Zuiko...D vs. E. vs. F vs. G

Would someone explain the differences between all the different Zuiko lenses found on Olympus rangefinder

cameras. I believe I understand that the letter corresponds to the number of elements in the lens (D is four

while G is 7, right?), but does the larger number of elements mean that it is a higher quality lens and I should

expect better performance? I would assume so, but I read a couple of comments about the Olympus 35LC which has a

G. Zuiko and the people using the camera described their results as not being as sharp as the F. Zuiko on the

35RD. At the same time, the G. Zuiko on the 35-S is described as being "very high quality". I also realize that

just because a lens has more elements doesn't mean it's a better lens, but I wonder how the number of elements in

the Olympus line-up in particular relates to the quality of the lens when they're compared to each other. Does

anyone know or have any thoughts?

Does this help, I'm a rookie at Olympus stuff ... http://zuserver2.star.ucl.ac.uk/~rwesson/esif/om-sif/lensgroup/lensterms.htm ... Jim M.

That's a great read Jim, thanks. I'm a little embarrassed to say that I have been pronouncing my cameras' lens name wrong.

In general, you always need several lens elements to correct a lens for all optical aberrations. Optical aberrations

usually increase with the angle of incident of light rays and the free diameter of a lens element. In other words, wide-

angle lenses and powerful lenses need a higher degree of optical correction - and more lens elements (or, to be

precise, more lens element surfaces). Even the free space between lens elements contributes to the correction,

since the free space forms "a lens element made from air" of which the limiting surfaces also contribute to correction.

 

The bottom line is, the number of lens elements is a rough indicator for the degree of aberration correction achieved.

But it cannot be said in general "more lens elements - better correction", it also depends on the skills of the lens

designer and - not to be forgotten - on the precision of manufacturing. On the Zuiko lenses, the letter stands for the

number of lens elements used: D - 4 elements, F - six elements etc.

 

The Olympus lenses on rangefinder cameras have an excellent reputation, I never heard anything bad about the G-

Zuiko lenses. At least the one on the Olympus 35SP is supposed to be one of the sharpest lenses on rangefinder

cameras.

Jim, thanks for the link. Great site.

 

Winfried--thanks for the info; I believe you answered my questions.

I think glass has been evolving as well as lens design and a four element lens, for example, designed with today's glass may be better than a four element lens of thirty years ago. In other words number of elements is only part of the story. IMHO

The cheap old Pen cameras with simple 4 element Tessar lenses were surprisingly sharp, and the E-Zuiko is widely regarded as an excellently sharp and contrasty lens. In addition to the other's comments, number of elements roughly indicates the type of lens design used, and different types of lens designs are required for different view angles and speeds of lenses. For instance, and f/2.8 normal view angle lens can be very very sharp as a simple 4-element Tessar design, whereas a fast f/1.8 or wide angle lens requires different designs which coincidentally have more elements than a Tessar. In that case you could generalize that an 8 element f/1.8 lens is probably better performance than a 5 element f/1.8 lens, or that an 8 element wide angle lens is probably sharper corner to corner than a 5 element wide angle lens. But comparing an f/1.8 lens to an f/2.8 lens based on the number of lens elements is mostly apples to oranges, especially since you can't actually compare the results of both lenses at all the same apertures since one lens is faster... and slower apertures create more DOF which creates more overall sharpness in the image by default.

Minolta used to do the same thing until around the mid-70's, but would give the number of groups and elements, but the group number was in an odd code. The information is nice to have right on the lens, but it was easy enough to find out if you wanted to know from any maker, since it was always included in the literature on the lenses. Olympus was the only one who stuck to putting it on the lenses (well, the primes anyway) through the '80s. I used to have an OM2n and years later an OM2S, both very nice cameras. I still have a couple of Pens, a Pen EE-S that's still fine, and a Pen D2 which needs some work.

It's true that modern types of optical glass allow for better correction of certain aberrations. Lens designers were very happy when optical glass with extreme values of refraction index and dispersion (which causes chromatic aberrations) appeared. But the biggest step forward in lens design was the introduction of aspherical surfaces which can reduce the number of necessary lens elements drastically. It is not easy to grind aspherical surfaces and lens manufacturers still had some problems manufacturing them in big numbers until some years ago.

 

And another thing - in the early years of lens design designers still had to fight with reflections on lens element surfaces and tried to keep the number of free surfaces as small as possible (a cemented surface has only little reflection), so they tried to reduce the number of lens elements and free surfaces (some Sonnar lenses have three or four elements cemented together). With anti-reflective coating and multicoating, the number of lens element surfaces is no longer a big concern.

FWIW, Nikon did the same in the early days - just with another coding system. Here's the ones that I remember of

the top of my head:

 

T = 3 (Trio)

 

Q = 4 (Quattro)

 

P = 5 (Penta)

 

H = 6 (Hexa)

 

S = 7 (Septem)

 

O = 8 (Octo)

 

N = 9 (Novem)

 

...or something similar... :-)

 

Cheers,

 

Soeren