1. Price, redesigning the lens to be more economically manufactured with automated machinery.
2. Size, as with the M lenses, the whole thing could be made more compact. BTW, AFAIK no M lens is the same formula as any K lens. The ones that were just continued to be K lenses. The 24/2.8 comes readily to mind, there never was an M version they just continued to sell the K as it was fairly compact to begin with.
3. Optical improvements. As cheap computer ray tracing, and CAM became available it was possible to improve old designs, many very substantially. I don't know how many of you remember how lenses were designed before computers, but basically the drew them up on paper, did a ray trace with protractors, rulers, and pencil. If they aberations were too high they redesigned it and went through the process again. Then again, and again taking maybe a week each time until they got something that was acceptable on paper. Then they made a prototype. If it was bad, they started over. If it was good they went with it as all this was very expensive.
Now with computer ray tracing they design the lens using a specialized CAD program. The computer does a ray trace in minutes, I guess nowadays, and if it is not good they change the glass specifications, or a curve and run it again. As you can see they can now redesign a lens a 100 times in the time it took for them to do it once in the old days. In fact it is fairly easy to design photographic optics these days. In the hand tracing days zooms, for instance, were insanely expensive. Basically the M series were the first that were computer designed. And they were designed using Main Frame computers the only thing with enough power back then. Now you can do it on your Mac or PC.
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Boris Liberman wrote:
Hi!
On the time line first we M42 lenses, then K lenses, then M lenses, then A lenses, then F lenses, then FA lenses. So far so good <g>...
There is something that confuses me. Let us take for example 50/1.7 lens. As far as I understand the optical formula is precisely the same through M, A, F, FA range. I am not certain about K, but probably K is also the same as others. What changed with time was coating and mount (electronics and such).
Now, I'd like to know how many of modern Pentax lenses are original! optical design? It would seem that some lenses are carry over from previous generations.
I have another question. One which is related to M vs K discussion and such.
Some of the K and some of M lenses were very good optically. I mean in terms of resolution, MTF charts, whatever spec minded people have in their mind.
Why would Pentax then want to produce same lens (I mean focal length and aperture) with different optical formula?
Also, I would like to know about computer involvement in lens design. When it started? How it changed the world, so to say?
Now, I realize that if there would be a generous club member willing to enlighten me as much as I am asking, it could be a long story. So feel free to answer off-list...
Of course any link to a web site that has this information would do just as nicely.
Thanks in advance.
Boris
-- graywolf http://graywolfphoto.com
"You might as well accept people as they are, you are not going to be able to change them anyway."
