"10D has a built-in database for each lens type..."

Started Jun 5, 2003 | Discussions thread
OP Mishkin Veteran Member • Posts: 3,654
Hey Trop

So it looks like we don't have any reports about 50/1.4 being adjusted and having smoother focusing steps.

I think, 50/1.4 is kind of "more compatible" with D60 than it's with 10D. I don't remember 50/1.4 constantly moving in AI Servo mode on D60, but it does on 10D. Anyone with similar feelings? (I can't prove it scientifically, since I no longer have D60).

As for focusing, my 10D seems to have more accurate focus with 50/1.4, D60 had ff or bf problem.

Troponin wrote:
my 50 f/1.4 in with my D60 for a BF problem with my 70-200 f/4L.
The repair ticket stated that they adjust AF on the lens even
though I didn't have a problem with it. In any event, it is still
tack sharp and I don't experience the problem you described.

Honestly, I don't think they did any thing to this lens FWIW.

Mishkin wrote:

"...that allows the camera to modify the commands that are sent to
the lens to initiate focus drive."

  • a quote from Chuck Westfall's post:


Interesting stuff.

1. Are 3rd party lenses in that database? A little scary for
Sigma/Tokina/Tamron, isn't it? We've seen some compatibility issues

2. Yet another proof that lens is not a dumb device responding only
to "focus farther... focus closer... stop!" commands. It's much
more sophisticated than that. Another hint, from 24-70L technical
report: "the autofocus (AF) algorithm is improved, resulting in
even faster AF speed than its predecessor EF28-70mm f/2.8L USM".

( http://www.canon.com/camera-museum/tech/report/200301/report.html ). There's some algorithm programmed in lens' processor. Not just a motor responding to + - signal. Can older lenses be reprogrammed with newer, better "algorithms"?

3. All this returns us to those reports about Canon technicians
saying that some [older] lenses need adjustment for 1.6x crop (or
small pixels, whatever). I wonder if 50/1.4 needs this adjustment.
When I set 10D to AI Servo with 50/1.4, it constantly moves (with a
constant loud noise), with rather large magnitude, which suggests
50/1.4 has too coarse a focusing (at least, per its chip code as it
is) for 10D. Doesn't happen with e.g. 70-200IS. Has anyone noticed
this with 50/1.4? Has anyone improved 50/1.4 by sending it to Canon
with 10D?

In one word: What's going on? How EXACTLY AF works? How body and
lens interact with each other, what do they talk about?

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