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

Started Jun 5, 2003 | Discussions thread
OP Mishkin Veteran Member • Posts: 3,654
Re: Yes I think you maybe correct on the AI-Servo --->

Trop, I camped 3 days with my friends and had a great time despite continuous rain. The greens were amazingly intense in the dull overcast light:

It's always cozy to return to this forum after sleeping in the tent filled with water :)))

Troponin wrote:
I decided not to get the 10D, while I wait on the "virtual" 3D.

In any event, great to hear from you again. Did you take some
Vacation or Holiday time-- haven't read many of your posts lately.

Best of luck with your Photog.

Keep in touch.

Trop

Mishkin wrote:
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:

http://www.robgalbraith.com/ubbthreads/showflat.php?Cat=&Board=UBB8&Number=139009&page=0&view=collapsed&sb=5&o=&fpart=1#Post139414

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
already.

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?

-- hide signature --

Mishkin

Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow