Sunday, August 31, 2008

Looking For The Perfect Normal

While there are many amazing lenses for the Pentax system, the epitome in the "normal" range is the Pentax smc FA31 Limited. However it retails for around 900 euros. I think it's safe to say that's beyond the budget of many photographers. Is there some lost glass from the past that can replace the FA31, at lower cost? In my search for this elusive prize I've been focusing my attention on Vivitar manual lenses. This, the first article in a series that has developed out of discussions on the Pentax Forum, will set the stage. Future articles will show test shots from various candidate lenses.

First, what does "normal" mean? Back when people bought SLRs that required film, the lens that commonly came with a body was of 50mm focal length. It was considered that this rendered a field of view that looked natural when compared to how we see with our own eyes. The focal length was roughly the same as the diagonal of the 35mm film negative itself.

In 1997 Pentax decided to create the perfect normal lens, so they did the math and realised that 43mm was the exact measurement of the diagonal, not 50mm. Using low tolerance manufacturing techniques, discarding any thoughts of plastic parts, and making cost no object they created the first in their "Limited" range, the Pentax smc FA 43mm Limited. They brought it out in silver metal to match film bodies and even released a Leica version. It caused a bit of a sensation among those who were paying any attention to Pentax.

Now that's all well and good, but what about digital SLRs with the APS-C sensor? The perfect normal for these is 28mm. Happily that was a common focal length even for film cameras, well suited to landscape or candid photos. So there are an awful lot of 28mm lenses floating around on the used market that will work very nicely for anyone desiring a normal field of view on a Pentax DSLR.

Pentax themselves released 28mm lenses, of course, several times through their history. From newest to oldest the lines for the K-mount are the FA, F, A, M and K. Before that Pentax cameras took screw mount lenses in the M42 mount. There are also "universal" mounts released by third-party lens vendors, notably the Tamron Adaptall / Adaptall-2. All of these are usable on current bodies with the correct mount adapter.

Strangely Pentax do not have a 28mm lens in the current line-up. Perhaps that's because the FA31 is so darned good; photographers just buy that instead. But in testing by PopPhoto it came out closer to a 32mm focal length. And 32mm is distinctly different from 28mm. (Pentax are also missing a 24mm.)

Third-party lens manufacturers have not ignored this focal length. There's a very good fast Sigma 28mm, but it's not dead cheap. As I've been more than happy with the Vivitar lenses I own, I thought I would look at that particular firm for buried treasures. The primary advantage over the FA 31 would be cost, but also size, since the Limited lens is surprisingly large (6.85cm long and 345g).

Vivitar never made lenses themselves, but farmed out the manufacturing to various Japanese firms. And my investigations have confirmed that they changed their lenses a bewildering number of times. Later in this series of articles I'll identify every variant I have come across. There are twenty (!) and that is only counting those compatible with Pentax bodies.

In the meantime I will be introducing you to four different 28mm manual-focus Vivitar lenses from the seventies and eighties. I'll provide some nice photos to aid in identification. And I'll take them out for a spin so you can see sample images. I won't be doing formal MTF tests or anything like that, since this is not in my nature. I'm sure you can tell a sharp image when you see it. Raw numbers are useful but don't say it all.

Here are the lenses I'll be sharing. I've given each an ID to aid in reference.

Vivitar Series 1 Auto Wide Angle 28mm f/1.9
Made by Tokina. M42 mount.
This is the fastest lens and the only one to bear the famed "Series 1" label. It is my first M42 lens.

Vivitar Auto Wide-Angle 28mm f/2.8
Made by Tokina. TX mount.
I had never owned a TX mount lens prior to this.

Vivitar Close Focus Wide Angle 28mm f/2.0
Made by Komine. K mount.
The fastest K mount lens in the catalogue. Rather uncommon, perhaps even rare.

Vivitar Wide Angle MC 28mm f/2.8
Made by Komine. K mount.
A commonly-available variant.

As a baseline I'll compare these to a Pentax-A 28mm f/2.8. That's five different 28mm lenses coming your way!

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