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Measuring focus speed and precision

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Bodhi Dharma Zen

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Is there a website or a place to read about such tests? I'm interested in getting a new glass for my camera, I'm tired of focus problems and blurry images. Yes, I need sharp pictures and forget about hunting.

Hints?
 
Bodhi Dharma Zen said:
Is there a website or a place to read about such tests? I'm
interested in getting a new glass for my camera, I'm tired of focus
problems and blurry images. Yes, I need sharp pictures and forget
about hunting.

Hints?
Click to expand...
Oh just for clarification, what I mean is if some website runs comparative tests to find out which lens are the fastest to focus with accuracy.
 
As Im sure we all seek for an accurate and fast focus system, I will bump this message so its not lost. Someone most know something. Otherwise, I guess such a site would be extremely helpful for photographers.

Oh well, maybe I would be the only one caring about it.
 
Over at photozone.de > Reviews > Canon EOS Lenses they
have the comparisons for focus speed.
 
Thanks, I will check it.

I have seen that people in this forum is really interested in sharp images, of course you need quality glasses to get them, but IMO the precision and speed of the autofocus system also play a big role. Am I wrong?

I guess I expected more interest in the subject.
 
I don't know of a site with the information you are looking for.

I just wanted to comment that different lenses have different focusing speeds that can be measured. However, the camera body plays a very important role on focus precision. The camera actually "tells" the lens how to reach focus. I suspect that cameras are responsible for many of the focus precision problems people find. It would be very difficult to evaluate the focus precision of lenses without considering the camera body.
 
Thanks for your answer! You expose how ignorant I am, but thats a good thing because I love to learn. So its the relation between the body and the lenses what is in play, interesting, and I can now understand why it is not being tested, as the possible combinations would make it extremely difficult, and possibly expensive, and even tedious.

Anyway, I do believe that such a test would be desirable, so we could choose lenses that were accurate and fast to focus with the body of our preference.
 
Dave Largent said:
Over at photozone.de > Reviews > Canon EOS Lenses they
have the comparisons for focus speed.
Click to expand...
not really, and [a] it is only very approximate, only using 350D,
which might tot be an ideal body for such a purpose

jpr2
 
Bodhi Dharma Zen said:
Is there a website or a place to read about such tests? I'm
interested in getting a new glass for my camera, I'm tired of focus
problems and blurry images. Yes, I need sharp pictures and forget
about hunting.

Hints?
Click to expand...
...I can offer some hints. Begin with a 20D or better. I've heard that the 400D has the same AF as the 20D, so that will qualify. But the 350XT and below does not.

Any lens with ring USM (note: must be ring USM, not just any USM) will have outstanding AF speed and accuracy (although the 85 / 1.2L and 180 / 3.5L macro take a hit for speed). Sigma HSM is also nearly as good, if not equal, in most cases. However, that is not to say that fast and accurate AF is limited to ring USM lenses. Some lenses, such as the Tamron 28-75 / 2.8, while not as fast as ring USM, is still fast and accurate. Other lenses, such as the Sigma 70 / 2.8 macro, which have wicked slow AF, are nonetheless very accurate.

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/
 
joe mama said:
...I can offer some hints. Begin with a 20D or better. I've heard
that the 400D has the same AF as the 20D, so that will qualify. But
the 350XT and below does not.
Click to expand...
yup, but then there are some body specific problems, e.g., 40D (otherwise
an excellent camera) having serious, now pretty well known, central AF point
issue - and in this aspect being easily beaten by it's lesser sister 400D,

to think of it, the OP has a very valid point here = it is strange that no site
dedicates serious effort towards such comparisons :(

jpr2
 
jpr2 said:
yup, but then there are some body specific problems, e.g., 40D
(otherwise
an excellent camera) having serious, now pretty well known, central
AF point
issue - and in this aspect being easily beaten by it's lesser sister
400D,
Click to expand...
What are you talking about? I haven't seen anything but excellent reports of 40D AF accuracy.
 
cyrano said:
cyrano said:
yup, but then there are some body specific problems, e.g., 40D
(otherwise
an excellent camera) having serious, now pretty well known, central
AF point
issue - and in this aspect being easily beaten by it's lesser sister
400D,
Click to expand...
What are you talking about? I haven't seen anything but excellent
reports of 40D AF accuracy.
Click to expand...
take a look at, e.g., here (but there are many similar threads, for my this
problem is a single biggest disappointment with 40D, it is not limited
to when using TCs, as it is pretty hard when 40D and 70-300IS non-DO are
used together):

http://forums.dpreview.com/forums/read.asp?forum=1029&message=25016929

jpr2
 
jpr2 said:
take a look at, e.g., here (but there are many similar threads, for
my this
problem is a single biggest disappointment with 40D, it is not limited
to when using TCs, as it is pretty hard when 40D and 70-300IS non-DO are
used together):

http://forums.dpreview.com/forums/read.asp?forum=1029&message=25016929
Click to expand...
What I got from this thread is simply that the 40D AF won't work outside its published design specifications, which require f/5.6 for AF.

Aside from what you say above (re 70-300IS non-DO,) I haven't seen anything suggesting a systematic problem with 40D AF performance. Can you point to other threads?
 
cyrano said:
Aside from what you say above (re 70-300IS non-DO,) I haven't seen
anything suggesting a systematic problem with 40D AF performance.
Can you point to other threads?
Click to expand...
the Search is off again, and I did not postmarked them in any way, just
have read amongst the spate which appeared in the weeks after 40D
got released at the 20D,30D,40D,50D... forum;

however, it was about 15 mins. after i've actually purchased 40D, that
the described "fault" has reared it's ugly head:
  • relative sensitivity of 40D's central AF point is much less than the remaining
eight (which performance is just stellar imho);
  • just the reverse of the behavior of 400D (which allowed me to go way
beyond the specs, and their f/5.6 limit; either with a single 1.4x, or even
with stacked two 1.4x TC, and mostly also with the non-reporting 2x TC);

thus, I do not care much about the specs. which are useful ref. point but
nothing more - what I've expected was the 40D will be a wast improvement
over 400D in respect to AF capabilities - which it is not,

the question remains WHY something, which was working very well indeed
on 400D was worsened on 40D = a coincidence, or just a crude design
decision driven by their marketing dept., or perhaps it is just another
"accident", like infamous 1D mkIII AF issue ???

and another one - can this be rectified by a firmware upgrade???

FWIW,
jpr2
 
joe mama said:
...I can offer some hints. Begin with a 20D or better. I've heard
that the 400D has the same AF as the 20D, so that will qualify. But
the 350XT and below does not.

Any lens with ring USM
Click to expand...
Thanks Joe, next year I will change my 350D, for now I will focus on glass. I have read good things about the Tamron 17-55, the Canon's 5mm 1.4 & 1.8, the 100 F2, 85 F2, Sigmas 55-200s and a couple more. Ring USM huh? I have never researched that category. Will do it.
 
jpr2 said:
  • relative sensitivity of 40D's central AF point is much less than
the remaining
eight (which performance is just stellar imho);
  • just the reverse of the behavior of 400D (which allowed me to go way
beyond the specs, and their f/5.6 limit; either with a single 1.4x,
or even
with stacked two 1.4x TC, and mostly also with the non-reporting 2x TC);
Click to expand...
The issue you describe is related only to the use of TCs -- and "sensitivity" means its ability to achieve AF at f/5.6 or smaller -- correct?

All my experience with the 40D vs. 20D -- and just about everything I've read, in formal reviews and in these fora -- suggest the AF performance of the 40D (including the center spot) is superior to that of previous xxD bodies. By "performance" I mean its ability to achieve focus under a variety of conditions (including low light and low-contrast subjects) and to do so quickly, repeatably, and accurately.
 
cyrano said:
The issue you describe is related only to the use of TCs -- and
"sensitivity" means its ability to achieve AF at f/5.6 or smaller --
correct?
Click to expand...
almost correct, or it would be, if not for the fact that it
won't AF with the 135/2L + 2x TC + 40D setup,
which means the effective aperture of f/4 - one step
wider than the f/5.6 limit;
strange, and perhaps warranting a further investigation,

best regards,
jpr2
 
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