of spherical design. (And by the way: Pentax marketing wasn't too bad back in the day, was it?).
09-01-2014, 07:04 AM   #7
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QuoteOriginally posted by Stone G. Quote
es - but then also: Today we have aspherical lens computation and manufacturing techniques that has in fact made possible, what was only a remote vision back in the day, where all lenses had to be of spherical design. (And by the way: Pentax marketing wasn't too bad back in the day, was it?).
Quite so. And here's the funny thing: I understand marketing a lot better than physics ;~)
09-01-2014, 07:26 AM   #8
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QuoteOriginally posted by Stone G. Quote
And by the way: Pentax marketing wasn't too bad back in the day, was it?
Here is a quote from an old Asahi Pentax catalog about
the SMC Takumar 55 f/1.8 and 55mm f/2
(They shared the same lens elements)

"Razor sharp, fully corrected, high speed standard lenes using rare earth glass,
designed by top lens designers"

I see from Brandt that the Lanthanum group of Schott glass types had high refractive indices in range 1.65 ~1.75
and low dispersion in range 45 ~ 58

Different wording was used for the SMC Takumar 50mm f/1.4 of 7 elements:
"High resolving power combines with outstanding brightness for easier focussing"

09-01-2014, 10:55 AM   #9
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I have read that the Helios 44 were 58mm because they weren't able to get satisfactory edge resolution on a 50mm using old glasses. Early Asahis would have been 55mm for the same reason. After the switch to Thorium there was a big improvement in the 55mm 1.8 edge performance. With rare earth glasses 50mm lenses became practical.
09-01-2014, 12:20 PM   #10
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QuoteOriginally posted by clicksworth Quote
I have read that the Helios 44 were 58mm because they weren't able to get satisfactory edge resolution on a 50mm using old glasses. Early Asahis would have been 55mm for the same reason. After the switch to Thorium there was a big improvement in the 55mm 1.8 edge performance. With rare earth glasses 50mm lenses became practical.
Very interesting! Do you have a link? I am interested in how Asahi created their initial Takumar designs and then developed them into the modern day F and FA series.
09-01-2014, 12:27 PM   #11
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QuoteOriginally posted by 6BQ5 Quote
Very interesting! Do you have a link? I am interested in how Asahi created their initial Takumar designs and then developed them into the modern day F and FA series.
This is a starting point.

Double-Gauss lens - Wikipedia, the free encyclopedia

QuoteQuote:
In 1966, Asahi Pentax combined the Super Speed Panchro type and the Xenon type, invented the 7 glass- 6 grouped Super Takumar 50mm f/1.4(v2).[24] During the 1960s to early 80s every optical house had Super Panchro type, then Super Takumar type Double Gauss normal lenses jockeying for sales. For example, compare the Tokyo Optical RE Auto-Topcor 5.8 cm f/1.4[25] for the Topcon RE Super/Super D (1963), Olympus G. Zuiko Auto-S 40mm f/1.4[26] for the Olympus Pen F (lens 1964, camera 1963), Yashica Auto Yashinon DX 50mm f/1.4[27] for the Yashica TL Super (1967), Canon FL 50mm f/1.4 (v2)[28][29] for the Canon FT (lens 1968, camera 1966), Asahi Optical Super Takumar 50mm f/1.4(v2)[30] for the Pentax Spotmatic (lens 1968, camera 1964), Fuji Fujinon 50mm f/1.4[31] for the Fujica ST701 (1971), Minolta MC Rokkor-PG 50mm f/1.4[32] for the Minolta XK/XM/X-1 (1973), Zeiss Planar HFT 50mm f/1.4[33] for the Rolleiflex SL350 (1974), Konishiroku Hexanon AR 50mm f/1.4[34] for the Konica Autoreflex T3 (lens 1974, camera 1973) and Nippon Kokagu Nikkor (K) 50mm f/1.4 (New)[35] for the Nikon F2 (lens 1976, camera 1971); all from Japan except Zeiss, West Germany.
Early Pentax Takumar Lenses (Careful, may cause uncontrollable LBA).

QuoteQuote:
It is very interesting that after "proving" 3 different design families of standard lenses in the "Pentax year" 1957, one year later only one remains alive - the "Ultron" type made of 6 elements in 5 groups.

When other optical companies erratically changed standard lens design well into the 1970's, Pentax remains stable with this concept.

Even today (2005) this is Pentax standard of this speed and focal length withoout noticeable difference as far as diagrams are examined.

Arguments can be made that it was Pentax who sets this as an industry standard design...

Last edited by boriscleto; 09-01-2014 at 01:01 PM.
09-01-2014, 07:07 PM   #12
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Boris: Read this article from Spotmatic Magazine.on multi-coating and the effect it had on enabling complex lens designs and improving the flare performance of standard designs over time. SMC was a revolutionary addition to optics in 1971.
09-01-2014, 07:51 PM   #13
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QuoteOriginally posted by clicksworth Quote
I have read that the Helios 44 were 58mm because they weren't able to get satisfactory edge resolution on a 50mm using old glasses.
I read that the Helios 44 is 58mm because it was derived from the pre-WWII Zeiss Biotar which was also 58mm. Why the Biotar was 58 mm is anyone's guess, though it was the normal lens for the original Exakta SLR camera. The Biotar is intrinsically sharp in the center at all apertures. That was its design goal. Edge performance is relatively poor however.


Steve

---------- Post added 09-01-14 at 08:00 PM ----------

QuoteOriginally posted by boriscleto Quote
This is a starting point.

Double-Gauss lens - Wikipedia, the free encyclopedia
Excellent, resource!


Steve

Last edited by stevebrot; 09-01-2014 at 07:59 PM.
09-01-2014, 08:01 PM   #14
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QuoteOriginally posted by stevebrot Quote
I read that the Helios 44 is 58mm because it was derived from the pre-WWII Zeiss Biotar which was also 58mm. Why the Biotar was 58 mm is anyone's guess, though it was the normal lens for the original Exakta SLR camera. The Biotar is intrinsically sharp in the center at all apertures. That was its design goal. Edge performance is relatively poor however.


Steve

---------- Post added 09-01-14 at 08:00 PM ----------



Excellent, resource!


Steve
The cine Biotar was 50mm...
09-01-2014, 08:22 PM   #15
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QuoteOriginally posted by stevebrot Quote
Helios 44 is 58mm because it was derived from the pre-WWII Zeiss Biotar which was also 58mm.
Quite so, Helios is a Biotar with the two cemented groups, and has that characteristic sharpness in the center. Apart from the edge resolution another factor could be mirror clearance. There too the higher index glass makes for shallower curvatures and a bit less overall length.
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